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PubMedDate not supplied

[The involvement of the respiratory apparatus in leukemias].

In 13 cases of leukemia, different clinical forms showed pleuropulmonary and mediastinal lesions consisting in: mediastinal-hilar adenopathies without the parenchyma involvement (2 cases), with involvement of the pulmonary parenchyma (6 cases) and only one case of pulmonary lesions without adenopathies. In 3 cases leukemia overlapped pulmonary TB, TB sequela (2 cases) or active-evolutive TB (1 case). One case developed to bronchopulmonary neoplasm. While the treatment of parenchymatous complications, appeared by nonspecific infections, and of the single case of active tuberculosis proved adequate, the ganglionic-mediastinal lesions continued their acute or chronic unfavourable evolution.

Adult↗

PubMed2006

Rate of viral evolution and risk of losing future drug options in heavily pretreated, HIV-infected patients who continue to receive a stable, partially suppressive treatment regimen.

BACKGROUND: Many treatment-experienced, HIV-infected patients who have limited therapeutic options for complete viral suppression continue to receive a partially suppressive treatment regimen pending the availability of at least 2 new antiretroviral drugs. The major risk of this approach is ongoing viral evolution and the loss of future drug options. METHODS: Antiretroviral-treated subjects with incomplete viral suppression were sampled from a clinic-based cohort. Inclusion criteria were receipt of a stable treatment regimen for > or = 120 days, a plasma HIV RNA load of > 500 copies/mL, and > or = 1 resistance mutation. Phenotypic and genotypic resistance testing was performed every 4 months. RESULTS: The 106 patients who were eligible for the study had a median of 3 observations during a median of 11.3 months. An estimated 23% and 18% developed at least 1 new nucleoside analogue and 1 new protease inhibitor mutation at 1 year, respectively. An estimated 30% lost the phenotypic equivalent of 1 susceptible drug at 1 year. A lower number of total mutations at baseline was a significant predictor of developing a new nucleoside analogue mutation (P=.01). At 1 year, the probability that an existing mutation would become undetectable using population-based sequencing was 32%. There was a higher rate of change at nonresistance codons than at codons known to be associated with drug resistance. CONCLUSIONS: Heavily pretreated patients with HIV infection who remain on a partially suppressive regimen have a measurable risk of losing future drug options, particularly those patients who have few baseline mutations. Resistance mutations vary over time, which suggests that the results of any single resistance test may not be representative of all mutations selected by a given treatment regimen.

Anti-HIV Agents↗

PubMed1999

Yeast genome evolution in the post-genome era.

The Saccharomyces cerevisiae genome sequence, augmented by new data on gene expression and function, continues to yield new findings about eukaryote genome evolution. Analysis of the duplicate gene pairs formed by whole-genome duplication indicates that selection for increased levels of gene expression was a significant factor determining which genes were retained as duplicates and which were returned to a single-copy state, possibly in addition to selection for novel gene functions. Proteome comparisons between worm and yeast show that genes for core metabolic processes are shared among eukaryotes and unchanging in function, while comparisons between different yeast species identify 'orphan' genes as the most rapidly evolving fraction of the proteome. Natural hybridisation among yeast species is frequent, but its long-term evolutionary significance is unknown.

Evolution, Molecular↗

PubMed1993

Contributions to the history of psychology: XCV. Possible relations between theories of evolution and animal learning.

It is proposed that the dominance of continuity learning theory as set against noncontinuity learning theory during the middle third of the 20th century rested importantly on its derivation from Darwin's theory of evolution. The kinship is shown in several ways. First, Thorndike and Hull echoed the principle of natural selection in their belief that behaviors underwent gradual modification because acts that were attended steadily by favorable consequences tended to occur with increasing frequency. Second, they denied both nonphysical explanations of behavior and a priori purposes which might guide that behavior. Third, the laws of learning were said to hold for all organisms. It is argued that the continuity approach may have enjoyed success because it was consistent with the Darwinian world view. Had punctualist, rather than gradualist, explanations of evolution come to the fore in the late 19th century, learning theories might have proceeded quite differently with the dominance of non-continuity approaches.

Animals↗

PubMed2004

Recursion equations in predicting band width under gradient elution.

