[Evolution and the methodology of the biological sciences].
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Anatomy↗
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Results for “Biological Evolution”
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Evolution of immunologic functions of the mammary gland and the postnatal development of immunity.
Physiologic delays in production of immune factors occur in mammals including Homo sapiens. This finding is counter to a basic tenet of biologic evolution, because such delays increase the risk of infections. The disadvantage is, however, offset by defense factors in milk of the species in whom the developmental delay occurs. Reciprocal relationships between the production of immune factors by the lactating mammary gland and the production of those defense agents during early infancy are found in all investigated mammalian species. Thus, the evolution of these processes is closely related. Certain immunologic components of milk are highly conserved, whereas others vary according to the species. The variations most likely evolved by genetic mutations and natural selection. In addition, the immune composition of mammalian milks is associated with developmental delays in the same immunologic agents. Furthermore, most closely related mammals, such as humans and chimpanzees, are most similar in the defense agents in their milks and the corresponding developmental delays in their immune systems. Defense factors in human milk include antimicrobial agents (secretory IgA, lactoferrin, lysozyme, glycoconjugates, oligosaccharides, and digestive products of milk lipids), antiinflammatory factors (antioxidants, epithelial growth factors, cellular protective agents, and enzymes that degrade mediators of inflammation), immunomodulators (nucleotides, cytokines, and antiidiotypic antibodies), and leukocytes (neutrophils, macrophages, and lymphocytes). Because of a lack of geographic/ethnic variation in the immunologic composition of human milk and corresponding immunologic delays in infants, these evolutionary processes seem stable. This is supported by investigations of diverse populations that indicate that this evolutionary outcome is highly beneficial to human infants.
Animals↗
The evolution strategy--a search strategy used in individual optimization of electrical parameters for therapeutic carotid sinus nerve stimulation.
Optimization problems, arising in the search for parameters and/or techniques of functional electrostimulation (FES), disproportionally increase when multiple electrodes, electrode configurations, electrical parameters, and stimulation modes may be applied. When computational or investigational effort precludes systematic studies in FES, we propose to apply and evaluate Rechenberg's evolution strategy, which in technical use and numerical optimization has been valid in comparison to more traditional methods. This strategy implements mutation and selection processes in analogy to biological evolution. The effect of combined multiple input variables on a quality function (Q) is experimentally evaluated. The actual computed value of Q serves as a selection criterion for those input variable combinations which lead Q to approach a target value (maximization), similar to a hill-climbing procedure. In radiofrequency controlled, therapeutic electrical carotid sinus nerve stimulation (CSNS), we varied (mutated) combinations of pulse frequency and pulse amplitude parameters, according to the evolution strategy, in individual patients. CSNS lowers blood pressure and decreases heart rate. Q was computed from blood pressure and heart rate responses to CSNS. The strategy individually optimized electrical parameters to achieve large depressor responses upon CSNS. Although, in contrast to technical usage, only two input variables were investigated, and biomedical experience with the evolution strategy is limited so far, its potential use in other fields of FES, especially when more input variables are to be optimized, is discussed and encouraged.
Algorithms↗
Chemistry of the interstellar medium--an evolutionary dead end?
An analysis of the experimental data available and of the present theoretical concepts shows that even the initial physicochemical chemical precellular stages of biological evolution are impossible in the interstellar medium, while biomonomers possibly formed on asteroids and comets might have participated after transportation to the Earth in the final stages of the origin of the first precellular biological structures and then in the first living cells.
Aluminum Silicates↗
Longitudinal study of 94 symptomatic infants with perinatally acquired human immunodeficiency virus infection. Evidence for a bimodal expression of clinical and biological symptoms.
