Showing papers by "University of Geneva published in 1984"

Drawing Valid Meaning from Qualitative Data: Toward a Shared Craft

Abstract: past year has contained a good deal of impassioned argument at the paradigmatic level (Eisner, 1983; Phillips, 1983; Smith, 1983b; Tuthill & Ashton, 1983). The debate turns around the claim that epistemologies and procedures such as logical empiricism, scientism, the hypothetico-deductive method, realism, experimentalism, and instrumentalism all go together and are inherently different from-in fact, incompatible with--contrasting epistemologies and procedures of phenomenology, hermeneutics, critical theory, verstehen approaches, and artistic modes of knowing. It is argued (e.g., Norris, 1983, Smith, 1983b), that the quantitative and interpretive perspectives are irreconcilable; that claims of their complementary characteristics are unfounded; and that blending the two approaches will result in equivocal conclusions. This is a nontrivial battle, because it challenges the very foundations of the research enterprise, and particularly any given empirical study. But we are inclined to leave the battle to others, for several reasons. First, we continue to need working canons and procedures to judge the validity and usefulness of research in progress. Second, no one reasonably expects the dispute to be settled in any satisfactory way because it has come to rest on crystallized stances, each with its faithful, eager pack of recently-socialized disciples. Finally, if one looks carefully at the research actually conducted in the name of one or another epistemology, it seems that few working researchers are not blending the two perspectives.

The social development of the intellect

Abstract: Why and how do children of the human species become intelligent, at least generally, during the first years of their existence? In the first part of this paper, we would like to show how the response to this question has been formulated in terms of social psychology, but without applying social psychological investigative methods to explicate the response. As it were, the social role in cognitive development is frequently accepted as a postulate. In the second part of this chapter, we would like to show that psychological experimentation permits illustrating, if not verifying, some characteristics of the manner in which social factors intervene in cognitive development.

Asymmetric Diels-Alder and Ene Reactions in Organic Synthesis. New Synthetic Methods (48)

Abstract: Rapidly accumulating evidence shows the value of asymmetric Diels-Alder and ene reactions for the syntheses of enantiomerically pure molecules. This article presents a systematic and critical treatment of various stereoface-differentiating principles, including very recent spectacular advances. The chiral information is mainly provided by covalently bound auxiliaries, some of which are crystalline, inexpensive, and readily available from naturally occurring monoterpenes, hydroxy acids, amino acids, steroids, and sugars. Non-destructive transfer of chirality leads to the efficient creation of up to four chiral centers with predictable relative and absolute configurations. Regenerative cleavage of the auxilary group from the diastereomerically pure adducts furnishes a range of polyfunctional, optically pure building blocks. Their synthetic potential is illustrated by strategic applications to the syntheses of physiologically interesting, chiral natural products such as prostaglandins, antibiotics, terpenoids, shikimic acid, alkaloids, and kainoids.

Rapid mobilization of Ca2+ from rat insulinoma microsomes by inositol-1,4,5-trisphosphate.

Abstract: Several hormones and neurotransmitters raise the cytosolic free Ca2+ concentration by stimulating the influx of Ca2+ and/or by mobilizing stored Ca2+. However, the link between the agonist receptor on the cell surface and the organelle(s) from which Ca2+ is mobilized is unknown. One feature of the agonists that increase cytosolic Ca2+ is their rapid induction of phosphatidylinositol turnover and polyphosphoinositide hydrolysis; in some tissues this leads, within seconds, to a marked accumulation of the water-soluble products, inositol 1,4-bisphosphate ( Ins1 , 4P2 ) and inositol-1,4,5- trisphosphate ( Ins1 ,4, 5P3 ), suggesting that these might mediate Ca2+ mobilization from internal pools. Such an action of Ins1 ,4, 5P3 has recently been inferred from studies with permeabilized pancreatic acinar cells and hepatocytes. Here we show directly that Ins1 ,4, 5P3 rapidly releases Ca2+ from a microsomal fraction of rat insulinoma but not from mitochondria or secretory granules. Moreover, this response is transient and desensitizes the microsomes to subsequent Ins1 ,4, 5P3 additions. These results suggest that Ins1 ,4, 5P3 functions as a cellular messenger inducing early mobilization of Ca2+ from the endoplasmic reticulum.

