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PubMed1982

[Intraluminal angioplasty in the treatment of femoro-popliteal atheromatous lesions. Apropos of 57 cases].

Close cooperation between radiologist and surgeon is essential to prevent major complications of intra-luminal angioplasty, an only mildly aggressive revascularization procedure. Though evolution of an arteritis of the lower limbs can be halted by relief of the stenosis in some cases, the problem remains as to whether this technique is justified at the stage of claudication, even severe. The wider indications for dilatation at the iliac in relation to the femoropopliteal levels in this most recent series reported, testify this tendency.

Aged↗
PubMed2006

Rapid reversion of sequence polymorphisms dominates early human immunodeficiency virus type 1 evolution.

The error-prone replication of human immunodeficiency virus type 1 (HIV-1) enables it to continuously evade host CD8+ T-cell responses. The observed transmission, and potential accumulation, of CD8+ T-cell escape mutations in the population may suggest a gradual adaptation of HIV-1 to immune pressures. Recent reports, however, have highlighted the propensity of some escape mutations to revert upon transmission to a new host in order to restore efficient replication capacity. To more specifically address the role of reversions in early HIV-1 evolution, we examined sequence polymorphisms arising across the HIV-1 genome in seven subjects followed longitudinally 1 year from primary infection. As expected, numerous nonsynonymous mutations were associated with described CD8+ T-cell epitopes, supporting a prominent role for cellular immune responses in driving early HIV-1 evolution. Strikingly, however, a substantial proportion of substitutions (42%) reverted toward the clade B consensus sequence, with nearly one-quarter of them located within defined CD8 epitopes not restricted by the contemporary host's HLA. More importantly, these reversions arose significantly faster than forward mutations, with the most rapidly reverting mutations preferentially arising within structurally conserved residues. These data suggest that many transmitted mutations likely incur a fitness cost that is recovered through retrieval of an optimal, or ancestral, form of the virus. The propensity of mutations to revert may limit the accumulation of immune pressure-driven mutations in the population, thus preserving critical CD8+ T-cell epitopes as vaccine targets, and argue against an unremitting adaptation of HIV-1 to host immune pressures.

CD8-Positive T-Lymphocytes↗
PubMed2005

Variable domains and a VpreB-like molecule are present in a jawless vertebrate.

Immunoglobulins (Igs) and T cell antigen receptors (TCRs) that undergo somatic diversification have not been identified in the two extant orders of jawless vertebrates, which occupy essential positions in terms of understanding the evolution of the emergence of adaptive immunity. Using a single motif-dependent PCR-based approach coupled with a vector that allows selection of cDNAs encoding secretion signal sequences, four different genes encoding Ig V-type domains were identified in the sea lamprey (Petromyzon marinus). One of the predicted proteins encoded by these genes shares structural characteristics with mammalian VpreB molecules, including the absence of a recognizable transmembrane region, a relatively high proportion of charged amino acids in its C-terminal tail and distinctive features of its secretion signal peptide. This is the first indication of a molecule related to the B cell receptor (BCR) complex in a species that diverged prior to the jawed vertebrates in which RAG-mediated adaptive immunity is first encountered.

Amino Acid Sequence↗
PubMed2005

Molecular identification of Sphingomonas sp. A1 alginate lyase (A1-IV') as a member of novel polysaccharide lyase family 15 and implications in alginate lyase evolution.

Sphingomonas sp. A1 (strain A1) produces three endotypes (A1-I [65 kDa], A1-II [25 kDa], and A1-III [40 kDa]) and an exotype (A1-IV [86 kDa]) alginate lyases in cytoplasm. These four enzymes cooperatively depolymerize alginate into constituent monosaccharides. In addition to the genes for these lyases, novel genes encoding hypothetical proteins homologous with A1-IV were found in the genomes of many bacteria including strain A1. One such protein, A1-IV' (90 kDa) of strain A1, was overexpressed in Escherichia coli cells, purified, and characterized. A1-IV' catalyzed the cleavage of glycosidic bonds in alginate through a beta-elimination reaction and released unsaturated di- and trisaccharides as main products, thus indicating that the enzyme is an endotype alginate lyase. A1-IV', which differed from A1-IV in some enzymatic properties, was not expressed in strain A1, suggesting that A1-IV' has no significant role in alginate metabolism. A1-IV' and other A1-IV homologs facilitate the creation of novel polysaccharide lyase family 15 based on their primary structures, implying the evolution route of alginate lyases in family PL-15.

Amino Acid Sequence↗
PubMed1989

[Familial cases of Berger's disease or of Berger's disease and rheumatoid purpura. Cooperative study of the Société Française de Néphrologie].

