A hypothesis concerning the sharp pitch discrimination observed in the sleeping cat

Résumé Une hypothèse est présentée pour expliquer la discrimination tonale précise du chat endormi. Postulats: (A) Un mécanisme de déclenchement détermine si la réponse aura lieu ou non²; et il faut qu'une quantité minime de neurones de déclenchement soit activée. (B) Le nombre de cellules activées par chaque ton est une variable aléatoire avec une distribution qui possède certaines caractéristiques.

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Supported by a Grant and Research Career Development award from USPHS.     

2-Carboxyethylgermanium sesquioxide,a synthetic organogermanium compound,as an inducer of contrasuppressor T cells

2-Carboxyethylgermanium sesquioxide (Ge-132), a synthesized organogermanium compound with immunomodulaing activities, was shown to be an inducer of anti-suppressor T cells in normal mice. The suppressor cell activity of T6S cells, a clone of burn-induced CD8⁺ IL-4-producing suppressor T cells, was clearly inhibited when a mixed lymphocyte-tumor cell reaction of the clone was conducted with splenic mononuclear cells from mice treated orally with a 100 mg/kg dose of Ge-132. The activity of anti-suppressor cells was demonstrated in spleens of mice 2 days after treatment with Ge-132 and reached its peak on day 3. The anti-suppressor cells induced by the compound were of a contrasuppressor T cell-linage, because they were characterized as CD4⁺ CD28⁺ TCR/⁺ Vicia villosa lectin-adherent T cells. These cells produced IFN- but did not produce IL-2, IL-4, IL-6 or IL-10 in their culture fluids. CD4⁺ anti-suppressor T cells induced by Ge-132 may be different from other subsets of CD4⁺ T cells because Th1 and Th2 cells generated in our laboratory did not adhere toVicia villosa lectin-coated petri dishes, and each produced specific cytokines. Th1 cells produced IFN- and IL-2 while Th2 cells produce IL-4 and IL-10 in vitro. These results suggest that Ge-132 may be useful as an inducer of contrasuppressor T cells in immunocompromised individuals bearing suppressor T cells. To eliminate suppressor T cells from immunocompromised hosts may result in improved resistance from various opportunistic infections.     

On the biogenesis of neoflavanoids: A new hypothesis

Zusammenfassung Eine neue Hypothese für die Biogenese der Neoflavanoide wird vorgeschlagen, indem dasselbe Chalkon als Zwischenstufe wie für die Flavanoide postuliert wird. Nach dieser Hypothese sollte sich nach Verabreichung von [3-¹⁴C]-Phenylalanin die Markierung an C-4 des Neoflavanoids befinden, wie es beim Calophyllolid⁶ tatsächlich der Fall ist.     

A reassessment of the use of modified Tyrode's solution as a physiological medium for suspension of isolated platelets

Résumé L'agitation constante de la solution de Tyrodes modifieé, un moyen physiologique fréquemment utilisé pour resuspendre les plaquettes isolées ou pour diluer le plasma riche en plaquettes durant le contrôle turbidimétrique de l'aggrégation, cause une augmentation rapide du pH. De ce fait, l'introduction d'un mélange de 95% O₂ à 5% CO₂ dans le compartiment d'échantillon du spectromètre réduit le pH de cette solution à son taux original.     

Genetic factors in neurotoxicology and neuropharmacology: A critical evaluation of the use of genetics as a research tool

Animals have evolved a detoxication system to enable them to survive in a hostile chemical environment in which foods contain many non-nutrient chemicals. Detoxication depends on enzymes which are often genetically polymorphic. As a result, inter-individual variation is common, and in humans several Mendelian loci have been identified. However, most variation in response is probably due to the action of several genes. Genetic variation in response to the neurotoxin MPTP and to chemically and physically-induced seizures is reviewed. In the former case, differences between pigmented and white mouse strains have been noted which are consistent with the hypothesis that humans are more sensitive than mice or rats because of the presence of melanin in human brains. However, variation in sensitivity probably also depends on other genes. In the case of audiogenic seizures, a single locus has been identified and mapped, but its relationship with seizures induced by other agents is not clear. Genetic variation in response to alcohol is also discussed. The failure of most toxicologists to consider genetic variation as a potentially confounding variable, and as a powerful research tool, is discussed critically in relation to non-repeatability of research on the neurotoxic effects of lead, and in relation to the genetic variation in MPTP, seizures, and alcohol response already noted. It seems clear that genetic methods provide a powerful research tool which is largely being ignored by toxicologists.     

Occurrence of polyploidy and multinuclearity in the differentiating liver of chick embryo

Summary Increase in nuclear size in liver has been used as an index of polyploidy. It has long been considered that the occurrence of polyploidy and multinuclearity are characteristics of mammalian liver. The present study shows the occurrence of these phenomena in the liver of birds, so these features are not confined to mammals. 3 classes of nuclear size groups have been identified. The simultaneous occurrence of polyploidy and binuclearity indicates some sort of interrelationship between them.     

A pathogenic hypothesis of malformation caused by amniocentesis

Summary The role of amniocentesis in producing fetal malformations has been investigated in the rat. Relevant uterine contractions were observed after amniocentesis. The pathogenetic mechanism of fetal malformations is discussed on the basis of the present results.This research was supported by a grant of CNR.     

A pathogenic hypothesis of malformation caused by amniocentesis.

The role of amniocentesis in producing fetal malformations has been investigated in the rat. Relevant uterine contractions were observed after amniocentesis. The pathogenetic mechanism of fetal malformations is discussed on the basis of the present results.     

Isolation of bacteria that use that use nitric oxide as a respiratory electron acceptor under anaerobiosis]

Ten bacteria of the genus Bacillus were isolated from pasteurized soils, in anaerobiosis and at 32 degrees C, on peptone broth containing 0.5% KNO2. They are Gram variable rods producing oval spores. They are oxidase positive and have catalase. They grow, in anaerobiosis, on NO-3, NO-2, N2O, and NO as respiratory electron acceptors. These compounds are reduced to N2.     

Renouvier and the method of hypothesis

Renouvier was among the first philosophers in France to break with the nineteenth-century inductivist tradition and defend the use of hypotheses in science. Earlier in the century, the humanistically-educated eclectic spiritualist philosophers who dominated French academic life had followed Reid in proscribing the use of hypotheses. Renouvier, who was educated in the sciences, took up the Comtean positivist alternative and developed it further. He began by defending hypotheses that anticipate laws governing the phenomena, but then eventually adopted a more liberal attitude towards hypotheses that postulate unobservable entities and processes as well. He also came to the realization that, from an epistemological point of view, all of empirical science is hypothetical. Renouvier used the tentative character of scientific knowledge as a premise from which to critique those who would claim scientific status for their social philosophies, and maintained a distinction between normative philosophical and empirical scientific inquiries.     

l-Isoleucine: An inducer of the feeding response in decapod crustaceans

Zusammenfassung Es wird gezeigt, dassl-Isoleucin eine starke Fressreaktion bei 6 Arten dekapoder Krebse hervorruft. Die wirksame Konzentration dieser Substanz war unter 2,3×10^–6 M/l.