PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Biological 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 271 records · Page 15Linked to original sources
PubMed1999

Evolution and biological characterization of human immunodeficiency virus type 1 subtype E gp120 V3 sequences following horizontal and vertical virus transmission in a single family.

It has been suggested that immune-pressure-mediated positive selection operates to maintain the antigenic polymorphism on the third variable (V3) loop of the gp120 of human immunodeficiency virus type 1 (HIV-1). Here we present evidence, on the basis of sequencing 147 independently cloned env C2/V3 segments from a single family (father, mother, and their child), that the intensity of positive selection is related to the V3 lineage. Phylogenetic analysis and amino acid comparison of env C2/V3 and gag p17/24 regions indicated that a single HIV-1 subtype E source had infected the family. The analyses of unique env C2/V3 clones revealed that two V3 lineage groups had evolved in the parents. Group 1 was maintained with low variation in all three family members regardless of the clinical state or the length of infection, whereas group 2 was only present in symptomatic individuals and was more positively charged and diverse than group 1. Only virus isolates carrying the group 2 V3 sequences infected and induced syncytia in MT2 cells, a transformed CD4(+)-T-cell line. A statistically significant excess of nonsynonymous substitutions versus synonymous substitutions was demonstrated only for the group 2 V3 region. The data suggest that HIV-1 variants, possessing the more homogeneous group 1 V3 element and exhibiting the non-syncytium-inducing phenotype, persist in infected individuals independent of clinical status and appear to be more resistant to positive selection pressure.

Amino Acid Sequence↗
PubMed1983

Experimental hepatic iron overload in the baboon: results of a two-year study. Evolution of biological and morphologic hepatic parameters of iron overload.

Four baboons receiving intramuscular iron for 15 months were compared with two control baboons. From the overall two-year observation period the following data emerge: (1) The baboon is a suitable animal for obtaining a massive and chronic iron overload. Liver iron concentrations reached very high levels (ranging from 41.3 to 180.6 mumol/100 mg dry weight vs 1.7 +/- 0.5, mean +/- SEM, in controls), and a major liver iron overload (ie, with concentration values greater than or equal to 18) was present in all four animals for an average period of 16.5 months (range 14-19). (2) When compared with human hepatic iron-overload disorders, iron distribution was similar to that observed in secondary (transfusional) hepatic siderosis since iron deposits were found primarily in sinusoidal cells. However, a marked parenchymal siderosis was also obtained close to that observed in primary (genetic) siderosis. Iron toxicity was present biologically as indicated by an increase in serum transaminases. Histologically, a slight fibrosis was observed in the most heavily iron-overloaded baboon. On the whole, this study of subhuman primates brings new evidence that iron per se has only a minor hepatic damaging effect. It also suggests that the iron-overloaded baboon liver provides a promising tool for the study of liver cell disturbances in human iron overload.

Animals↗
PubMed2006

Evolution of biological and synthetic grafts in reconstructive pelvic surgery.

Surgery is an evolving science in the attempt to make surgical procedures more effective, safer, and less invasive. Recurrence and subsequent re-operation for stress incontinence and prolapse has been reported to be necessary in one of three patients, so there is a need for improvement [1]. In reconstructive pelvic surgery (RPS), the use of biological and synthetic grafts for the transabdominal and transvaginal treatment of pelvic organ prolapse (POP) or stress urinary incontinence (SI) has improved long-term support and function after surgery. However, the potential benefits of using grafts need to be carefully balanced against the risks of using materials foreign to the patient's body. Pelvic organ prolapse develops secondary to defective endopelvic fascial and muscular support. The levator ani provides resting tonic muscular support for all three pelvic compartments. Once neuromuscular damage occurs, extra strain is placed on the connective tissue supports, which may also subsequently fail. To date, there is no surgery that adequately addresses the issue of neuromuscular damage of the pelvic floor musculature. In conventional POP surgery, defective support is repaired by suturing of the patient's own connective tissue, fascia, or ligaments. The rationale for the use of grafts is to reinforce and strengthen pelvic organ repairs similar to the use of grafts to strengthen abdominal hernia repair.

Biocompatible Materials↗
PubMed2004

Evolution of biological effects of Aznalcóllar mining spill in the Algerian mouse (Mus spretus) using biochemical biomarkers.

The status of Guadiamar stream, polluted in 1998 by metals spilled from a pyrite tailings dam, was monitored from 1999 to 2001 to assess possible biological effects in terrestrial ecosystems of Doñana National Park (DNP) (Andalusia, SW Spain). The Algerian mouse (Mus spretus) was used as bioindicator at different Guadiamar and Doñana sites. Eleven biochemical parameters, including the activities of antioxidative and biotransforming enzymes and oxidative damages to biomolecules, were assayed in liver as biomarkers responsive to metals and organic pollutants. In 2001, metals were also determined in kidney and their possible correlation with biomarker responses was studied. Contents of Pb, Cd and As significantly correlated with several antioxidative enzymes. Biomarkers responsive to oxidative stress indicate the presence of transition metals in the high and medium Guadiamar course, and their response diminished with the distance to the collapsed dam. The high ethoxyresorufin-O-deethylase (EROD) activity of mice from the medium and low Guadiamar course point to organic pollutants, such as the pesticides used in intensive crops grown in areas nearby Doñana. The increasing responses of several biomarkers at reference sites may suggest a progressive pollution of key Doñana ecosystems.

