SEARCH · PubMed Health

Results for “Comparative evolution”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

PubMed2006

Trends in antimicrobial resistance phenotypes in non-typhoid Salmonellae from human and poultry origins in France.

A total of 1873 strains from human origin and 4283 strains from non-human origin of Salmonella enterica serotypes Typhimurium, Enteritidis, Heidelberg, Hadar and Virchow, collected over three years 1993, 1997 and 2000, were examined in order to determine the rate of antimicrobial resistance to 12 antimicrobial drugs. The objective of the study was to describe and to compare the evolution of the main resistance types in human and non-human isolates, focusing on the poultry sector. The evolution and the rates of antimicrobial resistances for the five serotypes, with the exception of Virchow, were almost comparable in strains isolated from human and non-human sources over the period studied. The most striking result concerning single resistance was the spectacular increase of the resistance frequency to nalidixic acid for the strains belonging to serotypes Hadar and Virchow, especially in the poultry food sector (14% in 1993 vs. 72% in 2000 for Salmonella Virchow, 4% in 1993 vs. 70% in 2000 for Salmonella Hadar) and also in human isolates (24% in 1997 vs. 48% in 2000 for S. Virchow, 31% in 1997 vs. 78% in 2000 for S. Hadar). In addition to the classical resistance to ampicillin, streptomycin, sulphonamide, chloramphenicol and tetracycline (ASSuCT resistance type), which stabilized between 1997 and 2000, the emergence of a new resistance type was observed.

Animals↗

PubMed1998

Different evolution of simian immunodeficiency virus in a natural host and a new host.

To address the mechanisms of host-virus adaptation and pathogenesis of lentiviral infections, we compared the evolution of the same isolate of simian immunodeficiency virus (SIVsmm9) in two different situations: nonpathogenic infection of its natural host, the sooty mangabey, and AIDS-inducing infection of a new host, the rhesus macaque. Samples were obtained at 6, 12, and 23 or 30 months postinfection from three animals of each species. Sequences were derived from the V1 and V2 domains of the surface glycoprotein. In the macaques, we observed specific variations absent from all mangabey samples, indicating that different host species select different virus variants. In the macaques, we also observed a different shape in the phylogenetic tree, a lower divergence of sibling sequences, and a lower synonymous/nonsynonymous change ratio than in the mangabeys. This suggests that the viral population is larger and submitted to weaker selection pressures when host-virus adaptation is achieved, such as in the mangabey.

Adaptation, Physiological↗

PubMed2000

[Vogt-Koyanagi-Harada syndrome: importance of rapid diagnosis and therapeutic intervention].

AIM: The Vogt-Koyanagi-Harada (VKH) syndrome is characterized by a bilateral granulomatous uveitis with exudative retinal detachments associated with systemic manifestations such as meningeal signs, cutaneous signs (poliosis, alopecia and vitiligo) and dysacousis. VKH is relatively unfrequent in Europe and Switzerland. Therefore diagnosis is often reached with some delay. Our aim here was to analyze the 3 patients for whom the diagnosis was reached less than 15 days after the first signs and compare their evolution to seven patients for whom diagnosis was known one month or more after the first signs. PATIENTS AND METHODS: Retrospective and partially prospective study of patients seen at uveitis clinic in Lausanne from 1990 to 1999 for whom an ICG angiographic work-up had been performed in addition to the usual clinical and fluoresceinic work-up. The frequency of VKH in our collective was calculated; symptoms and signs, paraclinical investigations, laboratory work-up, delay from first signs to diagnosis, the management and the evolution were the criteria analyzed. In particular the patients with early diagnosis and early treatment were analyzed and compared to the rest of the collective. Diagnosis was based on the criteria of the American Uveitis Society. Between 1990 and 1999, 14 patients with the diagnosis of VKH were seen (1.2% of our collective of uveitis patients). The 10 patients having had a work-up including ICG angiography in addition to the classical work-up were included in this study. RESULTS: The diagnosis was reached in less than 2 weeks in 3 patients. In all 3 patients inflammation was controlled after treatment. Two patients with a follow-up without recurrence of respectively 36 and 54 months were considered as healed. The last case had no recurrence after nine months but still was under therapy. Whereas clinical examination and fluorescein angiography failed to show any sequels in the 2 "healed" patients, ICG angiography showed numerous zones of hypofluorescence indicating choroidal scarring. For the 7 other cases, the diagnosis was reached one month or more after the first symptoms or signs and they all evolved in the chronic recurrent fashion. ICG angiography contributed to the rapid diagnosis in 2/3 patients with early diagnosis and was an essential parameter for the choroidal follow-up in 9/10 patients. CONCLUSION: This study shows that it is essential to rapidly reach the diagnosis of VKH and treat the patients vigorously without delay. By showing choroidal lesions not seen by the clinical examination or fluorescein angiography. ICG angiography is essential for a correct work-up and follow-up of choroidal lesions in VKH. In our two "healed" patients it was the only mean to show choroidal sequellae.