To better define the clinical and biological evolution of infants after vertical human immunodeficiency virus type 1 infection, we analyzed 94 consecutive infected patients followed up after their first clinical symptoms. The expression of clinical symptoms and biological abnormalities followed a bimodal distribution, some patients having an early and severe disease and the others having a slowly progressive one. One third of our patients suffered from early onset of opportunistic infection (OI). These patients had a significantly higher incidence of severe encephalopathy compared with patients without OI. The rate of survival at 3 years was 48% +/- 24%. In contrast, the patients without early OI or severe encephalopathy had a probability of survival at 3 years of 97% +/- 3%. This probability was not modified by the occurrence of bacterial infection or lymphoid interstitial pneumonitis. Lymphoid interstitial pneumonitis occurred at a mean age of 29 months, significantly later than OI or severe encephalopathy. Laboratory results at initial examination were correlated with clinical symptoms. Thus, when the number of CD4 lymphocytes was less than 500/mm3, children suffered more frequently from life-threatening symptoms (OI and severe encephalopathy): 15 of 22 vs 14 of 69. The same was true when the lymphocytes did not proliferate after antigenic stimulation, when anti-p18 and/or anti-p25 antibodies were absent in the serum, and when p24 antigen was detected in serum. Finally, severe encephalopathy was associated with low anti-human immunodeficiency virus cerebrospinal fluid antibody titer, whereas 88% of patients with moderate or no encephalopathy had signs of intrathecal anti-human immunodeficiency virus antibody synthesis. In conclusion, a subgroup of patients expressed very early signs of severe immunodeficiency and encephalopathy, whereas the majority of patients had a longer survival and less severe clinical symptoms during their first years of life than previously thought.
AIDS Dementia Complex↗
Closure and anticlosure in the realm of quantum gravity. Why evolution needs no origin
Dynamic systems with suitable nonlinearities yield self-organizing behavior. The evolution continues until the relationship among the components becomes self-consistent; that is, until it reaches closure. Disruptions of closure that allow for continued change are also characteristic of biological evolution. Are the requisite nonlinearities add-ons that give an essentially linear world the appearance of circularity, or do they have their origin in the underlying physics of the universe? The picture developed here fits to the latter view.
Journal Article↗
[Lamarck, Darwin and modern biology].
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Biological Evolution↗
[Biological effects of nonionizing radiation: low frequency electromagnetic fields].
This article reviews various studies on effects of electric and magnetic fields of extremely low frequencies on human health and gives an overview of residential and occupational exposure to different sources, currently established exposure limitations, and protection measures. Throughout the evolution biological systems adapted to natural electric and magnetic fields. Only hundred years ago human exposure to radiation was limited to electric and magnetic fields arising either from extraterrestrial or terrestrial sources, yet both natural. For the past fifty years there has been large growth of artificial sources of electric and magnetic fields, especially with frequencies of 50 and 60 Hz (power generating and distribution systems). The concern about long-term exposure to artificial fields and possible adverse effects on human health has been entirely justified and led to numerous intensive epidemiological and laboratory studies. Results of several epidemiological studies confirm the connection between exposure to electric and magnetic fields of extremely low frequencies (up to 300 Hz) and increased risk of leukemia and brain tumor in children and adults. In addition, the risk of breast cancer in occupationally exposed population has increased. Laboratory studies on animal models, in vitro systems, and human volunteers did not confirm this connection. There is a growing interest in investigation of other possible adverse health effects such as neurodegenerative diseases (Alzheimer's disease and other forms of dementia, amyotrophic lateral sclerosis), cardiovascular disorders (arrhythmias and acute myocardial infarction), psychiatric disorders, and electrosensitivity.
Animals↗
Deciphering principles of transcription regulation in eukaryotic genomes.