Several instances of familial Berger's disease have been reported and suggested the possible role of genetic factors in the etiology of the disease. In order to show that familial cases are not a rare finding, a french cooperative study was initiated. It revealed 34 families with 2 or 3 relatives with biopsy-proven Berger's disease. The male predominance (77%) as well as the severity of the evolution (12 out of 69 patients in terminal renal failure) in this series of familial cases are similar to those found in isolated cases. However, the young age at onset (47% being 16 years old or less) deserves to be noted. The number of familial cases is perhaps higher since 90 other families with one patient with Berger's disease and relatives either having urinary abnormalities or terminal renal failure were collected. Although in many of these last patients, clinicians strongly suspected Berger's disease, this diagnosis could not be proven in the absence of immunofluorescent study. This cooperative study has shown that two different glomerular diseases could be encountered in the same family. The association of Henoch-Schönlein purpura and Berger's disease was noted in 4 of these 34 families as well in 11 other and may represent a supplementary argument in favor of a relationship between the two diseases. However, the multiple occurrence of cases in a family may be due to chance or may be the consequence of common environmental factors and does not demonstrate the presence of genetic factors. The use of genetic markers in the families would be helpful to prove the role of these factors in Berger's disease.

Adolescent↗
PubMed1987

Human T-cell leukemia virus type I isolates from Gabon and Ghana: comparative analysis of proviral genomes.

Two isolates of human T-cell leukemia virus type I (HTLV-I) were obtained from lymphocyte cultures of a healthy carrier in Gabon and another in Ghana. Their proviruses were analyzed by Southern blot hybridization and compared with prototypical HTLV-I isolated in Japan and the United States. The provirus genomes of both strains were highly homologous to the prototype HTLV-I along the whole viral genome. The restriction endonuclease sites of the Ghanian isolate were almost identical with those of the prototype HTLV-I, but 10 of 26 sites of the Gabonese isolate were different from those of the prototype. Furthermore, the restriction map of the Gabonese isolate resembled those of a simian T-cell leukemia virus (STLV-I) isolated from a chimpanzee from Sierra Leone and a variant of HTLV-I from Zaire (HTLV-Ib) more closely than those of any other known HTLV-I. These results indicated the existence of some unique strains of HTLV-I transmitted among African people, and the importance of clarifying the origin and transmission of HTLV group viruses.

Biological Evolution↗
PubMed2005

Energy barriers, cooperativity, and hidden intermediates in the folding of small proteins.

Current theoretical views of the folding process of small proteins (< approximately 100 amino acids) postulate that the landscape of potential mean force (PMF) for the formation of the native state has a funnel shape and that the free energy barrier to folding arises from the chain configurational entropy only. However, recent theoretical studies on the formation of hydrophobic clusters with explicit water suggest that a barrier should exist on the PMF of folding, consistent with the fact that protein folding generally involves a large positive activation enthalpy at room temperature. In addition, high-resolution structural studies of the hidden partially unfolded intermediates have revealed the existence of non-native interactions, suggesting that the correction of the non-native interactions during folding should also lead to barriers on PMF. To explore the effect of a PMF barrier on the folding behavior of proteins, we modified Zwanzig's model for protein folding with an uphill landscape of PMF for the formation of transition states. We found that the modified model for short peptide segments can satisfy the thermodynamic and kinetic criteria for an apparently two-state folding. Since the Levinthal paradox can be solved by a stepwise folding of short peptide segments, a landscape of PMF with a locally uphill search for the transition state and cooperative stabilization of folding intermediates/native state is able to explain the available experimental results for small proteins. We speculate that the existence of cooperative hidden folding intermediates in small proteins could be the consequence of the highly specific structures of the native state, which are selected by evolution to perform specific functions and fold in a biologically meaningful time scale.

Biophysics↗
PubMed1997

Mode of disease progression in primary myelodysplastic syndromes: a Japanese co-operative study. The Refractory Anemia Study Group of The Ministry of Health and Welfare, Japan.

Chronological changes in hematological findings were analyzed in 225 patients with myelodysplastic syndromes (MDS). They were diagnosed between 1990 and 1992. Their hematological findings, i.e. hemoglobin levels, leukocyte and platelet counts, proportions of peripheral blood (PB) blasts and monocytes, and proportion of blasts in bone marrow (BM), were recorded for up to 42 months after diagnosis, when available. BM was examined regularly in only a few patients. Therefore, it was impractical to use the French-American-British Cooperative Group criteria for subtype classification during the disease course. Thus, we used the percentage of PB blasts as the only indicator of stage evolution. We classified the disease into four stages: stage 1, less than 1% PB blasts; stage 2, 1-5% PB blasts; stage 3, 5-30% PB blasts; and stage 4, 30% or more PB blasts. There were 171 patients initially in stage 1, 37 initially in stage 2, and 17 initially in stage 3. Less than half (45%) of the patients initially in stage 1 progressed to stage 2, while 91% of the patients initially in stage 2 and all of the patients initially in stage 3 showed stage evolution. Eight variables, i.e. BM blasts 5% or more, male sex, karyotypic abnormalities, micromegakaryocytes, mononuclear large megakaryocytes, platelet counts 50 x 10(9)/l or higher, abnormal nucleus of granulocytes, and abnormal granules of granulocytes, were found to be significant risk factors for evolution from stage 1 to 2. Evolution from stage 1 to a higher stage within 15 months of diagnosis was associated with impending poor prognosis in most patients. However, of the 67 patients initially in stage 1 who died, 30 did not show stage evolution. Evolution from stage 2 to a higher stage and from stage 3 to stage 4 was also associated with impending poor prognosis. Higher levels of cytopenia were not associated with poorer prognosis in the stage 1 patients. In conclusion, our grading system proved to be useful in evaluating the chronological changes in MDS patients.

