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PubMed1998

Opponent processes and anxiety: toward a neurophysiological formulation.

As a general philosophical framework, the author presents a theoretical position according to which 'opposition' is at the heart of the workings of the living being and the very origins of life. He then deals with 'opposing processes' and neural mechanisms which appear to underlie them. The theory rests on the premise that a great number of our actions are derived from our emotions, and that the coupling of pleasure/suffering controls the expression of our desires. Developed in the 1970s, this theory is founded on the observation of dependence phenomena (addictions), but its value extends far beyond drugs, to all types of human conduct, including sexuality, play, alimentary behaviours, etc. Inconsistent with classical theories, it subordinates the act to an affective state. The author finally examines the phenomenon of anxiety in the light of these considerations.

Animals↗
PubMed1999

Evolution of evolvability.

Genomic sequence data provide evidence for a common origin of life and for its evolution by genetic variation via mutation and recombination. This paper discusses the fundamental dialectic paradigm of evolution--stability versus variability--at the crossroads of molecular genetics, population genetics, ecology, and the emerging science of experimental evolution. Experimental evolution of molecules, viruses, and bacteria can be used not only to test some basic evolutionary hypotheses but also to create new organisms for applications in biotechnology, agriculture, and medicine.

Adaptation, Biological↗
PubMed2003

On the ordinality of causes in complex autocatalytic systems.

The convention in chemical dynamics usually is to identify the reactant and catalytic molecules as the active agencies that combine in mechanical fashion to constitute a reaction process. When macromolecules grow large and complex enough to exhibit some plasticity, however, the subsequent directions in which these molecules change may be guided more by the nexus of chemical reactions in which they participate. In particular, configurations of autocatalytic reactions among plastic macromolecules can come to exert more agency upon the component reactants and mechanisms than vice versa, and the nexus of such processes retains its identity longer than do the latter, more transient participants. Whence, the ascendancy of autocatalytic forms as causal agencies provides a natural example of the phenomenon of "emergence" and affords a way out of the conundrums that currently obfuscate the issue of the origin of life.

Journal Article↗
PubMed2004

The emergence of competition between model protocells.

The transition from independent molecular entities to cellular structures with integrated behaviors was a crucial aspect of the origin of life. We show that simple physical principles can mediate a coordinated interaction between genome and compartment boundary, independent of any genomic functions beyond self-replication. RNA, encapsulated in fatty acid vesicles, exerts an osmotic pressure on the vesicle membrane that drives the uptake of additional membrane components, leading to membrane growth at the expense of relaxed vesicles, which shrink. Thus, more efficient RNA replication could cause faster cell growth, leading to the emergence of Darwinian evolution at the cellular level.

Biological Evolution↗
PubMed1989

Template-directed oligomerization catalyzed by a polynucleotide analog.

A pyrophosphate-linked analog of polycytidylic acid has been synthesized and shown to catalyze the oligomerization of the complementary monomer 2'-deoxyguanosine 3',5'-bisphosphoimidazolide. Analogs of polynucleotides are of interest in studies of the origins of life as possible precursors of the first RNA molecules. These results demonstrate that such molecules are capable of serving as templates for further synthesis.

Catalysis↗
PubMed1994

Application and accuracy of molecular phylogenies.

Molecular investigations of evolutionary history are being used to study subjects as diverse as the epidemiology of acquired immune deficiency syndrome and the origin of life. These studies depend on accurate estimates of phylogeny. The performance of methods of phylogenetic analysis can be assessed by numerical simulation studies and by the experimental evolution of organisms in controlled laboratory situations. Both kinds of assessment indicate that existing methods are effective at estimating phylogenies over a wide range of evolutionary conditions, especially if information about substitution bias is used to provide differential weightings for character transformations.

Bacteriophage T7↗
PubMed1993

Inflammatory cells in the lungs of premature infants on the first day of life: perinatal risk factors and origin of cells.

Neither the origin of leucocytes in the premature newborn airway nor their relationship to perinatal factors has been adequately determined. In order to sample airway cells, modified bronchoalveolar lavage was performed on 74 intubated infants of < 32 weeks' gestation and < 24 hours of age. Cells were counted, stained and, in a small separate group of six infants, four boys and two girls, probed for the Y chromosome with suitable control samples. Perinatal risk factors for increased airway cellularity were analysed by multiple regression. Premature rupture of membranes of more than 24 hours' duration was independently associated with increased numbers of airway leucocytes (n = 74). More than 90% of airway leucocytes from four boys with pulmonary inflammation were positive for the Y chromosome indicating that the cells were of fetal rather than maternal origin.

Bronchoalveolar Lavage Fluid↗
PubMed1989

The neutral theory of molecular evolution and the world view of the neutralists.

