One damage law for different mechanisms

We consider here a general three-dimensional kinetic damage law. It uses the thermodynamic of irreversible processes formalism and the phenomenological aspects of isotropic damage. It gives the damage rate as a function of its associated variable, the strain energy density release rate and the accumulated plastic strain rate. Associated with different plastic constitutive equations, this damage law takes into account brittle damage, ductile damage, low and high cycle fatigue and creep damage. In this paper we mainly focus on creep-fatigue interaction and high cycle fatigue. Associated to a viscoplastic constitutive equation having kinematic hardening, the damage law gives the non linear creep-fatigue interaction. The agreement with experiments is good. Associated to plastic constitutive equations also having kinematic hardening but introduced in a micromechanical two scale model based on the self-consistent scheme, it models the non linear accumulation of damage induced by a succession of sequences of different amplitudes as well as the effect of the mean stress and the influence of non proportional loading.     

IMGT, the International ImMunoGeneTics database

IMGT, the international ImMunoGeneTics database, is an integrated database specialising in Immunoglobulins (Ig), T cell Receptors (TcR) and Major Histocompatibility Complex (MHC) of all vertebrate species, created by Marie-Paule Lefranc, CNRS, Montpellier II University, Montpellier, France (lefranc@ligm.crbm.cnrs-mop.fr). IMGT includes three databases: LIGM-DB (for Ig and TcR), MHC/HLA-DB and PRIMER-DB (the last two in development). IMGT comprises expertly annotated sequences and alignment tables. LIGM-DB contains more than 23 000 Immunoglobulin and T cell Receptor sequences from 78 species. MHC/HLA-DB contains Class I and Class II Human Leucocyte Antigen alignment tables. An IMGT tool, DNAPLOT, developed for Ig, TcR and MHC sequence alignments, is also available. IMGT works in close collaboration with the EMBL database. IMGT goals are to establish a common data access to all immunogenetics data, including nucleotide and protein sequences, oligonucleotide primers, gene maps and other genetic data of Ig, TcR and MHC molecules, and to provide a graphical user friendly data access. IMGT has important implications in medical research (repertoire in autoimmune diseases, AIDS, leukemias, lymphomas), therapeutical approaches (antibody engineering), genome diversity and genome evolution studies. IMGT is freely available at http://imgt.cnusc.fr:8104     

Imaging of angiomyolipomas

In this article we review renal angiomyolipomas (AMLs) from cases in the world literature and 60 cases from our own institution. We also analyze the role and the place of the various imaging techniques in the detection and diagnosis of AMLs. Discussion is focused on the natural history of this benign neoplasm as an isolated form or as a part of the tuberous sclerosis (TS) complex or as part of a third less certain group of multiple AML without stigmata of TS. We also consider the growth patterns and hemorrhagic risks of AML to help define an approach to the current management of this lesion.     

European networks in structural integrity—status in 1995

In this article the objectives and the organisational arrangements of the European Networks AMES (Ageing Materials Evaluation and Studies), ENIQ (European Network for Inspection Qualification) and NESC (Network for Evaluating Steel Components) are described. The Institute for Advanced Materials of the Joint Research Centre in Petten acts as the independent Operating Agent and provides the important Network Management Team to ensure continuity. All the networks are modelled on the successful Programme for the Inspection of Steel Components initiative. The networks AMES, ENIQ and NESC are supported by representatives from diverse organisations such as utilities, owners, fabricators, designers, research establishments, universities and regulatory authorities. They effectively raise the issues of concern and fund the networks whereas the Joint Research Centre at Petten provides the framework for addressing and resolving issues of current interest. The complementary nature of the networks ensures that they receive wide support from bodies such as the European Commission Working Group on Codes and Standards and the various European Commission directorates. Finally it is believed that the rapid advances in networking and information technology via the Internet will lead to more ambitious shared cost projects in the future.     