Disease Progression↗
PubMed2000

Disruptive sexual selection for plumage coloration in a passerine bird.

The theory of sexual selection was developed to explain the evolution of highly exaggerated sexual ornaments. Now supported by vast empirical evidence, sexual selection is generally considered to favour individuals with the most extreme trait expression. Here we describe disruptive selection on a sexual ornament, plumage coloration, in yearling male lazuli buntings (Passerina amoena). In habitats with limited good-quality nesting cover, the dullest and the brightest yearlings were more successful in obtaining high-quality territories, pairing with females and siring offspring, than yearlings with intermediate plumage. This pattern reflects the way that territorial adult males vary levels of aggression to influence the structure of their social neighbourhood. Adult males showed less aggression towards dull yearlings than intermediate and bright ones, permitting the dull yearlings to settle on good territories nearby. Fitness comparisons based on paternity analyses showed that both the adults and dull yearlings benefited genetically from this arrangement, revealing a rare example of sexually selected male-male cooperation.

Animals↗
PubMed2004

Modeling and convergence analysis of distributed coevolutionary algorithms.

A theoretical foundation is presented for modeling and convergence analysis of a class of distributed coevolutionary algorithms applied to optimization problems in which the variables are partitioned among p nodes. An evolutionary algorithm at each of the p nodes performs a local evolutionary search based on its own set of primary variables, and the secondary variable set at each node is clamped during this phase. An infrequent intercommunication between the nodes updates the secondary variables at each node. The local search and intercommunication phases alternate, resulting in a cooperative search by the p nodes. First, we specify a theoretical basis for a class of centralized evolutionary algorithms in terms of construction and evolution of sampling distributions over the feasible space. Next, this foundation is extended to develop a model for a class of distributed coevolutionary algorithms. Convergence and convergence rate analyzes are pursued for basic classes of objective functions. Our theoretical investigation reveals that for certain unimodal and multimodal objectives, we can expect these algorithms to converge at a geometrical rate. The distributed coevolutionary algorithms are of most interest from the perspective of their performance advantage compared to centralized algorithms, when they execute in a network environment with significant local access and internode communication delays. The relative performance of these algorithms is therefore evaluated in a distributed environment with realistic parameters of network behavior.

Journal Article↗
PubMed2004

Lipoprotein cholesteryl ester production, transfer, and output in vivo in humans.

Our aim was to identify and quantify the major in vivo pathways of lipoprotein cholesteryl ester transport in humans. Normal (n = 7), bile fistula (n = 5), and familial hypercholesterolemia (FH; n = 1) subjects were studied. Each received isotopic free cholesterol in HDL, LDL, or particulate form, along with another isotope of free or esterified cholesterol or mevalonic acid. VLDL, intermediate density lipoprotein (IDL), LDL, HDL, blood cells, and bile were collected for up to 6 days for analysis of radioactivity and mass of free and esterified cholesterol. These raw data were subjected to compartmental analysis using the SAAM program. Results in all groups corroborated net transport of free cholesterol to the liver from HDL, shown previously in fistula subjects. New findings revealed that 70% of ester was produced from free cholesterol in HDL and 30% from free cholesterol in LDL, IDL, and VLDL. No evidence was found for tissue-produced ester in plasma. There was net transfer of cholesteryl ester to VLDL and IDL from HDL and considerable exchange between LDL and HDL. Irreversible ester output was from VLDL, IDL, and LDL, but very little was from HDL, suggesting that selective and holoparticle uptakes of HDL ester are minor pathways in humans. It follows that 1) they contribute little to reverse transport, 2) very high HDL would not result from defects thereof, and 3) the clinical benefit of high HDL is likely explained by other mechanisms. Reverse transport in the subjects with bile fistula and FH was facilitated by ester output to the liver from VLDL plus IDL.

Adult↗
PubMed2005

Functional analysis of the chicken delta1-crystallin enhancer activity in Drosophila reveals remarkable evolutionary conservation between chicken and fly.