Peroxidase Release Induced by Ozone in Sedum album Leaves Involvement of Ca2

Abstract: The effect of ozone was studied on the peroxidase activity from various compartments of Sedum album leaves (epidermis, intercellular fluid, residual cell material, and total cell material). The greatest increase following a 2-hour ozone exposure (0.4 microliters O3 per liter) was observed in extracellular peroxidases. Most of the main bands of peroxidase activity separated by isoelectric focusing exhibited an increase upon exposure to ozone. Incubation experiments with isolated peeled or unpeeled leaves showed that leaves from ozone-treated plants release much more peroxidases in the medium than untreated leaves. The withdrawal of Ca2+ ions reduced the level of extracellular peroxidase activity either in whole plants or in incubation experiments. This reduction and the activation obtained after addition of Ca2+ resulted from a direct requirement of Ca2+ by the enzyme and from an effect of Ca2+ on peroxidase secretion. The ionophore A23187 promoted an increase of extracellular peroxidase activity only in untreated plants. The release of peroxidases by untreated and ozone-treated leaves is considerably lowered by metabolic inhibitors (3-(3,4-dichlorophenyl)-1,1-dimethylurea and sodium azide) and by puromycin.

Protein kinase C activation of physiological processes in human neutrophils at vanishingly small cytosolic Ca2+ levels

Abstract: It has long been assumed that a rise in cytosolic free Ca2+, [Ca2+]i, is a necessary and sufficient event for the stimulation of a variety of cellular processes. The development of a technique which allows monitoring of [Ca2+]i in small intact cells has led to a critical revision of this simple postulate. We have recently shown that in neutrophils, Ca2+-ionophore-induced elevations of [Ca2+]i, quantitatively similar to those caused by chemotatic peptides, are ineffective in stimulating cell responses, which suggests that an additional signal is required for receptor-mediated activation. Here we show that subthreshold concentrations of phorbol myristate acetate (PMA) and of a Ca2+ ionophore can quantitatively mimic the effect of a physiological agonist. However, PMA at higher concentrations can trigger NADPH-oxidase activity, exocytosis and protein phosphorylation, even when [Ca2+]i is lowered 10-20 times below the normal resting level. These results strongly suggest that activation of protein kinase C is sufficient, by itself, to induce NADPH-oxidase activation and exocytosis of secondary granules in neutrophils.

The Deiodination of the Iodothyronines and of Their Derivatives in Man

Abstract: THYROIDAL secretion is the only source of thyroxine (T4) in the human systemic circulation, and in euthyroid man, T4 is the main secretory product of the gland. The metabolic fate of the hormone once thyroidal secretion has occurred is complex and involves deiodination, deamination and decarboxylation of the amino acid side chain, and esterification of the phenolic hydroxyl group with glucuronic or sulfuric acid. These pathways are not to be considered as mutually exclusive, but are interrelated in an exceedingly complex manner. Deiodination of T4 is the most important degradative pathway and accounts for up to 85% of the disposal of the hormone (1–3). At least two major mechanisms exist within the peripheral tissues by which the iodine atoms may be removed from the molecule. Of these, monodeiodination is quantitatively the most important pathway and has been subjected to the most intensive investigation.

Camphor‐Derived N‐Acryloyl and N‐Crotonoyl Sultams: Practical Activated Dienophiles in Asymmetric Diels‐alder Reactions. Preliminary Communication

Abstract: Starting from (+)-camphor-10-sulfonyl chloride (5), the crystalline sultam 8 was easily prepared. Lewis-acid-promoted Diels-Alder additions of the crystalline N-acry-loyl and N-crotonoyl derivatives 9 and 10, respectively, to cyclopentadiene and 1,3-butadiene at −130 to −78° furnished adducts 11, 12 and 17 with high chiral efficiency. Crystallization of the adducts and nondestructive removal of 8 gave either alcohols 13, 14 and 18 ir acid 19 in 99% enantiomeric purity. The sense of induction was reversed on using the enantiomer of 8 as the auxiliary. The structure of 10 was established by X-ray diffraction analysis.

Chlamydomonas reinhardii gene for the 32 000 mol. wt. protein of photosystem II contains four large introns and is located entirely within the chloroplast inverted repeat.

Abstract: The chloroplast psbA gene from the green unicellular alga Chlamydomonas reinhardii has been localized, cloned and sequenced. This gene codes for the rapidly-labeled 32-kd protein of photosystem II, also identified as as herbicide-binding protein. Unlike psbA in higher plants which is found in the large single copy region of the chloroplast genome and is uninterrupted, psbA in C. reinhardii is located entirely within the inverted repeat, hence present in two identical copies per circular chloroplast genome, and contains four large introns. These introns range from 1.1 to 1.8 kb in size and fall into the category of Group I introns. Two of the introns contain open reading frames which are in-frame with the preceding exon sequences. We present the nucleotide sequence for the C. reinhardii psbA 5'-and 3' -flanking sequences, the coding region contained in five exons and the deduced amino acid sequence. The algal gene codes for a protein of 352 amino acid residues which is 95% homologous, excluding the last eight amino acid residues, with the higher plant protein.

