Showing papers by "Université catholique de Louvain published in 1995"
TL;DR: By combining the rationale of pro- and prebiotics, the concept of synbiotics is proposed to characterize some colonic foods with interesting nutritional properties that make these compounds candidates for classification as health-enhancing functional food ingredients.
Abstract: Because the human gut microbiota can play a major role in host health, there is currently some interest in the manipulation of the composition of the gut flora towards a potentially more remedial community. Attempts have been made to increase bacterial groups such as Bifidobacterium and Lactobacillus that are perceived as exerting health-promoting properties. Probiotics, defined as microbial food supplements that beneficially affect the host by improving its intestinal microbial balance, have been used to change the composition of colonic microbiota. However, such changes may be transient, and the implantation of exogenous bacteria therefore becomes limited. In contrast, prebiotics are nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species already resident in the colon, and thus attempt to improve host health. Intake of prebiotics can significantly modulate the colonic microbiota by increasing the number of specific bacteria and thus changing the composition of the microbiota. Nondigestible oligosaccharides in general, and fructooligosaccharides in particular, are prebiotics. They have been shown to stimulate the growth of endogenous bifidobacteria, which, after a short feeding period, become predominant in human feces. Moreover, these prebiotics modulate lipid metabolism, most likely via fermentation products. By combining the rationale of pro- and prebiotics, the concept of synbiotics is proposed to characterize some colonic foods with interesting nutritional properties that make these compounds candidates for classification as health-enhancing functional food ingredients.
7,232 citations
TL;DR: In this article, the authors performed a comprehensive analysis of relations between baseline clinical data and 30-day mortality and developed a multivariable statistical model for risk assessment in candidates for thrombolytic therapy.
Abstract: Background Despite remarkable advances in the treatment of acute myocardial infarction, substantial early patient mortality remains. Appropriate choices among alternative therapies and the use of clinical resources depend on an estimate of the patient's risk. Individual patients reflect a combination of clinical features that influence prognosis, and these factors must be appropriately weighted to produce an accurate assessment of risk. Prior studies to define prognosis either were performed before widespread use of thrombolysis or were limited in sample size or spectrum of data. Using the large population of the GUSTO-I trial, we performed a comprehensive analysis of relations between baseline clinical data and 30-day mortality and developed a multivariable statistical model for risk assessment in candidates for thrombolytic therapy. Methods and Results For the 41 021 patients enrolled in GUSTO-I, a randomized trial of four thrombolytic strategies, relations between clinical descriptors routinely collected at initial presentation, and death within 30 days (which occurred in 7% of the population) were examined with both univariable and multivariable analyses. Variables studied included demographics, history and risk factors, presenting characteristics, and treatment assignment. Risk modeling was performed with logistic multiple regression and validated with bootstrapping techniques. Multivariable analysis identified age as the most significant factor influencing 30-day mortality, with rates of 1.1% in the youngest decile ( 75 (adjusted chi(2)=717, P<.0001). Other factors most significantly associated with increased mortality were lower systolic blood pressure (chi(2)=550, P<.0001), higher Killip class (chi(2)=350, P<.0001), elevated heart rate (chi(2)=275, P<.0001), and anterior infarction (chi(2)=143, P<.0001). Together, these five characteristics contained 90% of the prognostic information in the baseline clinical data. Other significant though less important factors included previous myocardial infarction, height, time to treatment, diabetes, weight, smoking status, type of thrombolytic, previous bypass surgery, hypertension, and prior cerebrovascular disease. Combining prognostic variables through logistic regression, we produced a validated model that stratified patient risk and accurately estimated the likelihood of death. Conclusions The clinical determinants of mortality in patients treated with thrombolytic therapy within 6 hours of symptom onset are multifactorial and the relations complex. Although a few variables contain most of the prognostic information, many others contribute additional independent prognostic information. Through consideration of multiple characteristics, including age, medical history, physiological significance of the infarction, and medical treatment, the prognosis of an individual patient can be accurately estimated.
