Relación entre la interacción del preescolar con el personal educativo y su desarrollo psicomotor: Un estudio longitudinal chileno / Relationship between Preschool Interaction with Faculty and Psychomotor Development: A Longitudinal Chilean Study

El desarrollo psicomotor se asociaría con la calidad de las interacciones entre el niño(a) y los adultos significativos, siendo un importante predictor de su salud física y mental. El estudio analizó el desarrollo psicomotor y el cambio en la interacción de los niños(as) con el personal educativo en la sala cuna, evaluado en cuatro mediciones durante quince meses. Se estudió a 97 niños(as) entre 8 y 24 meses de edad (primera medición) con los instrumentos E.E.D.P y TEPSI y al personal educativo con CARE-INDEX. Los resultados muestran que la cooperatividad aumenta significativamente a lo largo del tiempo, presentándose diferencias por sexo. El desarrollo psicomotor no presentó cambio significativo ni está asociado con los estilos interaccionales de los niños(as).

Psychomotor development would be associated with the quality of interactions between the child and the significant adults, being an important predictor of physical and mental health. The study analyzed the psychomotor development and change in the interaction of children with the nursery's faculty, evaluating four measurements for 15 months. We studied 97 children between 8 and 24 months of age (first measurement) with the E.E.D.P and the TEPSI. Faculty was assessed with the CARE-INDEX. Results show that cooperation increases significantly over time, with sex differences. Psycho-motor development didn't change significantly and is not associated with the interactional children's styles.

Cooperative binding interaction of ethidium with allosteric DNA

The specific association of drugs with deoxyoligonucleotides, containing a B-Z junction between left-handed Z-DNA and right-handed B-DNA, was examined by fluorescence and circular dichroism (CD) technique. Ethidium was chosen for a simple DNA binding compound because it binds to right-handed DNA and hybrid B-Z forms containing a B-Z junction in a highly cooperative manner. The binding isotherms were analyzed by an allosteric model in order to describe the cooperativity of association. Binding of ethidium to the DNA that are initially in the hybrid B-Z forms showed over an order of magnitude higher affinity than other DNA which were entirely in the B-form. The conformational transitions of deoxyoligonucleotides containing a B-Z junction as a result of ethidium binding were monitored by CD and the influence of NaCl on the complex formation was also determined by the CD spectra. The singular value decomposition (SVD) analysis was used to characterize a family of CD spectra of the species in binding equilibria. The results of SVD analysis showed a strikingly complex thermodynamic equilibria of cooperative binding of drugs to the allosterically converted DNA forms. The results also showed that these DNA forms in low- and high-salt were different in the absence or presence of drug. These results demonstrate that DNA-binding-drugs can preferentially interact with specific DNA structures and that these interactions are accompanied by allosteric changes of DNA conformations.

Platelet activating factor-induced aggregation of calf platelets: apparent positive cooperativity in the kinetics and non competitive inhibition by diltiazem.

Aggregation of calf platelets by platelet activating factor was characterized by a spectrophotometric method. The aggregation kinetics of both platelet-rich plasma and purified platelets showed concave up double-reciprocal plots and linear Hill plots with h > 1 (1·7 ± 02) consistent with positive cooperativity. Comparable values of maximum rates of aggregation (R) were obtained with platelet-rich plasma (0·25 ± 0·08) and purified platelets (0·28 ± 0.18) but the half-maximal saturation concentration (S0.5) differed greatly between platelet-rich plasma (6 ± 3 nM) and purified platelets (0·28 ± 0·18 nM). An Arrhenius activation energy of 21 ± 2 kcal/mol was found for aggregation of purified platelets. Diltiazem was inhibitory with half-maximal inhibitory concentration (I0·5) of 4 M but the inhibition was not competitive. Diltiazem inhibited rates but not the extent of shape-change. The receptor-antagonist and sulphydryl reagent N-ethylmaleimide and the platelet antagonistic omega-3-fatty acid, 5,8,11,14,17-eicosa pentaenoic acid, inhibited both rates and extent of shape-change reactions and inhibited aggregation competitively (I0.5 ~ 5 μM). Eicosa pentaenoic acid at > 25 μM could abolish shape-change reactions and at 50 μM served as an activator of platelets and the activation was enhanced by aspirin (1 mM). Although N-ethylmaleimide at > 20 μM could also induce platelet activation it failed to induce aggregation and aspirin had no effect on the shape-change reactions induced by it.