Transcription regulation has been responsible for organismal complexity and diversity in the course of biological evolution and adaptation, and it is determined largely by the context-dependent behavior of cis-regulatory elements (CREs). Therefore, understanding principles underlying CRE behavior in regulating transcription constitutes a fundamental objective of quantitative biology, yet these remain poorly understood. Here we present a deterministic mathematical strategy, the motif expression decomposition (MED) method, for deriving principles of transcription regulation at the single-gene resolution level. MED operates on all genes in a genome without requiring any a priori knowledge of gene cluster membership, or manual tuning of parameters. Applying MED to Saccharomyces cerevisiae transcriptional networks, we identified four functions describing four different ways that CREs can quantitatively affect gene expression levels. These functions, three of which have extrema in different positions in the gene promoter (short-, mid-, and long-range) whereas the other depends on the motif orientation, are validated by expression data. We illustrate how nature could use these principles as an additional dimension to amplify the combinatorial power of a small set of CREs in regulating transcription.
Computational Biology↗
The galactic habitable zone and the age distribution of complex life in the Milky Way.
We modeled the evolution of the Milky Way Galaxy to trace the distribution in space and time of four prerequisites for complex life: the presence of a host star, enough heavy elements to form terrestrial planets, sufficient time for biological evolution, and an environment free of life-extinguishing supernovae. We identified the Galactic habitable zone (GHZ) as an annular region between 7 and 9 kiloparsecs from the Galactic center that widens with time and is composed of stars that formed between 8 and 4 billion years ago. This GHZ yields an age distribution for the complex life that may inhabit our Galaxy. We found that 75% of the stars in the GHZ are older than the Sun.
Astronomical Phenomena↗
The pathology of cervical cancer.
The significant changes over the last decade in the CIN/cervical carcinoma area have involved the increasing recognition of many cervical carcinomas as adenocarcinomas, rather than squamous cell type, and their propensity for arising in young women. Another area of interest is the deployment of new molecular techniques that are unveiling the role of oncogene co-factors (e.g. HPV, p53) in the biologic evolution of CIN and hopefully glandular dysplasia.
Adenocarcinoma↗
Key-string algorithm--novel approach to computational analysis of repetitive sequences in human centromeric DNA.
AIM: To use a novel computational approach, Key-string Algorithm (KSA), for the identification and analysis of arbitrarily large repetitive sequences and higher-order repeats (HORs) in noncoding DNA. This approach is based on the use of key string that plays a role of an arbitrarily constructed "computer enzyme". METHOD: A cluster of novel KSA-related methods was introduced and developed on the basis of a combination of computations on a very modest scale, by eye inspection and graphical display of results of analysis. Sequence analysis software was developed, containing seven programs for KSA-related analyses. This approach was demonstrated in the case study of alpha satellites and HORs in the human genetic sequence AC017075.8 (193277 bp) from the centromeric region of human chromosome 7. The KSA segmentation method was applied by using DCCGTTT, GTA, and TTTC key strings. RESULTS: Fifty-five copies of 2734-bp 16mer HORs were identified and investigated, and a start-string TTTTTTAAAAA was identified. The HOR-matrix was constructed and employed for graphical display of mutations. KSA identification of HORs in AC017075.8 was compared with that of RepeatMasker and Tandem Repeat Finder, which identified alpha monomers in AC017075.8, but not the HORs. On the basis of KSA study, the centromere folding was described as an effect of HORs and super-HORs (3 x 2734 bp) in AC017075.8. The following novel computational KSA-based methods, easy-to-use and intended for computational "pedestrians", were demonstrated: color-HOR diagram, KSA-divergence method, 171-bp subsequence-convergence diagram, and total frequency distribution of the key-string subsequence lengths. The results were supplemented by Fast Fourier Transform, employing a novel mapping of symbolic genomic sequence into a numerical sequence. CONCLUSION: The KSA approach offers a simple and robust framework for a wide range of investigations of large repetitive sequences and HORs, involving a very modest scope of computations that can be carried out by using a PC. As the KSA method is HOR-oriented, the identification of HORs is even easier than the identification of underlying alpha monomer itself. This approach provides an easy identification of point mutations, insertions, and deletions, with respect to consensus. This may be useful in a wide range of investigations and applied in forensic medicine, medical diagnosis of malignant diseases, biological evolution, and paleontology.