1,093 citations
TL;DR: In this article, the authors proposed a data-driven bandwidth selection procedure, which can be used to select both constant and variable bandwidths, based on a residual squares criterion along with a good approximation of the bias and variance of the estimator.
Abstract: When estimating a mean regression function and its derivatives, locally weighted least squares regression has proven to be a very attractive technique. The present paper focuses on the important issue of how to select the smoothing parameter or bandwidth. In the case of estimating curves with a complicated structure, a variable bandwidth is desirable. Furthermore, the bandwidth should be indicated by the data themselves. Recent developments in nonparametric smoothing techniques inspired us to propose such a data-driven bandwidth selection procedure, which can be used to select both constant and variable bandwidths. The idea is based on a residual squares criterion along with a good approximation of the bias and variance of the estimator. The procedure can be applied to select bandwidths not only for estimating the regression curve but also for estimating its derivatives. The resulting estimation procedure has the necessary flexibility for capturing complicated shapes of curves. This is illustrated via a large variety of testing examples, including examples with a large spatial variability. The results are also compared with wavelet thresholding techniques, and it seems that our results are at least comparable, i.e. local polynomial regression using our data-driven variable bandwidth has spatial adaptation properties that are similar to wavelets.
577 citations
TL;DR: There was an ontogenic evolution of salt resistance and the young seedling stage appeared to be the most sensitive to NaCl during vegetative growth, but short- and middle term effects of stress have to be distinguished for each genotype since some varieties showed better growth during the second week of stress than during the first, whilst others showed an opposite trend.
Abstract: The effects of NaCl stress on growth and development of rice (Oryza sativa L.) were studied and compared in varieties of various origins. During the vegetative stage, tall indica landraces (Nona Bokra, Buhra Rata, Panwell, and Pokkali) appeared to be resistant throughout while in japonica varieties (I Kong Pao (IKP) and Tainung 67) and elite breeding lines (IR 4630, in 2153 and in IR 31785), resistance fluctuated. Panwell, which was the only indica variety evaluated during the reproductive stage, also expressed salt resistance during booting, heading and grain maturation while varieties with the greatest variability in salt stress response during the vegetative phase (IR 4630, in 31785 and IKP) also showed the greatest variability during reproductive development. Thus, varietal levels of resistance to salinity at different growth stages are not necessarily interdependent characteristics. Variability in salt resistance of different genotypes during the vegetative and reproductive phases of development was not correlated to their mean level of relative resistance. There was an ontogenic evolution of salt resistance and the young seedling stage appeared to be the most sensitive to NaCl during vegetative growth. Nevertheless, short- and middle term effects of stress have to be distinguished for each genotype since some varieties showed better growth during the second week of stress than during the first, whilst others showed an opposite trend. Moreover, even at specific stages of development, plant responses to NaCl were quite variable according to the criterion used to quantify salinity resistance. The identification of genotypes resistant to NaCl at specific developmental stages is essential to improve the understanding of the effects of salt stress upon phenology and to elaborate further breeding programmes.
565 citations
TL;DR: In this paper, the role of time in nonparametric efficiency analysis is examined using both FDH and DEA technologies, and it is shown how each observation in a panel can be characterized in efficiency terms vis-a-vis three different kinds of frontiers: (i) "contemporaneous", (ii) "sequential", and (iii) "intertemporal".
516 citations
TL;DR: The treatment of adiabatic perturbations within density-functional theory is examined, at arbitrary order of the perturbation expansion, and the general expressions are specialized for the second, third, and fourth derivative of the energy.
Abstract: The treatment of adiabatic perturbations within density-functional theory is examined, at arbitrary order of the perturbation expansion. Due to the extremal property of the energy functional, standard variation-perturbation theorems can be used. The different methods (Sternheimer equation, extremal principle, Green's function, and sum over state) for obtaining the perturbation expansion of the wave functions are presented. The invariance of the Hilbert space of occupied wave functions with respect to a unitary transformation leads to the definition of a ''parallel-transport-gauge'' and a ''diagonal-gauge'' perturbation expansion. Then, the general expressions are specialized for the second, third, and fourth derivative of the energy, with an example of application of the method up to third order.