The evolution of solute zone under gradient elution is a typical problem of non-linear continuity equation since the local diffusion coefficient and local migration velocity of the mass cells of solute zones are the functions of position and time due to space- and time-variable mobile phase composition. In this paper, based on the mesoscopic approaches (Lagrangian description, the continuity theory and the local equilibrium assumption), the evolution of solute zones in space- and time-dependent fields is described by the iterative addition of local probability density of the mass cells of solute zones. Furthermore, on macroscopic levels, the recursion equations have been proposed to simulate zone migration and spreading in reversed-phase high-performance liquid chromatography (RP-HPLC) through directly relating local retention factor and local diffusion coefficient to local mobile phase concentration. This new approach differs entirely from the traditional theories on plate concept with Eulerian description, since band width recursion equation is actually the accumulation of local diffusion coefficients of solute zones to discrete-time slices. Recursion equations and literature equations were used in dealing with same experimental data in RP-HPLC, and the comparison results show that the recursion equations can accurately predict band width under gradient elution.

Chromatography, High Pressure Liquid↗

PubMed2006

Stochastic cancer progression driven by non-clonal chromosome aberrations.

Cancer research has previously focused on the identification of specific genes and pathways responsible for cancer initiation and progression based on the prevailing viewpoint that cancer is caused by a stepwise accumulation of genetic aberrations. This viewpoint, however, is not consistent with the clinical finding that tumors display high levels of genetic heterogeneity and distinctive karyotypes. We show that chromosomal instability primarily generates stochastic karyotypic changes leading to the random progression of cancer. This was accomplished by tracing karyotypic patterns of individual cells that contained either defective genes responsible for genome integrity or were challenged by onco-proteins or carcinogens that destabilized the genome. Analysis included the tracing of patterns of karyotypic evolution during different stages of cellular immortalization. This study revealed that non-clonal chromosomal aberrations (NCCAs) (both aneuploidy and structural aberrations) and not recurrent clonal chromosomal aberrations (CCAs) are directly linked to genomic instability and karyotypic evolution. Discovery of "transitional CCAs" during in vitro immortalization clearly demonstrates that karyotypic evolution in solid tumors is not a continuous process. NCCAs and their dynamic interplay with CCAs create infinite genomic combinations leading to clonal diversity necessary for cancer cell evolution. The karyotypic chaos observed within the cell crisis stage prior to establishment of the immortalization further supports the ultimate importance of genetic aberrations at the karyotypic or genome level. Therefore, genomic instability generated NCCAs are a key driving force in cancer progression. The dynamic relationship between NCCAs and CCAs provides a mechanism underlying chromosomal based cancer evolution and could have broad clinical applications.

Animals↗

PubMed2005

Measurement of turbulence decorrelation during transport barrier evolution in a high-temperature fusion plasma.

A low power polychromatic beam of microwaves is used to diagnose the behavior of turbulent fluctuations in the core of the JT-60U tokamak during the evolution of the internal transport barrier. A continuous reduction in the size of turbulent structures is observed concomitant with the reduction of the density scale length during the evolution of the internal transport barrier. The density correlation length decreases to the order of the ion gyroradius, in contrast with the much longer scale lengths observed earlier in the discharge, while the density fluctuation level remain similar to the level before transport barrier formation.

Journal Article↗

PubMed1986

[Changes in thyroid function caused by continuous treatment with thiouracil in rats].

Serum concentration evolution of thyroxine and triiodothyronine, and thyrotropin (TSH), have been studied in rats while they were given 6-propylthiouracil (PTU) as antithyroid drug, and during the recovery period after suppression of treatment. In the same way thyroid hypertrophy and plasmatic levels of thyrotropin were correlated. Animals received orally a daily dose of 1 mg/100 g body weight during thirty-five days and had a two week recovery period. Thyroid hormone concentrations in plasma were determined by immunoenzymatic assay ELISA with peroxidase as labelled enzyme. From the results obtained, it can be stated that chronic administration of PTU implies a continuous decrease in thyroid hormone concentrations in plasma, reaching nearly zero values, while after treatment, levels recover their normal values in a week's time. A parallelism exists between thyroid hypertrophy and pituitary TSH hypersecretion, due to a decrease in thyroid hormone levels.