Adult↗

PubMed2006

Differential evolution of thyroid peroxidase and thyrotropin receptor antibodies in Graves' disease: thyroid peroxidase antibody activity reverts to pretreatment level after carbimazole withdrawal.

In this study, we compared the evolution of thyroid peroxidase antibody (TPOAb) and thyroid-stimulating antibody (TSAb) activities before, during, and after treatment of Graves' disease (GD) with carbimazole. TPOAb and TSAb were measured in sera from 75 patients with GD, during an 18-month block-replace regimen and after drug withdrawal (12, 24, and 36 months). At diagnosis, TPOAb were present in 85% of the patients versus 99% for TSAb. During the treatment, TPOAb values and prevalence significantly decreased, as observed with TSAb. After drug withdrawal, TPOAb levels increased once again to reach the pretreatment values, whereas TSAb remained unchanged. TPOAb values and prevalence at drug withdrawal were not significantly different between patients who remained euthyroid and those who had a relapse of hyperthyroidism. In contrast, TSAb values and prevalence were higher at drug withdrawal in relapse patients. In conclusion, TPOAb and TSAb changes are similar during GD treatment by carbimazole but diverge after drug withdrawal. TPOAb might reflect autoimmune perturbations independently of the clinical status and of the thyroid-stimulating activity.

Adult↗

PubMed2006

Evolutive standard base excess and serum lactate level in severe sepsis and septic shock patients resuscitated with early goal-directed therapy: still outcome markers?

PURPOSE: To compare the evolution of standard base excess and serum lactate level between surviving and non surviving patients with severe sepsis and septic shock resuscitated with early goal-directed therapy. METHODS: This is a retrospective study in an intensive care unit of a university tertiary hospital where 65 consecutive severe sepsis and septic shock patients were observed without any intervention in the treatment by the authors of this report. RESULTS: In our study, the mortality of severe sepsis and septic shock patients was 38%. The central venous oxygen saturation of both groups was above 70% after the resuscitative period, excluding the second day of the non survivors group (69.8%). After the second day, the central venous oxygen saturation was significantly higher in the survivors group (P < .001). Standard base excess was initially low in both groups, but from the second day on, the correction of standard base excess was significantly more successful and linear in the survivor group (P < .001). Lactate levels were similar during the evolution of both groups. CONCLUSIONS: Although evolutive standard base excess and serum lactate level are still outcome markers in severe sepsis and septic shock patients resuscitated with early goal-directed therapy, other studies must be performed to clarify if hemodynamic interventions based on standard base excess and serum lactate level could be reliable to improve clinical outcomes in severe sepsis and septic shock patients.

APACHE↗

PubMed2003

Significantly different patterns of amino acid replacement after gene duplication as compared to after speciation.