Effects of Sulfate, Pyrophosphate, and Citrate Ions on the Physicochemical Properties of Cements Made of β-Tricalcium Phosphate-Phosphoric Acid-Water Mixtures

Several additives were selected to increase the setting time of calcium phosphate cements made of β-tricalcium phosphate (β-TCP; β-Ca₃(PO₄)₂)-phosphoric acid-water mixtures. The effects of the additives, i.e., sulfate, pyrophosphate, and citrate ions, are presented in this study. The results show that they all increased the setting time of the cement. Their effectiveness at increasing the setting time is in the order pyrophosphate > citrate > sulfate. The effect of sulfate ions on the setting time is increasingly large below a concentration of 0.1 M . Above that concentration, calcium sulfate dihydrate (CSD; CaSO₄-2H₂O) crystals nucleate and act as nuclei for dicalcium phosphate dihydrate (DCPD; CaHPO₄-2H₂O) crystals, which are the normal product of the setting reaction. This decreases the setting time and decreases the DCPD crystal size, resulting in an increase of the tensile strength of the cement.     

Assessment of trans-fatty acid intake with a food frequency questionnaire and validation with adipose tissue levels of trans-fatty acids

Past studies of the association of trans-fatty acid intake with coronary heart disease have been hindered by the lack of a database on the trans-fatty acid content of various foods. The authors used new data from the US Department of Agriculture to estimate trans-fatty acid intake using a self-administered food frequency questionnaire (FFQ), and they assessed the validity of the FFQ by comparing the dietary estimates with trans-fatty acid concentrations in adipose tissue. The 1996 study included 27 women and 24 men aged 51-78 years. The mean consumption of total trans-fatty acids estimated from the FFQ was 2.24 g per day and 5% of total dietary fat. The mean concentration of total trans-fatty acids in buttock adipose tissue was 4.7% of total fatty acids. Pearson correlations between total dietary intake of trans-fatty acids and total trans-fatty acid levels in adipose tissue were 0.67 (95% confidence interval (CI) 0.36-0.84) among men and 0.58 (95% CI 0.26-0.79) among women. After adjustment for energy intake, age, and body mass index, the correlation coefficients were 0.76 (95% CI 0.51-0.89) among men and 0.52 (95% CI 0.17-0.75) among women. The FFQ validated in this study is an important new tool for assessing usual intake of trans-fatty acids.     

Involvement of lipid peroxidation in platelet signalling

A well-known signalling pathway in blood platelets consists in the release of arachidonic acid (AA) from membrane phospholipids and its specific oxygenation into bioactive derivatives. In particular, cyclic prostaglandin endoperoxides and thromboxane A2 are potent inducers of platelet functions and are produced in greater amounts when the level of lipid hydroperoxides is higher than normal, as 'physiological concentrations' of such peroxides activate the cyclooxygenation of AA. In this context, a lower activity of platelet glutathione peroxidase (GPx), the key-enzyme for the degradation of lipid hydroperoxides, has been reported in aging, which will ensure a longer life span to those peroxides. Accordingly, the biosynthesis of pro-aggregatory prostanoids is elevated in platelets from the elderly. On the other hand, fatty acids from marine origin have been recognized as inhibitors of platelet functions, and they may alter the redox status of cells. They may for instance increase the platelet GPx activity, an effect that can be prevented by antioxidants. Overall, these data point out the relevance of the redox status in platelet functions.     

Mycobacterium avium complex common-source or cross-infection in AIDS patients attending the same day-care facility

To delineate the epidemiology of Mycobacterium avium complex (MAC) infection in acquired immunodeficiency syndrome patients, we studied 32 case patients with disseminated MAC infection who attended the same daycare facility during a period of 13 months. Pulsed-field gel electrophoresis analysis showed very low similarity between MAC strains, suggesting that, despite close contacts between the patients, nosocomial cross-transmission or exposure to a common source of MAC did not occur.     

Bone repair of defects filled with a phosphocalcic hydraulic cement: an in vivo study

A quickly setting calcium phosphate-based hydraulic cement mixed with particles of tricalcium phosphate (TCP) ceramic was implanted in 56 metaphysial defects made in the long bones of ten adult mongrel dogs. Microradiography, histology and scanning electron microscopy (SEM) demonstrated the slow resorption of the cement and the bony incorporation of the calcium phosphate ceramic particles which were consistently embedded in bone. The original structural pattern of the bone tended to be restored 7 months after implantation. The cement did not hinder the incorporation of the calcium phosphate ceramic particles, neither did it elicit any inflammatory or foreign-body response. The cement was easily shaped and allowed a perfect filling of any defect, resulting in close contact of the whole implant surface with the host bone at the time of surgery, associated with appreciable mechanical strength. Most of the practical problems associated with the use of calcium phosphate ceramics in the repair of bone defects could be overcome with the cement.