Animals↗

PubMed2003

The effect of light:dark cycles of medium frequency on photosynthesis by Chlorella vulgaris and the implications for waste stabilisation pond design and performance.

The effect of light/dark (L:D) cycle times on the recovery from photoinhibition of green micro-alga Chlorella vulgaris (CCAP211/11c) and the cyanobacterium Synechococcus (CCAP1479/5) was investigated using an irradiated, temperature controlled oxygen electrode. The onset of photoinhibition in both organisms occurred at irradiances > 300 micromol m(-2)s(-1) at temperatures >15 degrees C. Light/dark cycle times were controlled independently using a relay timer and shutter placed between the quartz iodide light source and the oxygen electrode chamber. Oxygen evolution decreased rapidly when cells were continuously irradiated at 300, 500 and 750 micromol m(-2)s(-1). However, Chlorella cells irradiated at 300, 500 and 750 micromol m(-2)s(-1)on a L:D cycle of 60s:20s, 30s:60s and 60s: 120s respectively, maintained a constant rate of oxygen evolution over a 24 h incubation period. Exposure time to a given incident irradiance rather than the total light dose received appeared to determine the effect of light/dark cycle times on photosynthesis. A relationship was established between L:D ratio required to maintain constant oxygen production and incident photon flux density. The results suggest that the adverse effects of high irradiances on algae near the surface of a stratified waste stabilisation pond might be ameliorated by controlled mixing of algal cells through the depth of the pond.

Bioreactors↗

PubMed2005

Multistep skin cancer in mice as a model to study the evolution of cancer cells.

Although much of cancer research relies on Nowell's clonal evolution hypothesis as a conceptual framework, large gaps remain in understanding how tumors develop. The multistage skin cancer model in mice provides continuing insight on fundamental aspects of tumor evolution. In this model, mutation of the oncogene Hras is frequently the initiating event while mutation of the tumor suppressor p53 is a late event, associated with malignant progression. Recent evidence demonstrates that intracellular signaling from the initial Hras mutation leads directly to the activation of p53, creating selective pressure in favor of cells with mutant p53. Thus, selection for subsequent mutations is mechanistically linked to the initial mutation, explaining the preferred order of mutational events observed. Analysis of this model also reveals that a diverse array of signals can selectively impair or enhance clonal expansion of Ras mutant cells into a visible neoplasm. These modifiers can be genetic, physiological, or environmental and are often highly specific to tumor cells. This indicates that tumor cells have an inherent reduced capacity to buffer against perturbations. Reduced buffering may play an important role in both tumor evolution and therapy response and may be a hallmark of cancer cells.

Animals↗

PubMed1990

Independent and disparate evolution in nature of influenza A virus hemagglutinin and neuraminidase glycoproteins.

The hemagglutinin (HA) and neuraminidase (NA) external glycoprotein antigens of H1N1 and H3N2 subtypes of epidemiologically important influenza A viruses prevalent during recent decades were subjected to intensive antigenic analysis by four different methods. Prior to serological analysis with polyclonal rabbit antisera, HA and NA antigens of four viruses of each subtype were segregated by genetic reassortment to forestall nonspecific steric hindrance during antigen-antibody combination. This analysis has demonstrated that with respect to antigenic phenotype, HA and NA proteins have evolved at different rates. With H1N1 viruses, an arrest of significant evolution of the NA discordant with the continuing antigenic drift of HA was found in the 1980-1983 period. It is probable that the different and independent rates of evolution of HA and NA reflect the greater selective pressure of HA antibodies, which forces the more rapid emergence of HA escape mutants. The slower antigenic change found for NA further supports the potential for NA-specific infection-permissive immunization as a useful stratagem against influenza.

Biological Evolution↗

PubMed2004

Neanderthal taxonomy reconsidered: implications of 3D primate models of intra- and interspecific differences.

