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C Mathis

Publications and source records attributed to C Mathis.

At least 73 records · Page 4Linked to original sources
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Influence of jejunal nutrients on transpyloric flow and pyloric resistance in pigs.

The effects of small intestinal infusion of nutrients on the transpyloric flow and pyloric resistance were evaluated in anaesthetized pigs. Saline versus isocaloric solutions of dextrose, triglycerides and casein were infused into a jejunal loop during saline gastric loading. Antropyloroduodenal pressures were measured with a sleeve/side-hole manometric assembly and the transpyloric flow with an electromagnetic flowmeter probe. Fundic pressure was maintained constant. Although the overall gastric emptying rate was not affected by nutrients, the stroke volume of the transpyloric flow pulses was significantly increased as a consequence of larger peak flow (dextrose) or longer duration of flow pulses (triglycerides and casein). Pyloric resistance was reduced by all nutrients owing to a change in the temporal relationship between the onset of pyloric pressure events and flow pulses so that flow pulses occurred after pyloric pressure events. In conclusion, under controlled fundic pressure, nutrient infusions decrease pyloric resistance.

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[Role of neuroexcitatory amino acids in memory processes. Study with gamma-L-glutamyl-L-aspartic acid].

Convergent data demonstrate that excitatory amino acid systems (glutamate and aspartate) participate in synaptic plasticity of the central nervous system. Their action is mediated by at least three subclasses of receptors which have been characterized on the basis of their selective affinity to N-methyl-D-aspartate (NMDA), quisqualate and kainate. NMDA receptors appear to be directly involved in the induction of long-term potentiation (LTP) at the hippocampal level, and quisqualate/kainate receptors in the expression of LTP. This suggests that excitatory amino acid systems may have an important role in learning and memory. However, how these systems interfere with memory processes remains largely unknown. We have isolated a pseudopeptide, gamma-L-glutamyl-L-aspartate (gamma-LGLA) (Ungerer et al., 1988), which has the pharmacological properties of a competitive antagonist at NMDA receptors as evidenced by biochemical studies and by the fact that gamma-LGLA selectively blocks the clonico-tonic seizures induced by NMDA, while having no significant action against seizures induced by kainate or quisqualate. Elsewhere, gamma-LGLA is devoid of toxicity at the doses used. Behavioral effects of gamma-LGLA were first studied in a Y-maze avoidance learning task. Animals had to leave the start alley within 5 sec. (temporal component) and to choose the left alley of the maze (spatial component) to avoid footshock. They underwent one trial every minute and were trained to a criterion of 7 correct out of 8 consecutive trials. Retention was tested either 1 h, 3 h, 6h, 24 h, 7 days or 21 days after acquisition.(ABSTRACT TRUNCATED AT 250 WORDS)

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