We have performed a large-scale analysis of amino acid sequence evolution after gene duplication by comparing evolution after gene duplication with evolution after speciation in over 1,800 phylogenetic trees constructed from manually curated alignments of protein domains downloaded from the PFAM database. The site-specific rate of evolution is significantly altered by gene duplication. A significant increase in the proportion of amino acid substitutions at constrained (slowly evolving) sites after duplication was observed. An increase in the proportion of replacements at normally constrained amino acid sites could result from relaxation of purifying selective pressure. However, the proportion of amino acid replacements involving radical changes in amino acid properties after duplication does not appear to be significantly increased by relaxed selective pressure. The increased proportion of replacements at constrained sites was observed over a relatively large range of protein change (up to 25% amino acid replacements per site). These findings have implications for our understanding of the nature of evolution after duplication and may help to shed light on the evolution of novel protein functions through gene duplication.

Algorithms↗

PubMed2000

Evolution of leukotriene B4, peptide leukotrienes, and interleukin-8 plasma concentrations in patients at risk of acute respiratory distress syndrome and with acute respiratory distress syndrome: mortality prognostic study.

OBJECTIVE: To compare the evolution of plasma concentrations of leukotriene (LT) B4, LTC4, LTD4, and interleukin (IL)-8 in patients with acute respiratory distress syndrome (ARDS) and in patients at risk of ARDS and to assess the value of these mediators in predicting mortality rate from ARDS. DESIGN: A case-control study comparing ARDS patients and patients at risk of ARDS as well as survivors and nonsurvivors with ARDS. SETTING: Hospital intensive care unit, laboratory, and department of hematology. PATIENTS: Twenty-one patients with ARDS and 14 patients at risk of ARDS. INTERVENTION: Arterial blood samples were collected on days 0, 1, and 5 after admission to the intensive care unit. MEASUREMENTS AND MAIN RESULTS: LTs were extracted, separated by high-pressure liquid chromatography and quantified by enzyme immunoassay. IL-8 was analyzed by ELISA. Plasma concentrations of LTB4 and LTC4 plus LTD4 were significantly higher in ARDS patients than in patients at risk of ARDS during the first 24 hrs. Concentrations of IL-8 were also higher in ARDS patients than in patients at risk throughout the study, although the differences between the two groups were only significant on day 5. Only the plasma concentration of LTB4 on day 1 was a marker of ARDS (72.2% sensitivity, 84.6% specificity). A logistic regression analysis showed that LTB4 and IL-8, on day 1, were markers of mortality rate in patients with ARDS (70.0% sensitivity, 87.5% specificity). CONCLUSIONS: LTs are elevated during the early phases of ARDS, whereas IL-8 increases throughout the study. The evaluation of LTB4 and IL-8 may be useful prognostic indices in patients with early phase ARDS after admission to the intensive care unit.

Biomarkers↗

PubMed1998

Gridded genomic libraries of different chordate species: a reference library system for basic and comparative genetic studies of chordate genomes.

The use of genomic libraries maintained in arrayed format is becoming a more and more popular tool for the analysis of molecular evolution and comparative molecular development. Being able to use already existing reference libraries considerably reduces the work load, and if results are made publicly available, it will facilitate in silica experiments in the future. Here we describe the construction and preliminary characterization of six cosmid libraries of different chordate species, Ciona intestinalis (Hemichordate), Branchiostoma floridae (Cephalochordate), Lampetra fluviatilis (Cyclostoma), Xiphophorus maculatus, and Danio rerio (Osteichthyes) in Lawrist7 and Fugu rubripes in Lawrist4.

Animals↗

PubMed1998

Interspecies comparative genome hybridization and interspecies representational difference analysis reveal gross DNA differences between humans and great apes.

Comparative chromosome G-/R-banding, comparative gene mapping and chromosome painting techniques have demonstrated that only few chromosomal rearrangements occurred during great ape and human evolution. Interspecies comparative genome hybridization (CGH), used here in this study, between human, gorilla and pygmy chimpanzee revealed species-specific regions in all three species. In contrast to the human, a far more complex distribution of species-specific blocks was detected with CGH in gorilla and pygmy chimpanzee. Most of these blocks coincide with already described heterochromatic regions on gorilla and chimpanzee chromosomes. Representational difference analysis (RDA) was used to subtract the complex genome of gorilla against human in order to enrich gorilla-specific DNA sequences. Gorilla-specific clones isolated with this technique revealed a 32-bp repeat unit. These clones were mapped by fluorescence in situ hybridization (FISH) to the telomeric regions of gorilla chromosomes that had been shown by interspecies CGH to contain species-specific sequences.