The taxonomic status of Neanderthals lies at the center of the modern human origins debate. Proponents of the single-origin model often view this group as a distinct species with little or no contribution to the evolution of modern humans. Adherents to the regional continuity model consider Neanderthals a subspecies or population of Homo sapiens, which contributed significantly to the evolution of early modern Europeans. Paleontologists generally agree that fossil species should be equivalent to extant ones in the amount of their morphological variation. Recognition of fossil species therefore hinges on analogy to living species. A previous study by one of the authors and recent work by other researchers [Schillachi, M. A. & Froelich, J. W. (2001) Am. J. Phys. Anthropol. 115, 157-166] have supported specific status for Neanderthals based on analogy to chimpanzees and Sulawesi macaques, respectively. However, these taxa may not be the most appropriate models for Pleistocene humans. Here we test the hypothesis that Neanderthals represent a subspecies of H. sapiens by comparing the degree of their morphological differentiation from modern humans to that found within and between 12 species of extant primates. The model taxa comprised >1,000 specimens, including phylogenetic (modern humans and African apes) and ecological (eight papionin taxa) models for Pleistocene humans. Morphological distances between model taxon pairs were compared to the distances between Neanderthals and modern humans obtained by using a randomization technique. Results strongly support a specific distinction for Neanderthals.

Animals↗

PubMed1996

Treatment of CAPD-related peritonitis with ciprofloxacin: results after seven years.

We present the results of a protocol of empiric monotherapy of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis with ciprofloxacin (CPX), with a special emphasis on the evolution of our results after seven years of continued use of this drug. One hundred and fifteen episodes of bacterial peritonitis were treated with CPX between 1988 and 1992 (group A), and 115 episodes were treated between 1993 and 1995 (group B). The etiologic spectrum of peritonitis was similar in both groups, except for a higher incidence of polymicrobial infections in group B. The clinical success rate decreased from 86.5% in group A to 75% in group B (p < 0.05). This was partly due to the high failure rate of CPX against polymicrobial peritonitis, but the success rate also tended to decrease for gram-positive and, especially, gram-negative bacteria. However, in vitro sensitivity to CPX decreased only for coagulase-negative staphylococci, remaining stable for Staphylococcus aureus and gram-negative bacteria. CPX is still a valid alternative for the treatment of CAPD-related peritonitis in our unit. However, bacterial sensitivity must be closely monitored, especially in the case of coagulase-negative staphylococci. A different therapeutic approach may be indicated if polymicrobial peritonitis is suspected.

Anti-Infective Agents↗

PubMed1989

Divergent evolution of part of the involucrin gene in the hominoids: unique intragenic duplications in the gorilla and human.

The gene for involucrin, an epidermal protein, has been remodeled in the higher primates. Most of the coding region of the human gene consists of a modern segment of repeats derived from a 10-codon sequence present in the ancestral segment of the gene. The modern segment can be divided into early, middle, and late regions. We report here the nucleotide sequence of three alleles of the gorilla involucrin gene. Each possesses a modern segment homologous to that of the human and consisting of 10-codon repeats. The early and middle regions are similar to the corresponding regions of the human allele and are nearly identical among the different gorilla alleles. The late region consists of recent duplications whose pattern is unique in each of the gorilla alleles and in the human allele. The early region is located in what is now the 3' third of the modern segment, and the late, polymorphic region is located in what is now the 5' third. Therefore, as the modern segment expanded during evolution, its 3' end became stabilized, and continuing duplications became confined to its 5' end. The expansion of the involucrin coding region, which began long before the separation of the gorilla and human, has continued in both species after their separation.

Animals↗

PubMed1998

Crucial crises in biology: life in the deep biosphere.

The origin and evolution of life on Earth are the result of a series of crises that have taken place on the planet over about 4500 millions of years since it originated. Biopoiesis (origin of life), ecopoiesis (origin of ecosystems) and the first ecosystems (stromatolites and microbial mats), as well as eukaryopoiesis (origin of nucleated cells) are revised. The paper then focuses on the study of the deep biosphere, describing ecosystems never found before, which are independent of solar radiation and have changed previous assumptions about the requirements of life; even the concept of biosphere, as Vernadsky defined it, has increased its scope. Since the discovery, in 1987, of bacteria growing in the crevices of rocks at 500 m deep, in boreholes drilled near the Savanna River, Aiken, South Carolina, other bacteria have been found in the deep subsurface reaching depths of about 3 km (e.g., in the Columbia River Basalt Group, near Richland, Washington state), in an anaerobic, hot, high-pressure environment. Some kinds of microorganisms can thrive at such depths, living in many cases a geochemical existence, by using very specialized metabolisms, which depend on the local environments. The existence of organisms independent from photosynthetic production is the most outstanding, novel feature of the deep biosphere. Living beings might not need other energy and chemical sources than those which occur in the development of all planetary bodies. Life, therefore, could even be an ineluctable outcome of planetary evolution and, as a corollary, a natural continuation of the usual development of physical phenomena in the universe.