Algorithms↗
URGE AND MOLECULAR BIOLOGY.
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Biochemical Phenomena↗
Extraction of phylogenetic network modules from the metabolic network.
BACKGROUND: In bio-systems, genes, proteins and compounds are related to each other, thus forming complex networks. Although each organism has its individual network, some organisms contain common sub-networks based on function. Given a certain sub-network, the distribution of organisms common to it represents the diversity of its function. RESULTS: We extracted such "common" sub-networks, defined as "phylogenetic network modules," using phylogenetic profiles and cluster analysis. The enzymes in the same "phylogenetic network module" have similar phylogenetic profiles and related functions. These modules are shown to be phylogenetic building blocks. Furthermore, the network of the modules illustrated hierarchical feature as well as the network of enzymes involved in the metabolism. CONCLUSION: We conclude that phylogenetic network modules are evolutionary conserved functional units in the metabolic network. We claim that our concept of phylogenetic modules provides a more accurate understanding of the evolution of biological networks.
Animals↗
Safety and efficacy of conservative management in acute severe pancreatitis.
Acute severe pancreatitis represents a disease with multiple complications and a high mortality rate. The clinical evolution is related to the acute systemic inflammatory response syndrome, due mainly to inflammatory mediators and pancreatic enzymes and to the infectious complications representing a peak in the incidence of death. This study aims to retrospectively analyse the outcome of patients diagnosed with acute severe pancreatitis, conservatively treated versus those surgically managed. This study includes 151 patients, each having been diagnosed with acute severe pancreatitis (CT using Balthazar's) distributed in term of age, sex and severity parameters. The conservative treatment has included antibiotics, and anti-inflammatory drugs. The imaging and biological parameters were further statistically analysed. The clinical-biological evolution has been paralleled by the CT severity index. The conservatively treated group had a better clinical-biological outcome (p<0.05), when compared with the surgically treated group. Morbidity was significantly higher in the group exposed to surgical treatment. Conservative treatment should be the first option in acute severe pancreatitis management.
Adult↗
Drug evolution concept in drug design: 2. Chimera method.
The drug evolution method represents a novel approach towards efficient rational drug design by implementing the drug evolution concept to the creation and development of general chemical libraries with the purpose of allowing the identification of drug candidates with improved odds and lesser costs than the traditional drug design strategies. As another example of successful translation of the biological evolution into chemical evolution, the chimera method comprises the grafting of selected building blocks, identified through a basic search within a drug library, onto the same substitution sites on a rationally chosen scaffold. The method allows the creation of a library containing both drugs and prospective drug candidates without any priorly required knowledge on the pursued disease or molecular target. Two libraries having scaffolds derived from para-aminobenzoic acid and salicylic acid have exemplified the application of the chimera method. The validation of the method has been achieved through the high number of recognized drugs within the library, which exhibit in the same time a wide variety of therapeutic activities and interact with a broad spectrum of molecular targets. The drug-enriched chimera libraries are expected to provide a highly efficient access to novel drug candidates whose unspecified therapeutic effects should be further revealed through high-throughput screening.
4-Aminobenzoic Acid↗
Acute intoxication by phenformine hyperlactatemia reversible with extra-renal purification.
The authors report the observation of an acute intoxication with 25.5 g of metaformin, 2.5 g of phenobarbital and 12.5 g of belladonna extract in a 53 year-old diabetic patient having been treated with metformin for 5 years. The evolution was dominated by the association of a barbituric coma with an hyperlactatemia which reached 21 mmol/l during the 18th hour and normalized at the 36th hour thanks to an hemodialysis on polyacrilonitrile membrane, which was carried out for 24 hours. The biological evolution was determined in considering the barbitemia, lactacidemia and metforminemia rates. An hepatic biopsy made during the decrease of the hyperlactatemia enabled to consider histological lesions of steatosis and ultrastructural lesions of mitochondrial alteration, already described in the course of pathological hyperlactatemia.
Humans↗