Animals↗
PubMed1997

Artemia mitochondrial genome: molecular biology and evolutive considerations.

During the last two decades an increasing amount of information has been accumulated regarding the gene structure and organization of the mitochondrial genome from various organisms. Many studies carried out mainly in mammals, have contributed to the knowledge of the basic elements involved in the replication and transcription of mitochondrial DNA. However, very little is known about these processes in invertebrates. In this review we discuss our current knowledge of the animal mitochondrial genetic system and briefly summarize the structure of the Artemia mitochondrial genome, the characteristics of its transcriptional machinery and how its expression is controlled during early development, in relation with what is known in other organisms. Artemia is the only crustacean where the mtDNA has been studied at this level of detail up to date.

Animals↗
PubMedDate not supplied

A chemical index inspired by biological plastic evolution: valence-isoelectronic series of aromatics.

Plastic evolution is a new perspective of the evolutionary process conjugating the effect, on one hand, of the acquired characters and, on the other, of the relationships that emerge among the principle of evolutionary indeterminacy, the principle of morphologic determination, and natural selection. Plastic evolution is applied to design the coordination index Ic. Ic is used to characterize the valence-isoelectronic series of cyclopentadiene, benzene, toluene, and styrene and compared to charge indices for dipole moment. The parameters needed to calculate Ic are minus the standard enthalpy of formation T, molecular surface area S, and molecular weight W. With the exception of the O heteromolecule, Ic allows differentiating quantitatively the styrene series as well as the cyclopentadiene from the toluene series. Ic improves the multivariable regression equations for dipole moment and is a predictive index when it is used together with the topological charge indices. The correction introduced in the dipole moment is produced in the correct direction. Inclusion of the heteroatom in the pi-electron system is beneficial for the description of the dipole moment, owing to either the role of additional p and/or d orbitals provided by the heteroatom or the role of steric factors in the pi-electron conjugation. Principal component analysis groups the chemical indices in three classes, which are in agreement with cluster analysis.

Journal Article↗
PubMed2006

Avian and canine aldehyde oxidases. Novel insights into the biology and evolution of molybdo-flavoenzymes.

Aldehyde oxidases are molybdo-flavoenzymes structurally related to xanthine oxidoreductase. They catalyze the oxidation of aldehydes or N-heterocycles of physiological, pharmacological, and toxicological relevance. Rodents are characterized by four aldehyde oxidases as follows: AOX1 and aldehyde oxidase homologs 1-3 (AOH1, AOH2, and AOH3). Humans synthesize a single functional aldehyde oxidase, AOX1. Here we define the structure and the characteristics of the aldehyde oxidase genes and proteins in chicken and dog. The avian genome contains two aldehyde oxidase genes, AOX1 and AOH, mapping to chromosome 7. AOX1 and AOH are structurally very similar and code for proteins whose sequence was deduced from the corresponding cDNAs. AOX1 is the ortholog of the same gene in mammals, whereas AOH represents the likely ancestor of rodent AOH1, AOH2, and AOH3. The dog genome is endowed with two structurally conserved and active aldehyde oxidases clustering on chromosome 37. Cloning of the corresponding cDNAs and tissue distribution studies demonstrate that they are the orthologs of rodent AOH2 and AOH3. The vestiges of dog AOX1 and AOH1 are recognizable upstream of AOH2 and AOH3 on the same chromosome. Comparison of the complement and the structure of the aldehyde oxidase and xanthine oxidoreductase genes in vertebrates and other animal species indicates that they evolved through a series of duplication and inactivation events. Purification of the chicken AOX1 protein to homogeneity from kidney demonstrates that the enzyme possesses retinaldehyde oxidase activity. Unlike humans and most other mammals, dog and chicken are devoid of liver aldehyde oxidase activity.

Aldehyde Oxidase↗
PubMedDate not supplied

Evolution of biologic therapies for the treatment of psoriasis.

Over the past three decades, laboratory and clinical research findings have shown that T cells are the primary mediators of psoriasis pathogenesis and that psoriasis can be treated by eliminating these T cells or interfering with their activation or activity. Based on these observations, many new biologic therapies to treat psoriasis are now in development. These agents, developed primarily through recombinant DNA techniques, are designed to target T cells and the immunologic cascade associated with their activation. Four basic strategic approaches that focus on the steps involved in the immunopathology of psoriasis are: 1) elimination of the pathogenic T cells; 2) inhibition of T-cell activation, proliferation, and migration; 3) immune deviation to down-regulate the type 1 (TH1) response predominant in psoriasis; and 4) blockade of cytokine production. The goal of these new therapies is to improve the treatment of psoriasis, particularly moderate to severe disease, with agents that are well tolerated and safe for long-term use.

Biological Therapy↗
PubMed2003

Scanning probe evolution in biology.

Twenty years ago the first scanning probe instrument, the scanning tunneling microscope, opened up new realms for our perception of the world. Atoms that had been abstract entities were now real objects, clearly seen as distinguishable individuals at particular positions in space. A whole family of scanning probe instruments has been developed, extending our sense of touching to the scale of atoms and molecules. Such instruments are especially useful for imaging of biomolecular structures because they can produce topographic images with submolecular resolution in aqueous environments. Instruments with increased imaging rates, lower probe-specimen force interactions, and probe configurations not constrained to planar surfaces are being developed, with the goal of imaging processes at the single-molecule level-not only at surfaces but also within three-dimensional volumes-in real time.

Biology↗