The Cross-Cultural Study of Intelligence: Piaget and the Baoule

Abstract: There are two aspects of Piaget's theory that can be at least partly distinguished: (1) the stage theory, or the development of particular concepts through a series of hierarchical stages; (2) the metatheory, or the interactionist model of adaptation (assimilation and accommodation) that explains the mechanisms of cognitive development. Most cross-cultural research has been based on the first of these aspects, using and adapting “Piagetian tasks” in various conceptual areas. Some findings of this line of enquiry, and the methodological problems encountered, are briefly reviewed. It is argued that no specific task, nor a combination of them, can be taken to measure a general cognitive level; the tasks measure the attainment of particular concepts rather than “intelligence”. New evidence is presented on the reliability and validity of Piagetian tasks used in a cross-cultural setting. In the second model, intelligence is broadly defined as adaptation to the environment; in this conception it would b...

High-pressure valence instability and T c maximum in superconducting CeCu 2 Si 2

Abstract: The high-pressure electrical resistivity of the Kondo compound ${\mathrm{CeCu}}_{2}$${\mathrm{Si}}_{2}$ was investigated down to the subkelvin temperature range. The main result is the occurrence of a valence transition associated with a steep increase of the superconducting critical temperature ${T}_{c}$ to about 2 K near 25 kbar. In the intermediate-valence phase, $\frac{\ensuremath{\partial}{T}_{c}}{\ensuremath{\partial}P}$ is negative, and no evidence for superconductivity is found above 1.2 K for $Pg100$ kbar. At pressure of the order of 200 kbar, the $\ensuremath{\rho}(T)$ curves between 0 and 300 K are similar to those for ${\mathrm{LaCu}}_{2}$${\mathrm{Si}}_{2}$ at ambient pressure. The preceding results are discussed in terms of a two-component ($sd+f$) picture.

Sequence homology between the 32K dalton and the D2 chloroplast membrane polypeptides of Chlamydomonas reinhardii

Abstract: The region of the chloroplast genome of Chlamydomonas reinhardii containing the gene of the thylakoid polypeptide D2 (psbD) has been sequenced. A unique open reading frame of 350 codons exists in this region. Because the first ATG is followed 11 codons downstream by a second one, the D2 polypeptide consists of either 339 or 350 amino acids. Comparison of the sequences of D2 and the 32K dalton polypeptides, both of which are associated with photosystem II, reveals partial homology. Although, the overall homology of these two polypeptides is only 27%, they contain several related regions and their hydropathic profiles are strikingly similar. These data suggest that the two polypeptides may have related functions and/or that their genes may have originated from a common ancestor. Alternatively, convergent evolution of these polypeptides may be due to structural constraints in the thylakoid membrane. Limited sequence homology is also observed between the D2 polypeptide and some of the subunits of the reaction centers of photosynthetic bacteria.

La Crosse virions contain a primer-stimulated RNA polymerase and a methylated cap-dependent endonuclease.

Abstract: Purified La Crosse virions in vitro were found to transcribe their negative polarity (-)RNA genomes. This polymerase activity was stimulated by oligonucleotides such as (A)nG, cap analogs such as m7GpppAm, and natural mRNAs such as alfalfa mosaic virus RNA 4. For (A)nG- and alfalfa mosaic virus RNA 4-stimulated reactions, evidence is presented that these RNAs stimulate activity by acting as primers for viral transcription. The cap analogs appear to stimulate activity via an alternative mechanism. Purified La Crosse virions were also found to contain an endonuclease which specifically cleaves alfalfa mosaic virus RNA 4 when this RNA contains a methylated cap group.

Herbicide resistance in Chlamydomonas reinhardtii results from a mutation in the chloroplast gene for the 32-kilodalton protein of photosystem II.