512 citations
01 Jun 1995
TL;DR: The description of a conditional access system is given and it is shown that equitable systems need the use of a trusted third party.
Abstract: Digital TV broadcasting needs new cryptological tools for conditional access, copyright protection and image authentication. The aim of this paper is to overview the corresponding systems' features. The description of a conditional access system is given. It is shown that equitable systems need the use of a trusted third party. The design of efficient copyright protection by watermarking images and image authentication by signatures are also briefly discussed. >
486 citations
TL;DR: By functional complementation of a PDR5 null mutant of Saccharomyces cervisiae, the multidrug-resistance gene CDR1 of Candida albicans is cloned and sequenced, revealing that it encodes a putative membrane pump belonging to the ABC (ATP-binding cassette) superfamily.
Abstract: By functional complementation of a PDR5 null mutant of Saccharomyces cerevisiae, we have cloned and sequenced the multidrug-resistance gene CDR1 of Candida albicans. Transformation by CDR1 of a PDR5-disrupted host hypersensitive to cycloheximide and chloramphenicol resulted in resistance to cycloheximide, chloramphenicol and other drugs, such as the antifungal miconazole, with collateral hypersensitivity to oligomycin, nystatin and 2,4 dinitrophenol. Our results also demonstrate the presence of several PDR5 complementing genes in C. albicans, displaying multidrug-resistance patterns different from PDR5 and CDR1. The nucleotide sequence of CDR1 revealed that, like PDR5, it encodes a putative membrane pump belonging to the ABC (ATP-binding cassette) superfamily. CDR1 encodes a 1501-residue protein of 169.9 kDa whose predicted structural organization is characterized by two homologous halves, each comprising a hydrophobic region with a set of six transmembrane stretches, preceded by a hydrophilic nucleotide binding fold.
459 citations
433 citations
TL;DR: It appears that the muscle-tendon work of locomotion is most accurately measured when energy transfers are only included between segments of the same limb, but not among the limbs or between the limbs and the centre of mass of the whole body.
Abstract: The muscle-tendon work performed during locomotion can, in principle, be measured from the mechanical energy of the centre of mass of the whole body and the kinetic energy due to the movements of the body segments relative to the centre of mass of the body. Problems arise when calculating the muscle-tendon work from increases in mechanical energy, largely in correctly attributing these increases either to energy transfer or to muscle-tendon work. In this study, the kinetic and gravitational potential energy of the centre of mass of the whole human body was measured (using a force platform) simultaneously with calculation of the kinetic and potential energy of the body segments due to their movements relative to the body centre of mass (using cinematography) at different speeds of walking and running. Upper and lower boundaries to the total work were determined by including or excluding possible energy transfers between the segments of each limb, between the limbs and between the centre of mass of the body and the limbs. It appears that the muscle-tendon work of locomotion is most accurately measured when energy transfers are only included between segments of the same limb, but not among the limbs or between the limbs and the centre of mass of the whole body.
377 citations
TL;DR: The problem of tracking with stability of a reference trajectory is solved by means of linearizing "static" and "dynamic" state feedback laws by giving conditions to avoid possible singularities of the feedback laws.
Abstract: We are concerned in this article with the control of wheeled mobile robots, which constitute a class of nonholonomic mechanical systems. More precisely, we are interested in solving the problem of tracking with stability of a reference trajectory, by means of linearizing ''static'' and ''dynamic'' state feedback laws. We give conditions to avoid possible singularities of the feedback laws.
TL;DR: In this paper, the authors proposed a cooperative game-theoretic approach for sharing national abatement costs through international financial transfers, inspired by a classical solution concept from the theory of cooperative games.