Functional conservation of enhancers among evolutionarily diverged organisms is a powerful way to identify basic regulatory circuits and key developmental regulators. This is especially applicable to Crystallin genes. Despite unexpected heterogeneity and diversity in their DNA sequences, many studies have revealed that most of the Crystallin genes are regulated by a relatively small set of developmentally important transcription factors. The chicken delta1-crystallin is one of the best-characterized Crystallin genes. Its lens-specific regulation is governed by a 30 bp long DC5 fragment present in the third intron of the gene. DC5 contains PAX6 and SOX2 binding sites, and its activity depends on the cooperative binding of these two transcription factors. To test the idea that Pax6 and Sox2, together with the DC5 enhancer, could form a basic regulatory circuit functional in distantly related animals, we introduced the DC5 fragment into Drosophila and studied its activation pattern and regulation. The results show that the DC5 enhancer is not only active in the compound eye but, remarkably, is specifically active in those cells responsible for Crystallin secretion in Drosophila, i.e. the cone cells. However, regulation of the DC5 enhancer is carried out not by Pax6, but by Pax2 (D-Pax2; shaven--FlyBase) in combination with the Sox2 homologue SoxN. Both proteins (D-PAX2 and SOXN) bind cooperatively to the DC5 fragment and activate the enhancer synergistically. As PAX6 and PAX2 proteins derive from the same ancestor, we propose that during evolution Pax6 function in vertebrate lens development was retained by Pax2 in Drosophila.

Animals↗
PubMed2005

Exploitative and hierarchical antagonism in a cooperative bacterium.

Social organisms that cooperate with some members of their own species, such as close relatives, may fail to cooperate with other genotypes of the same species. Such noncooperation may take the form of outright antagonism or social exploitation. Myxococcus xanthus is a highly social prokaryote that cooperatively develops into spore-bearing, multicellular fruiting bodies in response to starvation. Here we have characterized the nature of social interactions among nine developmentally proficient strains of M. xanthus isolated from spatially distant locations. Strains were competed against one another in all possible pairwise combinations during starvation-induced development. In most pairings, at least one competitor exhibited strong antagonism toward its partner and a majority of mixes showed bidirectional antagonism that decreased total spore production, even to the point of driving whole populations to extinction. Differential response to mixing was the primary determinant of competitive superiority rather than the sporulation efficiencies of unmixed populations. In some competitive pairings, the dominant partner sporulated more efficiently in mixed populations than in clonal isolation. This finding represents a novel form of exploitation in bacteria carried out by socially competent genotypes and is the first documentation of social exploitation among natural bacterial isolates. Patterns of antagonistic superiority among these strains form a highly linear dominance hierarchy. At least some competition pairs construct chimeric, rather than segregated, fruiting bodies. The cooperative prokaryote M. xanthus has diverged into a large number of distinct social types that cooperate with clone-mates but exhibit intense antagonism toward distinct social types of the same species. Most lengthy migration events in nature may thus result in strong antagonism between migratory and resident populations, and this antagonism may have large effects on local population sizes and dynamics. Intense mutual antagonism appears to be more prevalent in this prokaryotic social species than has been observed in the eukaryotic social slime mold Dictyostelium discoideum, which also exhibits multicellular development. The finding of several cases of facultative social exploitation among these natural isolates suggests that such exploitation may occur frequently in nature in many prokaryotes with cooperative traits.

Animals↗
PubMed2003

[Surgical robotics, short state of the art and prospects].

State-of-the-art robotized systems developed for surgery are either remotely controlled manipulators that duplicate gestures made by the surgeon (endoscopic surgery applications), or automated robots that execute trajectories defined relatively to pre-operative medical imaging (neurosurgery and orthopaedic surgery). This generation of systems primarily applies existing robotics technologies (the remote handling systems and the so-called "industrial robots") to current surgical practices. It has contributed to validate the huge potential of surgical robotics, but it suffers from several drawbacks, mainly high costs, excessive dimensions and some lack of user-friendliness. Nevertheless, technological progress let us anticipate the appearance in the near future of miniaturised surgical robots able to assist the gesture of the surgeon and to enhance his perception of the operation at hand. Due to many in-the-body articulated links, these systems will have the capability to perform complex minimally invasive gestures without obstructing the operating theatre. They will also combine the facility of manual piloting with the accuracy and increased safety of computer control, guiding the gestures of the human without offending to his freedom of action. Lastly, they will allow the surgeon to feel the mechanical properties of the tissues he is operating through a genuine "remote palpation" function. Most probably, such technological evolutions will lead the way to redesigned surgical procedures taking place inside new operating rooms featuring a better integration of all equipments and favouring cooperative work from multidisciplinary and sometimes geographically distributed medical staff.

Endoscopy↗