Animals↗

PubMed2002

[At what care level are cyclo-oxygenase-2 inhibitors prescribed?].

OBJECTIVES: To find the evolution in the billing of prescriptions for selective cyclooxygenase-2 (COX-2) inhibitors since they came on the market and to compare this evolution in primary care (PC) and specialist care (SC).Design. Cross-sectional, descriptive study. SETTING: Toledo Health Area. Main measurements. Data were obtained from the System of Drug Information (SIFAR) to analyse the monthly turnover of NSAID prescriptions (M01A group in the official classification of medicines, including rofecoxib and celecoxib) issued by doctors in PC and SC between January 2000 and June 2001. RESULTS: In our area during the study period, 583,558 NSAID packages were prescribed; 6.61% were COX-2 inhibitors, which represented 29.08% of NSAID expenditure. 98.23% of NSAID packages and 94.61% of COX-2 inhibitors were prescribed in PC. The use of COX-2 inhibitors in SC rose from 10.03% of the total NSAIDs in February 2000 to 29.79% in June 2001; whilst in PC it rose from 1.52% to 10.78%. Rofecoxib and celecoxib were third and fifth in the lists of most prescribed NSAIDs (number of packages) in SC, and ninth and twelfth in PC. In terms of cost of prescription, they were first and second in SC, and first and fourth in PC. CONCLUSIONS: COX-2 inhibitors have become the main NSAIDs prescribed. The appearance of these drugs had a different impact on SC and PC doctors, with greater use of them and a more rapid introduction in SC.

Cross-Sectional Studies↗

PubMed1997

[Current treatment of candidemia in non-neutropenic patients. Amphotericin B or fluconazole? A retrospective study of 62 consecutive patients].

BACKGROUND: To analyze the epidemiologic characteristics of non-neutropenic patients with candidemia in a general hospital and the advantages and disadvantages of treatment with amphotericin B or fluconazole. PATIENTS AND METHODS: A total of 62 adult non-neutropenic patients with candidemia and treated with amphotericin B (n = 35) or fluconazole (n = 27) were studied. All episodes were considered to be associated with infection in a vein catheter. The demographic characteristics, risk factors for the development of candidemia, Candida species recovered from blood culture, underlying diseases, and clinical manifestations in both groups were compared. The evolution regarding secondary effects developed with both drugs, therapy failures, long term complications, and overall mortality rate associated with candidemia were analyzed. RESULTS: Both groups were comparable with the exception of the percentage of patients infected with species different from Candida albicans, which was higher in the group of patients who received amphotericin B (57%) than in the fluconazole group (26%) (p = 0.02), and in that patients with severe renal failure or AIDS had received preferentially fluconazole. There were no statistically significant differences regarding the evolution of patients treated with amphotericin B or fluconazole with the following factors: therapy failure (27% versus 19%; p = 0.7), overall mortality rate (40% versus 44%; p = 0.6), and mortality directly related to candidemia (33% versus 30%). Mortality was significantly higher among patients who had not their vein catheters removed early (78%) compared with those who had their vein catheters removed early (34%) (p = 0.01). Sixty-six percent of patients treated with amphotericin developed some severe secondary effect, whereas no patient in the fluconazole group developed such effects. CONCLUSIONS: Both amphotericin B and fluconazole seem to be effective drugs for the treatment of vein catheter related candidemia in the non-neutropenic patient, although fluconazole is far less toxic. The early removal of the vein catheter plays a prognostic role with at least the same relevance than the type of antifungal therapy chosen.

Adult↗

PubMed2004

Comparative study of adaptive molecular evolution in different human immunodeficiency virus groups and subtypes.