Abstract: For a simple economic model of transfrontier pollution, widely used in theoretical studies of international treaties bearing on joint abatement, we offer in this paper a scheme for sharing national abatement costs through international financial transfers that is inspired by a classical solution concept from the theory of cooperative games—namely, the core of a game. The scheme has the following properties: total damage and abatement costs in all countries are minimized (optimality property), and no coalition or subset of countries can achieve lower total costs for its members by taking another course of action in terms of emissions or transfers, under some reasonable assumption about the reactions of those not in the coalition (core property). In the concluding section economic interpretations of the scheme are proposed, including its connection with the free riding problem.
TL;DR: The proton-pump ATPase of the plant plasma membrane acts as a primary transporter by pumping protons out of the cell, thereby creating pH and electrical potential differences across the plasmalemma and promoting more specialized physiological functions.
Abstract: The proton-pump ATPase (H+-ATPase) of the plant plasma membrane acts as a primary transporter by pumping protons out of the cell, thereby creating pH and electrical potential differences across the plasmalemma (Fig. 1). Transport of many solutes (ions, metabolites, etc.) into and out of the cell involves secondary transporters whose ability to function is directly dependent on the proton-motive force created by the H+-ATPase. Depending on the electrical charge of the solute to be transported, the direction of its transport, and its concentration on either side of the membrane, it is possible to predict from Figure 1 the type of transport protein required. For instance, the uptake of a cation is energetically favorable because of the positive external electrical potential, and therefore requires only a diffusion facilitator, such as a channel protein or a uniport. Conversely, to be energetically favorable, the uptake of an anion must be accompanied by the uptake of one or more protons in a symport system. In addition to activating secondary transport, the H+-ATPase promotes more specialized physiological functions.
TL;DR: The location of the "spacer-receptor" unit in a 4-aminonaphthalimide fluorophore, which undergoes internal charge transfer in the excited state, is crucial for the suitability of the compound as a pH sensor as discussed by the authors.
Abstract: The location of the “spacer–receptor” unit in a 4-aminonaphthalimide fluorophore, which undergoes internal charge transfer in the excited state, is crucial for the suitability of the compound as a pH sensor. In studies of the pH dependence of the fluorescence of the regioisomers 1 and 2, only 1 displayed desirable properties.
TL;DR: In this paper, the authors used a model reacting mixture containing compounds representative of the molecules that must react to permit a primary stabilisation of the pyrolytic oil: 4-methylacetophenone (4-MA), diethylsebacate (DES), and guaiacol (GUA).
TL;DR: A general demonstration of the existence of variational principles for an even order of perturbation, when constraints are present, is provided here.
Abstract: When perturbation theory is applied to a quantity for which a variational principle holds (eigenenergies of Hamiltonians, Hartree-Fock or density-functional-theory energy, etc.), different variational perturbation theorems can be derived. A general demonstration of the existence of variational principles for an even order of perturbation, when constraints are present, is provided here. Explicit formulas for these variational principles for even orders of perturbation, as well as for the ''2n + 1 theorem,'' to any order of perturbation, with or without constraints, are also exhibited. This approach is applied to the case of eigenenergies of quantum-mechanical Hamiltonians, studied previously by other methods.
TL;DR: The objective of the paper is to assess the strengths and weaknesses of one of these methodologies on a nontrivial benchmark; and to illustrate and discuss a number of challenging issues that need to be addressed for such methodologies to become effective in supporting real, complex requirements engineering tasks.
Abstract: Recently a number of requirements engineering languages and methods have flourished that not only address 'what' questions but also 'why', 'who' and 'when' questions. The objective of the paper is twofold: to assess the strengths and weaknesses of one of these methodologies on a nontrivial benchmark; and to illustrate and discuss a number of challenging issues that need to be addressed for such methodologies to become effective in supporting real, complex requirements engineering tasks. The problem considered here is that of a distributed meeting scheduler system; the methodology considered is the KAOS goal directed language and method. The issues raised from this case study include goal identification, the "deidelization" of unachievable goals, the handling of interfering goals, the impact of early formal reasoning, the merits of early reuse of abstract descriptions and categories, requirements traceability and the need to link requirements to retractable assumptions, and the potential benefits of hybrid acquisition strategies.
