Tween-20 activates and solubilizes the mitochondrial membrane-bound, calmodulin dependent NAD+ finase of Avena sativa L.

Among different treatments assayed, a mix of a nonionic detergent (5% Tween-20) with 0.5 m NaCl was found to solubilize a large part of the calmodulin-dependent NAD+ kinase bound to the inner mitochondrial membrane. It also stimulated its activity by increasing 7 times the maximal velocity. Activity stimulation was also observed with phosphatidylcholine, phosphatidylethanolamine and with reductants (HSO3 and DTT). This solubilized NAD+ kinase and the calmodulin-dependent cytosoluble isoform displayed distinct molecular masses, as well as different kinetic parameters. We propose that solubilization of membrane-bound NAD+ kinase could occur in vivo in Avena sativa and could generate a soluble isoform.

Evidence of active NADP(+) phosphatase in dormant seeds of Avena sativa L.

Freshly-harvested seeds of Avena sativa L. do not germinate when imbibed at temperatures higher than 25 degrees C. This high temperature dormancy is due to the seed coats, and to the low activities of glycolysis and the oxidative pentose phosphate pathway (OPP) in the embryo. The analysis by exclusion chromatography of soluble NADP(+) phosphatase activities of embryos revealed two isoforms: a 37 kDa isoform present in both dormant and after-ripened caryopses, and a second isoform, with an apparent molecular weight of 160 kDa, five times more active in embryos of dormant seeds than in the after-ripened ones, after 6 h of imbibition at 30 degrees C. Moreover, the activity of this 160 kDa isoform was three times less in embryos from dormant caryopses when they were grown at 10 degrees C, a permissive temperature for radicle protrusion. These results suggest a correlation between the activity of the 160 kDa NADP(+) phosphatase and the dormancy state of the caryopsis. The two isoforms differed in the pH required for optimal activity: pH 5.7 and 6.5 for the 37 kDa and the 160 kDa phosphatases, respectively. Furthermore, the 160 kDa NADP(+) phosphatase displayed a strong specificity for NADP(+), whereas the 37 kDa isoform was able to hydrolyse numerous other phosphorylated compounds.

[The use of propofol does not increase the cost of the management of patients in heart surgery with extracorporeal circulation]. / L'utilisation du propofol n'augmente pas le coût de la prise en charge des patients lors de chirurgie cardiaque avec circulation extracorporelle.

OBJECTIVES: Evaluation of the cost of propofol used for fast-track in cardiac surgery and its impact on global cost of management for anaesthesia and intensive care. STUDY DESIGN: Case-control study, prospective (1998) and retrospective (1994). PATIENTS: Twenty patients operated for cardiac surgery in 1998 and scheduled for fast-track anaesthesia. Twenty patients in 1994 matched for different criteria to the patient of 1998. METHODS: In 1998, all drugs, materials used and X-rays, biochemical assays performed were prospectively collected and their cost calculated. In 1994, similar calculations were done retrospectively. Comparison of duration of mechanical ventilation, hospitalization in intensive care and in the hospital were performed. RESULTS: Cost of anaesthesia was similar in 1994 and 1998 (2,646 FF versus 2,294 FF). Global cost of management was significantly lower in 1998 in comparison to 1994 (5,439 FF versus 8,558 FF). Duration of mechanical ventilation, hospitalization in intensive care and in the hospital were shorter in 1998 than in 1994. CONCLUSION: Despite a higher cost of propofol for anaesthesia and postoperative sedation in comparison to midazolam, the global cost of management decreased significantly in relation to a one day decrease in hospitalization in the intensive care unit.

Use of nitroglycerine to produce controlled decreases in mean arterial pressure to less than 50 mm Hg.

The cardiovascular effects of nitroglycerine (TNG) were studied in 30 patients requiring controlled hypotension for intracranial aneurysm surgery. In patients "resistant" to TNG (n = 9), sodium nitroprusside (SNP) was used to supplement the TNG. With TNG alone at a total dose of 31 mg and a mean hypotension duration of 28 min, mean arterial pressure (MAP) decreased by 43%, from 78.3 to 44.4 mm Hg as a result of decreases in cardiac index (Cl) (18%) and systemic vascular resistances (SVR) (21%). Simultaneously, a moderate increase in (Cao2 - Cvo2) (21%), and a significant increase in plasma renin activity (90%) were observed. In patients "sensitive" to TNG, the MAP decreased by 54%, Cl by 27% and SVR by 35%; HR remained stable. In patients "resistant" to TNG, the decreases in Cl and SVR were less marked: 2% and 22% respectively; the observed increase in HR was 12%. When non-toxic doses of SNP were used (less than 2 micrograms kg-1 min-1), hypotension was caused by decreased SVR (31%) and increased Cl (8%). TNG alone can be used to produce controlled decreases in MAP to around 50 mm Hg, and in patients "resistant" to TNG, SNP can be added to increase the hypotensive effect.

[Hemodynamic effects of atracurium in man]. / Effets hémodynamiques de l'atracurium chez l'homme.

Haemodynamic effects of atracurium at three doses (0.2, 0.6 and 1.2 mg . kg-1) were studied in thirty patients, anaesthetized with thiopentone (5 mg . kg-1) and fentanyl (0.2 microgram . kg-1 . min-1). No cardiovascular side-effects were observed with doses of 0.2 and 0.6 mg . kg-1. However, a 1.2 mg . kg-1 dose induced a transient but significant decrease in mean arterial pressure (-10%; p less than 0.001), maximal in the second minute, associated with an increase in heart rate (+10%; p less than 0.001) and cardiac index (+9%), and a decrease in systemic vascular resistance (-16%; p less than 0.001). The decrease in arterial pressure was constant in every patient and associated with a generalized flush in one of them. Histamine-release induced by atracurium may be one of the possible mechanisms involved in this hypotension.

Prediction of cerebral vasospasm value of fibrinogen degradation products (FDP) in the cerebro-spinal fluid (CSF) for prediction of vasospasm following subarachnoid haemorrhage due to a ruptured aneurysm.

In a new treatment regimen with antifibrinolytic drugs in patients with aneurysmal subarachnoid haemorrhages, we have systematically controlled the level of fibrinogen degradation products (FDP) in the cerebrospinal fluid (CSF). The frequency of severe vasospasm with clinical ischaemia has been compared with the patient's initial level of FDP. Fifty patients have been included in this study. (All in Hunt and Hess's grades I or II on their arrival.) Patients with a secondary deterioration unrelated to vasospasm were excluded. The FDP levels were measured in the first three days following the bleeding and we were informed of them at the end of the study. The diagnosis of severe vasospasm was confirmed by arteriography and computed tomography (CT) and it was named "severe" when accompanied with signs of clinical ischaemia. Twenty patients developed a severe vasospasm with clinical ischaemia. In these patients, the mean value of the initial FDP level was between 80 and 320 mcg/ml compared with 20 to 80 mcg/ml for those who had not developed clinical ischaemia (p = 0.0009). Furthermore, two different groups may be discriminated by their initial FDP level: FDP greater than 80 mcg/ml; n = 23, 65% severe vasospasm; FDP less than 80 mcg/ml; n = 27.8% no severe vasospasm (p less than 0.001). These results do not imply a direct role of FDP in pathophysiological mechanisms of vasospasm, but they suggest a relationship between the clot lysis and the appearance of vasospasm with clinical ischaemia. To our knowledge this is the first time that such a predictive role can be attributed to the initial FDP level in the prognosis of vasospasm.