Molecular adaptation, as characterized by the detection of positive selection, was quantified in a number of genes from different human immunodeficiency virus type 1 (HIV-1) group M subtypes, group O, and an HIV-2 subtype using the codon-based maximum-likelihood method of Yang and coworkers (Z. H. Yang, R. Nielsen, N. Goldman, and A. M. K. Pedersen, Genetics 155:431-449, 2000). The env gene was investigated further since it exhibited the strongest signal for positive selection compared to those of the other two major HIV genes (gag and pol). In order to investigate the pattern of adaptive evolution across env, the location and strength of positive selection in different HIV-1 sequence alignments was compared. The number of sites having a significant probability of being positively selected varied among these different alignment data sets, ranging from 25 in HIV-1 group M subtype A to 40 in HIV-1 group O. Strikingly, there was a significant tendency for positively selected sites to be located at the same position in different HIV-1 alignments, ranging from 10 to 16 shared sites for the group M intersubtype comparisons and from 6 to 8 for the group O to M comparisons, suggesting that all HIV-1 variants are subject to similar selective forces. As the host immune response is believed to be the dominant driving force of adaptive evolution in HIV, this result would suggest that the same sites are contributing to viral persistence in diverse HIV infections. Thus, the positions of the positively selected sites were investigated in reference to the inferred locations of different epitope types (antibody, T helper, and cytotoxic T lymphocytes) and the positions of N and O glycosylation sites. We found a significant tendency for positively selected sites to fall outside T-helper epitopes and for positively selected sites to be strongly associated with N glycosylation sites.

Adaptation, Physiological↗

PubMed2006

Comparative genomic analysis links karyotypic evolution with genomic evolution in the Indian muntjac (Muntiacus muntjak vaginalis).

The karyotype of Indian muntjacs (Muntiacus muntjak vaginalis) has been greatly shaped by chromosomal fusion, which leads to its lowest diploid number among the extant known mammals. We present, here, comparative results based on draft sequences of 37 bacterial artificial clones (BAC) clones selected by chromosome painting for this special muntjac species. Sequence comparison on these BAC clones uncovered sequence syntenic relationships between the muntjac genome and those of other mammals. We found that the muntjac genome has peculiar features with respect to intron size and evolutionary rates of genes. Inspection of more than 80 pairs of orthologous introns from 15 genes reveals a significant reduction in intron size in the Indian muntjac compared to that of human, mouse, and dog. Evolutionary analysis using 19 genes indicates that the muntjac genes have evolved rapidly compared to other mammals. In addition, we identified and characterized sequence composition of the first BAC clone containing a chromosomal fusion site. Our results shed new light on the genome architecture of the Indian muntjac and suggest that chromosomal rearrangements have been accompanied by other salient genomic changes.

Animals↗

PubMed1999

Comparative genomics of the Archaea (Euryarchaeota): evolution of conserved protein families, the stable core, and the variable shell.

Comparative analysis of the protein sequences encoded in the four euryarchaeal species whose genomes have been sequenced completely (Methanococcus jannaschii, Methanobacterium thermoautotrophicum, Archaeoglobus fulgidus, and Pyrococcus horikoshii) revealed 1326 orthologous sets, of which 543 are represented in all four species. The proteins that belong to these conserved euryarchaeal families comprise 31%-35% of the gene complement and may be considered the evolutionarily stable core of the archaeal genomes. The core gene set includes the great majority of genes coding for proteins involved in genome replication and expression, but only a relatively small subset of metabolic functions. For many gene families that are conserved in all euryarchaea, previously undetected orthologs in bacteria and eukaryotes were identified. A number of euryarchaeal synapomorphies (unique shared characters) were identified; these are protein families that possess sequence signatures or domain architectures that are conserved in all euryarchaea but are not found in bacteria or eukaryotes. In addition, euryarchaea-specific expansions of several protein and domain families were detected. In terms of their apparent phylogenetic affinities, the archaeal protein families split into bacterial and eukaryotic families. The majority of the proteins that have only eukaryotic orthologs or show the greatest similarity to their eukaryotic counterparts belong to the core set. The families of euryarchaeal genes that are conserved in only two or three species constitute a relatively mobile component of the genomes whose evolution should have involved multiple events of lineage-specific gene loss and horizontal gene transfer. Frequently these proteins have detectable orthologs only in bacteria or show the greatest similarity to the bacterial homologs, which might suggest a significant role of horizontal gene transfer from bacteria in the evolution of the euryarchaeota.