Ludwig Institute for Cancer Research1, University Hospital of Lausanne2, Université catholique de Louvain3, Cliniques Universitaires Saint-Luc4, University of Bari5, University of Liège6, Université libre de Bruxelles7, Curie Institute8, Goethe University Frankfurt9, European Organisation for Research and Treatment of Cancer10
TL;DR: MAGE expression in primary tumors was correlated with tumor thickness: there was a significantly increased frequency in the expression of MAGE‐1, ‐2 and ‐3 in tumors of greater thickness.
Abstract: Human genes MAGE-1 and MAGE-3 code for antigens that are recognized on melanoma cells by autologous cytolytic T lymphocytes. These antigens may constitute useful targets for specific anti-tumor immunization of cancer patients, since genes MAGE-1 and MAGE-3 are expressed in a number of tumors of different histological types, but are not expressed in normal adult tissues other than testis. This also applies to genes MAGE-2 and MAGE-4, which are closely related to MAGE-1 and MAGE-3. We have analyzed the expression of these 4 MAGE genes in cutaneous melanoma. Sixteen of 100 primary tumors vs. 69 (48%) of 145 metastases from individual patients expressed MAGE-1. Similar differences in the frequency of gene expression between primary and metastatic tumor samples were observed for MAGE-2, MAGE-3, and MAGE-4. MAGE expression in primary tumors was correlated with tumor thickness: there was a significantly increased frequency in the expression of MAGE-1, -2 and -3 in tumors of greater thickness. Benign and dysplastic nevi, as well as in site melanomas, did not express any of the 4 MAGE genes. (C) 1995 Wiley-Liss, Inc.
TL;DR: The results suggest that, like other soluble dietary fibers, OFS significantly alters liver lipid metabolism, resulting over time in a significant reduction in plasma triglyceride, phospholipid and cholesterol levels.
Abstract: The present study was aimed at answering the question why feeding rats an oligofructose (OFS) supplemented diet could cause a significant reduction in plasma lipid levels. Daily administration of a 10% (w/w) OFS-containing diet to normolipidemic male rats resulted in a decrease in plasma triglycerides, phospholipids and cholesterol. The triglyceride-lowering effect was observed after one week and lasted for at least 16 wk and was associated with a reduction in plasma very low density lipoproteins, indicating that the hypolipidemic effect of OFS may be due to changes in liver lipid metabolism. We therefore tested whether OFS feeding modified the capacity of the liver to synthesize triglycerides from free fatty acids. Hepatocytes isolated from livers of control and OFS-fed rats were incubated in the presence of [1-14C]palmitate, and both intracellular and extracellular [14C]triglyceride formation were quantified. We found that chronic feeding of an OFS-supplemented diet to rats significantly reduced the capacity of isolated hepatocytes to synthesize triglycerides from palmitate. The results suggest that, like other soluble dietary fibers, OFS significantly alters liver lipid metabolism, resulting over time in a significant reduction in plasma triglyceride, phospholipid and cholesterol levels.
TL;DR: In this article, the molecular characterization of maleic anhydride melt-functionalized polypropylene (PP-g-MA) was discussed, the functionalization mechanism, the nature, the concentration, and the location of grafted anhydrides species onto the poly-propylene chain are discussed.
Abstract: This work deals with the molecular characterization of maleic anhydride melt-functionalized polypropylene (PP-g-MA). The functionalization mechanism, the nature, the concentration, and the location of grafted anhydride species onto the polypropylene chain are discussed. The polypropylene functionalization was performed using a pre-heated Brabender Plastograph (190 degrees C, 4 min of mixing time). Several concentrations of maleic anhydride and organic peroxide were used for this study. In those experimental conditions, the organic peroxide undergoes an homolytic rupture and carries out a polypropylene tertiary hydrogen abstraction. The resulting macroradical undergoes a beta-scission leading to a radical chain end which reacts with maleic anhydride. When a termination reaction occurs at this first step a succinic type anhydride chain end is obtained. However, oligomerization of maleic anhydride is found to occur more frequently leading to poly( maleic anhydride) chain end. Concentration of both anhydride types and minimal length of the grafted poly(maleic anhydride) were determined. A fraction of maleic anhydride does not react with polypropylene or homopolymerize leading to nongrafted poly(maleic anhydride). (C) 1995 John Wiley and Sons, Inc.