Atmosphere↗

PubMed2001

Reinforcement of genetic coherence in a two-locus model.

BACKGROUND: In order to maintain populations as units of reproduction and thus enable anagenetic evolution, genetic factors must exist which prevent continuing reproductive separation or enhance reproductive contact. This evolutionary principle is called genetic coherence and it marks the often ignored counterpart of cladistic evolution. Possibilities of the evolution of genetic coherence are studied with the help of a two-locus model with two alleles at each locus. The locus at which viability selection takes place is also the one that controls the fusion of gametes. The second locus acts on the first by modifying the control of the fusion probabilities. It thus acts as a mating modifier whereas the first locus plays the role of the object of selection and mating. Genetic coherence is enhanced by modifications which confer higher probabilities of fusion to heterotypic gametic combinations (resulting in heterozygous zygotes) at the object locus. RESULTS: It is shown that mutants at the mating modifier locus, which increase heterotypic fusions but do not lower the homotpyic fusions relative to the resident allele at the object locus, generally replace the resident allele. Since heterozygote advantage at the object locus is a necessary condition for this result to hold true, reinforcement of genetic coherence can be claimed for this case. If the homotypic fusions are lowered, complex situations may arise which may favor or disfavor the mutant depending on initial frequencies and recombination rates. To allow for a generalized analysis including alternative models of genetic coherence as well as the estimation of its degrees in real populations, an operational concept for the measurement of this degree is developed. The resulting index is applied to the interpretation of data from crossing experiments in Alnus species designed to detect incompatibility relations.

Alleles↗

PubMed1982

Biochemical response to change in the environment and the nature of "essential" hypertension.

The abnormality of Na+, K+-cotransport detected in erythrocytes of patients with "essential" hypertension, appears to be an inherited biochemical disorder characteristic of the disease. This explains several features of "essential" hypertension. However, characteristics of the kinetics of this Na+ transport system are similar to characteristics of enzymes in halophilic organisms, which live in a high saline environment. Cell Na+ is increased in patients with "essential" hypertension and in halophilic organisms. This suggests that the enzyme characteristics are response mechanisms to maintain extracellular Na+ concentration within an optimal range. Based on this view two assumptions of biochemical response have been put forward which form the biochemical basis of a general biological theory. The implications of this for understanding the nature of "essential" hypertension are discussed. To explain the nature of the inheritance of the Na+, K+-cotransport defect in erythrocytes of patients with "essential" hypertension, a theory of acquired genetic transmission called "improvisation" theory is proposed. Improvisation may be the mechanism whereby new gene formation occurs, and be the mechanism for evolution of species if successful reproduction of offspring is allowed to continue.

Adaptation, Physiological↗

PubMed2005

Was Darwin a creationist?

Throughout the Origin of Species, Darwin contrasts his theory of natural selection with the theory that God independently created each species. This makes it seem as though the Origin offers a scientific alternative to a theological worldview. A few months after the Origin appeared, however, the eminent anatomist Richard Owen published a review that pointed out the theological assumptions of Darwin's theory. Owen worked in the tradition of rational morphology, within which one might suggest that evolution occurs by processes that are continuous with those by which life arises from matter; in contrast, Darwin rested his account of life's origins on the notion that God created one or a few life forms upon which natural selection could act. Owen argued that Darwin's reliance on God to explain the origins of life makes his version of evolution no less supernatural than the special creationist that Darwin criticizes: although Darwin limits God to one or a few acts of creation, he still relies upon God to explain life's existence.

Biological Evolution↗