Amino Acid Sequence↗

PubMed2005

Comparative developmental genetics and the evolution of arthropod body plans.

The arthropods display a wide range of morphological diversity, varying tagmosis, as well as other aspects of the body plan, such as appendage and cuticular morphology. Here we review the roles of developmental regulatory genes in the evolution of arthropod morphology, with an emphasis on what is known from morphologically diverse species. Examination of tagmatic evolution reveals that these changes have been accompanied by changes in the expression patterns of Hox genes. In contrast, review of the modifications to wing morphology seen in insects shows that these body plan changes have generally favored alterations in downstream target genes. These and other examples are used to discuss the evolutionary implications of comparative developmental genetic data.

Animals↗

PubMed1985

Photosynthetic Development of Anaerobically Grown Rice (Oryza sativa) after Exposure to Air.

During anaerobic germination, rice produces a coleoptile devoid of carotenoid and chlorophyll. Further development and greening of the shoot occur upon exposure of the seedlings to air. In this study, a comparison was made between anaerobically (N(2)) germinated rice, greened upon exposure to air, and air/dark (A/D) germinated seedlings, greened upon exposure to light. After exposure to air, N(2)-grown seedlings had a 76-hour lag before net oxygen evolution occurred compared to a 6-hour lag for A/D-grown seedlings. After 98 h of greening, N(2)-grown seedlings reached a rate of oxygen evolution equivalent to that of A/D-grown seedlings after 24 hours. Chlorophyll and carotenoid content showed a similar lag, but did not reach the level found in A/D-grown seedlings even after 124 hours of exposure to air. RuBPcase activity also lagged in N(2)-grown seedlings, ultimately reaching greater values than in the ;greened' A/D-grown seedlings. Phosphoenolpyruvate carboxylase activity was constant and low in all treatments except for a transient increase after 24 hours of greening of the N(2)-grown seedlings.

Journal Article↗

PubMed2006

Early time evolution of Freédericksz patterns generated from states of electroconvection.

We report on the early time ordering in a nematic liquid crystal subjected to a sudden change in an external ac electric field. We compare time evolution for two different initial states of electroconvection. Electroconvection is a highly driven state of a nematic liquid crystal involving convective motion of the fluid and periodic variations of the molecular alignment. By suddenly changing either the voltage or the frequency of the applied ac field, the system is brought to the same thermodynamic conditions. The time ordering of the system is characterized by the evolution of features of the power spectrum, including the average wave number, total power, and shape of the power spectrum. We observe that ordering of the system occurs faster after a sudden change in frequency than it does after a sudden change in voltage.

Journal Article↗

PubMed2005

Telomere maintenance, function and evolution: the yeast paradigm.

Telomeres are multifunctional genetic elements that cap chromosome ends, playing essential roles in genome stability, chromosome higher-order organization and proliferation control. The telomere field has largely benefited from the study of unicellular eukaryotic organisms such as yeasts. Easy cultivation in laboratory conditions and powerful genetics have placed mainly Saccharomyces cerevisiae, Kluveromyces lactis and Schizosaccharomyces pombe as crucial model organisms for telomere biology research. Studies in these species have made it possible to elucidate the basic mechanisms of telomere maintenance, function and evolution. Moreover, comparative genomic analyses show that telomeres have evolved rapidly among yeast species and functional plasticity emerges as one of the driving forces of this evolution. This provides a precious opportunity to further our understanding of telomere biology.

Ascomycota↗