The main tenet of the neutral theory is that the great majority of evolutionary changes at the molecular level are caused not by Darwinian selection but by random fixation of selectively neutral (or very nearly neutral) alleles through random sampling drift under continued mutation pressure. The theory also asserts that the majority of protein and DNA polymorphisms are selectively neutral, and that they are maintained in the species by mutational input balanced by random extinction rather than by "balancing selection." The neutral theory is based on simple assumptions. This enabled us to develop mathematical theories (using the diffusion equation method) that can treat these phenomena in quantitative terms and that permit theory to be tested against actual observations. Although the neutral theory has been severely criticized by the neo-Darwinian establishment, supporting evidence has accumulated over the last 20 years. In particular, the recent burst of DNA sequence data helped to strengthen the theory a great deal. I believe that the neutral theory triggered reexamination of the traditional "synthetic theory of evolution." In this paper, I review the present status of the neutral theory, including discussions of such topics as "molecular evolutionary clock," very high evolutionary rates observed in RNA viruses, a deviant coding system found in Mycoplasm together with the concept of mutation-driven neutral evolution, and the origin of life. I also present a worldview based on the conception of what I call "survival of the luckiest."

Animals↗
PubMed1993

The Sea of Life: a metaphorical vehicle for theory explication.

Metaphorical expression is viewed as a fundamental way of symbolizing used to develop nursing theory. The Sea of Life poem depicts a metaphor for explicating a theoretical structure derived from principles of the human becoming theory: Transforming occurs in the revealing-concealing of valuing. The Sea of Life, an original poem, sets forth the idea that unique meanings are co-created through human-environment relationships. The concepts of valuing, revealing-concealing, and transforming are linked through the poem to lived experiences. The easily recognizable concrete lived experiences which flow from the poem are re-conceptualized to formulate research questions.

Human Development↗
PubMed2004

Americo Negrette (1924 to 2003): diagnosing Huntington disease in Venezuela.

OBJECTIVE: To elucidate the role of Dr. Americo Negrette in diagnosing and reclassifying the dancing mania in Maracaibo, Venezuela as Huntington disease (HD). METHODS: All of the medical and nonmedical books and articles by Negrette were collected and reviewed. Personal interviews with Negrette were performed to confirm the details of his life and original work. His childhood, medical education, and contribution to HD, as well as contributions to medicine, art, and poetry, were covered in interview sessions. Excerpts from his autobiography, Ciudad de Fuego, were translated into English for publication. A complete bibliography of 70 books and research articles authored by Negrette was assembled. Negrette himself reviewed the compilation of this manuscript just days before his sudden death on September 14, 2003. RESULTS: Americo Negrette, a Venezuelan physician, biochemist, artist, and poet, observed a dancing epidemic in 1952. He acquired, through interviews with locals, the knowledge that there were two other small towns along Lake Maracaibo devastated by a syndrome called el mal (the bad). Negrette changed the diagnosis of these patients from a dancing mania to what he believed was Huntington chorea, later termed HD. He presented his findings at the Venezuelan Sixth Congress of Medical Science in 1955. He was met with reluctance in the local scientific community and a passive ear from government authorities. His description, written in Spanish, was not widely distributed beyond Venezuela, and its importance would have to wait until one of his students shared his observations (more than a decade later) with the HD research community and the rest of the world. CONCLUSION: The "dancing mania" of Maracaibo, because of the work of Americo Negrette, has been reclassified as Huntington disease.

Attitude to Health↗
PubMed2004

PNA Technology.

Peptide nucleic acids (PNA) are deoxyribonucleic acid (DNA) mimics with a pseudopeptide backbone. PNA is an extremely good structural mimic of DNA (or of ribonucleic acid [RNA]), and PNA oligomers are able to form very stable duplex structures with Watson-Crick complementary DNA and RNA (or PNA) oligomers, and they can also bind to targets in duplex DNA by helix invasion. Therefore, these molecules are of interest in many areas of chemistry, biology, and medicine, including drug discovery, genetic diagnostics, molecular recognition, and the origin of life. Recent progress in studies of PNA properties and applications is reviewed.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Spontaneous generation and the hygienic concern about germ dissemination].

This paper analyzes the answer given by Pasteur to those who defended the spontaneous generation theory and evaluates the impact these arguments had on the history of public hygiene. Because of that, the article emphasizes transmission of germs, rather than the origin of life, which has been quite analyzed. It also discusses the criticism Pasteur made to naturalists' arguments and tries to show that it is possible to say there is a certain continuity between the air-related concerns on the part of classic hygienists, most of which infectionists, and Pasteur's concern with germs spread in the air.

