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PubMedDate not supplied

Quality-of-life measurements: origin and pathogenesis.

Despite extensive growth in recent years, the field of "quality-of-life" appraisal still evokes debate about basic perception of the concept and is accompanied by a plethora of indexes for measurement. One prime reason for the problems is that the measurements have been transferred from two separate sources - medical health status indexes and social-science population indexes - neither of which was designed for appraising the particular personal distinctions of the way people feel about their own quality of life. When regulatory and commercial incentives were offered for measuring patients' quality of life, it became appraised with the indexes available from the medical and psychosocial sources, even though neither set of indexes was specifically intended for that purpose. They are not developed from the basic principle that a person's "quality of life" is a state of mind, not a state of health, which is uniquely perceived by that person, and which will not be appropriately appraised unless the most cogent personal components are allowed suitable expressions. An approach that lets patients state their own opinions directly can offer the "face validity" or "common sense" that now seems absent from the generally applied measurements.

Humans↗
PubMed2005

Stereoselective differentiation in the Salt-induced Peptide Formation reaction and its relevance for the origin of life.

All living organisms on earth are almost totally made up of biomolecules of only one chiral form. For example, proteins are built almost exclusively of L-amino acids, and sugars are composed of D-saccharides, a fact that is usually referred to as biohomochirality. Its origin is the center of numerous investigations and theories but is not really elucidated yet. The results of experimental investigations of peptide formation in a prebiotically relevant scenario, as described in this paper, give indications on a possible pathway for the synthesis of homochiral L-peptides in the course of the Salt-induced Peptide Formation (SIPF) reaction.

Amino Acids↗
PubMed2006

Experimentally tracing the key steps in the origin of life: The aromatic world.

Life is generally believed to emerge on Earth, to be at least functionally similar to life as we know it today, and to be much simpler than modern life. Although minimal life is notoriously difficult to define, a molecular system can be considered alive if it turns resources into building blocks, replicates, and evolves. Primitive life may have consisted of a compartmentalized genetic system coupled with an energy-harvesting mechanism. How prebiotic building blocks self-assemble and transform themselves into a minimal living system can be broken into two questions: (1) How can prebiotic building blocks form containers, metabolic networks, and informational polymers? (2) How can these three components cooperatively organize to form a protocell that satisfies the minimal requirements for a living system? The functional integration of these components is a difficult puzzle that requires cooperation among all the aspects of protocell assembly: starting material, reaction mechanisms, thermodynamics, and the integration of the inheritance, metabolism, and container functionalities. Protocells may have been self-assembled from components different from those used in modern biochemistry. We propose that assemblies based on aromatic hydrocarbons may have been the most abundant flexible and stable organic materials on the primitive Earth and discuss their possible integration into a minimal life form. In this paper we attempt to combine current knowledge of the composition of prebiotic organic material of extraterrestrial and terrestrial origin, and put these in the context of possible prebiotic scenarios. We also describe laboratory experiments that might help clarify the transition from nonliving to living matter using aromatic material. This paper presents an interdisciplinary approach to interface state of the art knowledge in astrochemistry, prebiotic chemistry, and artificial life research.

Hydrocarbons, Aromatic↗
PubMed1975

Origin of life: clues from relations between chemical compositions of living organisms and natural environments.

When elemental enrichment factors in living organisms are plotted against the ionic potential of the elements, a strikingly similar pattern is found for different groups of organisms; the pattern is also similar, in its general features, to that found in seawater. These relationships support the idea that life began in a water-rich environment interfacing with the primitive atmosphere of the earth.

Animals↗
PubMed1981

Origin of life between Scylla and Charybdis.

The "package model" discussed here is concerned with the preservation of genetic information by primordial compartments. Each viable "package" encloses a complete set of unlinked genes in varying numbers of copies. Due to stochastic distribution and error-prone replication two potent perils endanger the informational integrity of packages: fluctuation and mutation. A computer simulation was used to quantify the effects of fluctuation, mutation, and package death by accident. Assuming reasonable rates for these parameters it is suggested that life started out with compartments containing not more than 3 different genes.

Biological Evolution↗
PubMed2006

Photocatalysis and the origin of life: synthesis of nucleoside bases from formamide on TiO2(001) single surfaces.

We report the conversion of a large fraction of formamide (NH(2)CHO) to high-molecular-weight compounds attributed to nucleoside bases on the surface of a TiO(2) (001) single crystal in ultra-high vacuum conditions. If true, we present previously unreported evidence for making biologically relevant molecules from a C1 compound on any single crystal surface in high vacuum and in dry conditions. An UV light of 3.2 eV was necessary to make the reaction. This UV light excites the semiconductor surface but not directly the adsorbed formamide molecules or the reaction products. There thus is no need to use high energy in the form of photons or electrical discharge to make the carbon-carbon and carbon-nitrogen bonds necessary for life. Consequently, the reaction products may accumulate with time and may not be subject to decomposition by the excitation source. The formation of these molecules, by surface reaction of formamide, is proof that some minerals in the form of oxide semiconductors are active materials for making high-molecular-weight organic molecules that may have acted as precursors for biological compounds required for life in the universe.

Carbon↗