Abstract: We report the isolation and characterization of a uniparental mutant of Chlamydomonas reinhardtii that is resistant to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine). Such herbicides inhibit photosynthesis by preventing transfer of electrons in photosystem II from the primary stable electron acceptor Q to the secondary stable electron acceptor complex B, which is thought to contain a protein of 32 kDa and a bound quinone. It has been proposed that herbicide binding to the 32-kDa protein alters the B complex so that electron transfer from Q is prohibited. Both whole and broken-cell preparations of the mutant alga show a resistance to the effects of herbicide on electron transfer from Q to B, as measured by fluorescence-induction kinetics. In the absence of herbicide, mutant cells exhibit a slower rate of Q to B electron transfer than do wild-type cells. The 32-kDa protein from wild-type cells, but not mutant cells, binds azido[14C]atrazine at 0.1 μM. We have isolated psbA, the chloroplast gene for the 32-kDa protein, from both wild-type and herbicide-resistant algae and sequenced the coding regions of the gene that are contained in five exons. The only difference between the exon nucleotide sequences of the wild-type and mutant psbA is a single T-A to G-C transversion. This mutation results in a predicted amino acid change of serine in the wild-type protein to alanine in the mutant. We suggest that this alteration in the 32-kDa protein is the molecular basis for herbicide resistance in the C. reinhardtii mutant.

Observation of Magnetic-Field-Induced Superconductivity

Abstract: A new superconducting state induced by an external magnetic field has been observed in the pseudoternary Eu-Sn molybdenum chalcogenides for different Eu concentrations. This phenomenon is explained in terms of the Jaccarino-Peter compensation effect which accounts correctly for the shape of the H c2-T phase diagram.

Characterization of La Crosse virus small-genome transcripts.

Abstract: With restriction fragments from DNA clones of the La Crosse virus S genome segment, the 3' end of the S mRNA was located by S1 nuclease mapping near a polyuridine tract, approximately 100 nucleotides, from the end of the S genome. Genome replication in La Crosse virus-infected cells was abolished by the drug cycloheximide, similar to other negative-strand RNA viruses. However, the synthesis of S mRNA could not be detected in cells pretreated with cycloheximide, suggesting that ongoing protein synthesis is required for La Crosse virus genome transcription and replication. Primer extension experiments in the presence of chain-terminating nucleoside triphosphates demonstrated that the 5' end of the La Crosse virus S mRNA begins 10 to 14 nucleotides before the 3' end of the S genome segment, suggesting that the La Crosse virus S mRNA is initiated on a host primer. A hypothesis consistent with these unexpected findings is presented.

The expression of heat shock genes during normal development in Drosophila melanogaster (heat shock/abundant transcripts/developmental regulation)

Abstract: Drosophila melanogaster cells and tissues respond to heat shock by dramatically altering their pattern of transcription and translation, leading to the rapid synthesis of a small number of polypeptides, the heat shock proteins (hsps). By using cloned hsp DNA we have detected sequences complementary to heat shock genes in RNA prepared from non-heat-shocked animals of different developmental stages. Hsp 83 mRNA is present at high levels in all stages examined. Hsp 68 and 70 mRNAs are present at very low levels in most stages and at slightly higher concentration in pupae. Hsp 26 and 27 mRNAs are detected in embryos. Hsp 23, 26 and 27 mRNA are barely detectable in early third instar larvae but are major components of late third instar and early pupal RNA. Hsp 22 mRNA is also detected in early pupae. Later in development the levels of the small hsp mRNAs decrease but a further peak in abundance of hsp 26 and 27 mRNAs is found in mature adult females.

Asymmetrische Diels‐Alder‐ und En‐Reaktionen in der Organischen Synthese

Abstract: Eine rasch wachsende Fulle von Ergebnissen bezeugt die Leistungsfahigkeit asymmetrischer Diels-Alder- und En-Reaktionen zur Synthese enantiomerenreiner Verbindungen. Der vorliegende Aufsatz erfast systematisch und kritisch eine Auswahl stereoseitendifferenzierender Prinzipien unter Einbeziehung neuester, spektakularer Fortschritte. Die „chirale Information” entstammt im allgemeinen kovalent gebundenen Hilfsgruppen; einige Hilfsstoffe sind kristallin, preiswert und bequem aus naturlichen Quellen (Monoterpenen, Hydroxysauren, Aminosauren, Steroiden und Zuckern) zuganglich. Durch nicht-destruktive Chiralitatsubertragung entstehen bis zu vier Asymmetriezentren mit voraussagbarer relativer und absoluter Konfiguration. Abspaltung der Hilfsgruppe (teils unter effizienter Ruckgewinnung des Hilfsstoffs) von den diastereomerenreinen Addukten ergibt eine Reihe polyfunktioneller, enantiomerenreiner Synthesebausteine. Ihr Potential zeigt sich bei Synthesen von physiologisch interessanten chiralen Naturstoffen wie Prostaglandinen, Antibiotica, Terpenoiden, Shikimisaure und α-Allokaininsaure.