Bacteria↗
PubMedDate not supplied

[Adolpho Lutz: a biographical sketch].

This article portrays the family origins and life story of Adolpho Lutz (1855-1940) up to his transfer to the Instituto Oswaldo Cruz in 1908. His life history is used as a motif for an analysis of the institution of pasteurian and tropical medicine in Brazil. His university and postgraduate study in German-speaking Europe are examined, as are his activities as a clinician and researcher on subjects related to helminthology, parasitology, veterinary medicine and bacteriology in the interior of São Paulo state; his stay at the Molokai leprosarium in Hawaii; and the medical controversies in which he participated as head of the Bacteriological Institute of São Paulo, especially those on cholera, dysenteries, typhoid fever, malaria and yellow fever.

Brazil↗
PubMed2000

Comparative physiology of body fluid regulation in vertebrates with special reference to thirst regulation.

The origin of life took place in the ancient sea where the ionic concentration is thought to have been somewhat lower than that of the present day seas. This may partly explain why most vertebrate species have plasma ionic concentrations roughly one-third of seawater. Exceptions are primitive marine cyclostomes whose plasma is almost identical to seawater, and marine cartilaginous fishes that accumulate urea in plasma to increase osmolarity to a seawater level. The mechanisms for regulation of water and electrolyte balance should have evolved from these animals into those of more advanced ones in which plasma ions are regulated to one-third of seawater irrespective of the habitat. Although most extant terrestrial and aquatic animals maintain similar plasma osmolarity and ionic concentrations, the mechanisms of regulation differ greatly among different groups of animals according to their habitat. An outstanding difference is that while plasma Na(+) concentration is a primary factor of regulation in terrestrial mammals and birds, blood volume is most strictly regulated in aquatic teleost fishes. Consistently, while an increase in plasma osmolarity (cellular dehydration) is a major dipsogenic stimulus for birds and mammals, hypovolemia (extracellular dehydration) is a much stronger stimulus for elicitation of drinking in teleost fishes. Furthermore, fish cells in culture are tolerant to changes in environmental osmolarity compared with mammalian cells, further suggesting a secondary role of plasma osmolarity as a target of regulation in fishes. A secondary role of blood volume for body fluid regulation in birds is further assessed by the fact that volume receptors for thirst, salt gland secretion, and vasotocin secretion are localized in the extravascular, interstitial space in some species of birds. All terrestrial animals including mammals have derived from the fishes in phylogeny, during which the mechanisms for body fluid regulation underwent adaptive evolution in the course of transition from aquatic to terrestrial life. Therefore, much can be learned from comparative studies of body fluid regulation that reveals the diversity and uniformity of the mechanisms. In this review, important comparative studies that may contribute to an understanding of body fluid regulation throughout vertebrate species will be summarized.

Adaptation, Biological↗
PubMed1998

From exobiology to cosmobiology at LISA and elsewhere.

Since the emergence of Exobiology, back to the l960ties, this field drastically increased and, although differently named, is today a largely recognized scientific domain of wild interdisciplinarity. It includes not only the search for extraterrestrial living Systems, in particular by direct exploration of planetary bodies and studies of extraterrestrial materials, but also the study on the origins of life on Earth and, in connection to this field, the study of extraterrestrial organic chemistry. The exobiology programmes currently developed at LISA are related to this last aspect. They include the study of prebiotic-like chemistry in the gas and solid phases, based on laboratory simulation experiments, theoretical modeling and future in situ measurements in Titan's atmosphere and in cometary nuclei. A national program of exobiology, coordinated by LISA is under development in France, it covers many of the various aspects of Exobiology, including the study of life in extreme environments, as a reference tool for extraterrestrial life, the study of the primitive environment of the Earth, of the organic chemistry in comets and on Titan, of Mars and Europa and even of extrasolar planets as potential niches for extraterrestrial living systems, associated to the determination of the electromagnetic signatures of life. In parallel to this general program, a proposal for a large simulation chamber to be used as a national facility in particular to simulate the organic chemistry in various planetary environments, and in the interstellar medium, is under preparation. International cooperations linked to these programmes, in particular in the frame of the development of an exobiology facility on the International Space Station, would be of crucial interest.

Atmosphere↗
PubMed1994

Criteria for use of blue "Star of Life" for emergency medical services. National Highway Traffic Safety Administration. Notice.

This notice amends NHTSA's guidelines for the authorized use of the blue "Star of Life" symbols for emergency medical services. Comments received in response to an earlier notice suggested uses for this symbol that were not considered when these guidelines were first developed. These amendments are intended to provide additional flexibility to the States within the purposes for which the blue Star of Life was originally registered as a certification mark.

Emergency Medical Tags↗