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T Tordjmann

Publications and source records attributed to T Tordjmann.

22 records · Page 2Linked to original sources
PubMed1995

[Hormone-mediated calcium responses of rat and human hepatocytes. Study of multicellular systems by videomicroscopy].

OBJECTIVES AND METHODS: Activation of hepatocyte hormonal receptors leads to the mobilization of intracellular Ca2+ which is thought to be an elaborate system for encoding hormonal messages. We studied hormone-induced calcium signals in freshly isolated multicellular systems of normal rat and human hepatocytes. Calcium signals were recorded by videomicroscopy after stimulation with noradrenaline, angiotensin II, and vasopressin. RESULTS: Calcium signals were highly organized in multiplets: the different hepatocytes responded to Ca(2+)-mobilizing hormones in a sequentially ordered manner, with a first, a second (doublets) and a third (triplets) responding cells. This pattern was an intrinsic feature of the multicellular systems, and seemed to be a result of a gradual heterogeneity of the sensitivity of the different cells, to the hormones. The stimulation of the same multiplet with two different agonists and the removal of the hormone during cell responses provides some evidence for the major role of hormonal receptors in this heterogeneity. CONCLUSIONS: Hormone responses in multicellular systems of rat and human hepatocytes are highly elaborate. The density of hormonal receptors could be the major determinant of the sequential pattern of Ca2+ responses. Hormonal receptors may be gradually distributed among the different cells of the multiplets in vitro and along the porto-centrilobular axis in situ.

Angiotensin II↗
PubMed1994

Ca(2+)-mobilizing hormones induce sequentially ordered Ca2+ signals in multicellular systems of rat hepatocytes.

The development of hormone-mediated Ca2+ signals was analysed in polarized doublets, triplets and quadruplets of rat hepatocytes by video imaging of fura2 fluorescence. These multicellular models showed dilated bile canaliculi, and gap junctions were observed by using an anti-connexin-32 antibody. They also showed highly organized Ca2+ signals in response to vasopressin or noradrenaline. Surprisingly, the primary rises in intracellular Ca2+ concentration ([Ca2+]i) did not start randomly from any cell of the multiplet. It originated invariably in the same hepatocyte (first-responding cell), and then was propagated in a sequential manner to the nearest connected cells (cell 2, then 3, in triplets; cell 2, 3, then 4 in quadruplets). The sequential activation of the cells appeared to be an intrinsic property of multiplets of rat hepatocytes. (1) In the continued presence of hormones, the same sequential order was observed up to six times, i.e. at each train of oscillations occurring between the cells. (2) The order of [Ca2+]i responses was modified neither by the repeated addition of hormones nor by the hormonal dose. (3) The mechanical disruption of an intermediate cell slowed down the speed of the propagation, suggesting a role of gap junctions in the rapidity of the sequential activation of cells. (4) The same multiplet could have a different first-responding cell for vasopressin or noradrenaline, suggesting a role of the hormonal receptors in the sequentiality of cell responses. It is postulated that a functional heterogeneity of hormonal receptors, and the presence of functional gap junctions, are involved in the existence of sequentially ordered hormone-mediated [Ca2+]i rises in the multiplets of rat hepatocytes.

Animals↗
PubMed1994

[Treatment of acute colonic pseudoobstruction (Ogilvie's syndrome) by cisapride].

A case is reported of a 68-year-old woman admitted in the ICU for acute exacerbation of a chronic obstructive respiratory disease. The trachea was intubated and the lungs ventilated mechanically. She received sedation including midazolam and phenoperidine 1 mg.h-1. On the 6th day, she experienced a massive colonic dilation (caecal diameter of 10 cm at X-ray examination). A colonoscopy was performed which showed the absence of obstruction, confirmed the diagnosis of pseudo-obstruction of the colon and allowed a decompression which was inefficient. A new colonoscopic decompression was performed on the 8th day, without prolonged effect. At that time, the patient was given cisapride in her gastric tube (80 mg). This treatment restarted the bowel movements within 48 hours and the caecal diameter decreased immediately to 7 cm. Cisapride was maintained for 10 days and mechanical ventilation for 30 days. No further dilation occurred during this time and the patient was discharged from the ICU. Few cases of Ogilvie's syndrome successfully treated with cisapride have been reported in the literature. The efficacy of this agent for the treatment of Ogilvie's syndrome remains to be assessed in a controlled study.

Aged↗