TL;DR: In this article, the atomic temperature factors of the two allotropic forms of the SiO-O 2 and stishovite were calculated as a function of temperature from ab initio phonon band structures.
Abstract: The constant-volume specific heat, the entropy, the phonon contributions to internal energy and Helmholtz free energy, and the atomic temperature factors of \ensuremath{\alpha}-quartz and stishovite, two allotropic forms of ${\mathrm{SiO}}_{2}$, are calculated as a function of temperature from ab initio phonon band structures. Available experimental data agree with our calculated values over a wide range of temperature. \ensuremath{\alpha}-quartz has more accessible phonon states at low temperatures, while stishovite has larger contributions to the thermodynamic functions from the zero-point motion.
TL;DR: A network of genes involved in multiple drug resistance of the yeastS.
Abstract: This minireview describes a network of genes involved in multiple drug resistance of the yeast S. cerevisiae. The transcription regulators, PDR1, PDR3, PDR7, and PDR9 control the expression of the gene PDR5, encoding a membrane protein of the ATP-binding-cassette superfamily and functioning as a drug extrusion pump. Next to PDR5, several other target genes, encoding membrane pumps of the ABC type, such as SNQ2, STE6, PDR10, PDR11, YOR1, but also other membrane-associated (such as GAS1, D4405) or soluble proteins (such as G3PD), involved or not in multidrug resistance, are found to be controlled by PDR1. On another side, the PDR3 regulator participates with its homolog PDR1 to co- and auto-regulation circuits of yeast multidrug resistance.
TL;DR: It is shown that the time profile of the harmonics emitted by a single atom exposed to a strong electromagnetic field may be obtained through a wavelet or a Gabor analysis of the acceleration of the atomic dipole, shedding some light on the competition between the atomic excitation or ionization processes and photon emission.
Abstract: We show that the time profile of the harmonics emitted by a single atom exposed to a strong electromagnetic field may be obtained through a wavelet or a Gabor analysis of the acceleration of the atomic dipole. This analysis is extremely sensitive to the details of the dynamics and sheds some light on the competition between the atomic excitation or ionization processes and photon emission. For illustration we study the interaction of atomic hydrogen with an intense laser pulse.
TL;DR: A new multiple access communications system based on the combination of multitone transmission and direct sequence spectrum spreading (DS/SS) is proposed because the associated larger symbol duration is favorable to combat the effects of multipath propagation.
Abstract: The paper proposes a new multiple access communications system based on the combination of multitone transmission and direct sequence spectrum spreading (DS/SS). Multitone transmission is proposed because the associated larger symbol duration is favorable to combat the effects of multipath propagation. The multiple access capability of the system is achieved by means of DS/SS which also helps to combat the presence of several paths. On the other hand, DS/SS is also attractive to decrease the multiple access interference. The performance of this system is investigated for a multipath, slowly Rician fading and frequency selective channel, and a suboptimal receiver based on matched filters. The multiple access interference is also taken into account, A model for the computation of the bit error probability is derived for QPSK modulation of the orthogonal tones by the spread symbols. The system performance is investigated for selection diversity and maximal ratio combining (RAKE reception). Then the influence of the number of tones is investigated for given bandwidth, bit rate and transmission power. The positive effect of a multitone spread spectrum transmission is demonstrated. >
TL;DR: Feeding fermentable fructo-oligosaccharides may constitute a good way to counteract syndromes resulting from hyperammonemia or disturbed Fe, Ca, Mg and Zn homeostasis.
01 Jan 1995
TL;DR: “Projection Pursuit” (PP) stands for a class of exploratory projection techniques that contains methods designed for analyzing high dimensional data using low-dimensional projections.
Abstract: “Projection Pursuit” (PP) stands for a class of exploratory projection techniques. This class contains methods designed for analyzing high dimensional data using low-dimensional projections. The main idea is to describe “interesting” projections by maximizing an objective function or projection pursuit index.
TL;DR: The results suggest that in patient LB33 the melanoma cells may have lost the expression of several HLA molecules under the selective pressure of an anti‐tumor CTL response.
Abstract: We have studied the patterns of antigens recognized by autologous cytolytic T lymphocytes (CTL) on two melanoma cell lines derived from metastases that were removed from patient LB33 at several years distance. Cell line LB33-MEL.A was obtained after surgery in 1988. A large number of CTL clones directed against LB33-MEL.A was obtained with blood lymphocytes collected from the patient in 1990. In vitro selection of melanoma cells that were resistant to these CTL clones indicated that al least five different antigens were recognized on LB33-MEL.A by autologous CTL. Four of these antigens were found to be presented by HLA-A28, B13, B44 and Cw6, respectively. The patient remained disease-free until 1993 when a metastasis was detected and was used to obtain cell line LB33-MEL.B. This cell line proved resistant to lysis by all the CTL clones directed against the LB33-MEL.A cells and showed no expression of HLA class I molecules except for HLA-A24. Using LB33-MEL.B cells to stimulate blood lymphocytes collected from the patient in 1994 we derived CTL clones that lysed these cells. All these CTL clones recognized a new antigen presented by HLA-A24. These results suggest that in patient LB33 the melanoma cells may have lost the expression of several HLA molecules under the selective pressure of an anti-tumor CTL response.
TL;DR: In this paper, the recurrence coefficients of semi-classical orthogonal polynomials related to a weight function w such that w/w is a rational function were shown to be solutions of nonlinear differential equations with respect to a well-chosen parameter.
TL;DR: In this article, the existence of nontrivial critical points of functionals with a local Linking at 0 was proved for both elliptic boundary value problems and Hamiltonian systems.
TL;DR: It is proposed that this new role of MMPs is a major component of the mechanism that determines where and when the osteoclasts will attack the bone.
Abstract: A key event in bone resorption is the recruitment of osteoclasts to future resorption sites, We follow here the migration of preosteoclasts from the periosteum to the developing marrow cavity of fetal mouse metatarsals in culture, and investigate the role of proteinases and demineralization in this migration, Our approach consisted in testing inhibitors of proteinases and demineralization on the migration kinetics, Migration was monitored by histomorphometry and the (pre)osteoclasts were identified by their tartrate resistant acid phosphatase (TRAP) activity, At the time of explantation, TRAP+ cells (all mononucleated) are detected only in the periosteum, and the core of the diaphysis (future marrow cavity) consists of calcified cartilage, Upon culture, TRAP+ cells (differentiating progressively into multinucleated osteoclasts) migrate through a seam of osteoid and a very thin and discontinuous layer of mineral, invade the calcified cartilage and transform it into a 'marrow' cavity; despite the passage of maturing osteoclasts, the osteoid develops into a bone collar, The migration of TRAP+ cells is completely prevented by matrix metalloproteinase (MMP) inhibitors, but not by a cysteine proteinase inhibitor, an inhibitor of carbonic anhydrase, or a bisphosphonate, The latter three drugs inhibit, however, the resorptive activity of mature osteoclasts at least as efficiently as do the MMP inhibitors, as assessed in cultures of calvariae and radii, Furthermore, in situ hybridizations reveal the expression of 2 MMPs, gelatinase B (MMP-9 or 92 kDa type IV collagenase) in (pre)osteoclasts, and interstitial collagenase (MMP-13) in hypertrophic chondrocytes, Tt is concluded that only MMPs appear obligatory for the migration of (pre)osteoclasts, and that this role is distinct from the one MMPs may play in the subosteoclastic resorption compartment, We propose that this new role of MMPs is a major component of the mechanism that determines where and when the osteoclasts will attack the bone.