Effect of age on the comparability of bispectral and state entropy indices during the maintenance of propofol-sufentanil anaesthesia.

BACKGROUND: Manufacturers recommend maintaining anaesthesia at a bispectral index (BIS) or state entropy (SE) index value between 40 and 60. METHODS: We prospectively studied 102 patients receiving propofol-sufentanil anaesthesia administered by anaesthetists blinded to these indices. The main endpoint was crude agreement (P(0)), defined as the proportion of agreement between BIS and SE index among three categories: <40, between 40 and 60, and >60. Discrepancies in recommendation (DR) were also considered. A DR is type 1 if BIS or SE is <40, while the other is simultaneously >60. A DR is type 2 when BIS and SE index values are on different sides of a threshold (40 or 60) with three subtypes according to the magnitude of their difference. A linear multiple regression was performed to identify covariates that are independently associated with P(0). RESULTS: In total, 12 147 pairs of values were studied. P(0) was 59.9 (24.5%) [mean (sd)]. Thirty-three patients presented more than 50% discordant pairs and only seven patients presented more than 95% concordant pairs. Type 1 DR occurred in only 1.1% of all the pairs. The median (inter-quartile range) number of type 2 DR varied from 5 (3-8) to 2 (1-3) according to the degree of difference. Multivariate analysis showed that age (P=0.0004) and electrode position (P=0.0084) were independently associated with P(0). An increase in the age of 10 yr decreases P(0) by 5%. CONCLUSIONS: The agreement between BIS and SE indices is moderate and deteriorates as patients' age increases. This study cannot determine which index is best adapted for elderly patients. Additional work comparing both indices with raw EEG traces is warranted.

Does an educational strategy based on systematic preoperative assessment of simplified Apfel's score decrease postoperative nausea and vomiting?

BACKGROUND AND OBJECTIVE: Postoperative nausea and vomiting (PONV) is a frequent and unpleasant side effect occurring after anaesthesia and surgery. In the present study, we hypothesized that an educational strategy based on systematic preoperative assessment of the simplified Apfel's score decreased the incidence of PONV in a population of adult surgical patients. METHODS: All consecutive patients admitted in the postanaesthesia care unit (PACU) for elective surgery under general anaesthesia were included and PONV occurring in the PACU recorded. An educational strategy consisting in printing the items allowing calculation of the simplified Apfel's score on the records of the preanaesthetic visit, and encouraging anaesthetists to measure and record it was set up. Meetings dedicated to PONV prevention by emphasis on the current guidelines were regularly organized. The primary endpoint was the incidence of PONV occurring in the PACU. RESULTS: One hundred and ninety-one patients were included during the control period (08/01/07 to 28/02/07) and 193 after the educational strategy (01/03/07 to 30/04/07). The incidence of PONV was decreased in the second period from 19.37% to 11.4% (p=0.0340). The rate of administration of intraoperative prophylactic anti-emetics in high-risk groups increased from 36.4% to 52.8% (p=0.049). The prescription rate of anti-emetic prophylaxis correlated with the PONV risk derived from the simplified Apfel's score in the second period of the study (p=0.1415 before, vs. p=0.0005 after). CONCLUSION: An educational strategy based on systematic preoperative measurement and recording of the simplified Apfel's score is efficient to decrease markedly the incidence of PONV in a population of adult surgical patients.

Interest of BIS monitoring to guide propofol infusion during the anhepatic phase of orthotopic liver transplantation.

OBJECTIVE: The anhepatic phase of orthotopic liver transplantation (OLT) is associated with significant changes in pharmacokinetics. The aim of this study was to compare the influence of this phase on propofol target concentrations during BIS guided target controlled infusion (TCI). STUDY DESIGN: Prospective study. PATIENTS AND METHODS: Eight patients aged 25 to 65 years, Child-Pugh status A-B scheduled for OLT were prospectively included. Anesthesia was performed using TCI of propofol (Diprifusor, Marsh pharmacokinetic model), sufentanil and cisatracurium. Propofol target concentration was adjusted to maintain BIS values between 40 and 50. RESULTS: To maintain stable BIS values, propofol target concentrations should be decreased during the anhepatic phase versus the dissection one (2.0 microg/ml+/-0.8 versus 3.0 microg/ml+/-0.9, p<0.0001). CONCLUSION: BIS could be useful to titrate propofol infusion during the anhepatic phase of OLT.

Effects of the knee-chest position on cardiac index and propofol requirements during bispectral index (BIS)-guided spine surgery.

INTRODUCTION: The knee-chest (KC) position is often used for spine surgery. It is considered to promote significant changes in venous return and cardiac output. However, the magnitude of these changes and their consequences on intraoperative haemodynamics and anaesthetic requirements remain to be determined. The goal of the present study was to determine the changes in cardiac index and propofol requirements of patients undergoing spine surgery in the KC position. METHODS: Twenty ASA 1-3 patients scheduled for elective spine surgery were included in the study. A radial artery catheter and an oesophageal Doppler probe were properly positioned after induction of anaesthesia. Anaesthesia consisted of bispectral index (BIS)-guided, plasma target-controlled, propofol-remifentanil anaesthesia. After positioning the patient KC, remifentanil target concentration was maintained throughout the case as in the supine position whilst propofol target concentration was adjusted to maintain BIS values between 40 and 50. Cardiac index, stroke volume, heart rate, end-tidal CO(2) (ETCO(2)), mean arterial pressure, peak and plateau airway pressures, BIS values and plasma target concentrations of propofol and remifentanil were compared 15 min after induction of anaesthesia (in the supine position) and 15 min after placing the patients KC. Data are expressed as mean+/-S.D. except for DeltaPP expressed as a number of patients with DeltaPP greater than 13%. RESULTS: Cardiac index, stroke volume, mean arterial pressure and propofol target concentration were significantly decreased from supine to KC position: 2.6+/-0.03 to 1.7+/-0.04 l/min/m(2), p<0.0001; 68+/-1.2 to 45+/-1 ml, p<0.0001; 83+/-1.2 to 76+/-1.4 mmHg, p<0.0001 and 3+/-0.06 to 2+/-0.05 microg/ml, p<0.0001, respectively. The number of patients with DeltaPP greater than 13% was zero in the supine position and 18 (90%) in the KC position (p<0.0001). CONCLUSION: Placing surgical patients in the KC position during BIS guided anaesthesia was associated with marked decrease in cardiac index and propofol requirements. These results suggest that monitoring intraoperative cardiac index via an oesophageal Doppler and depth of anaesthesia with the BIS may be useful in patients undergoing spine surgery in the KC position.

The APC is dispensable for first meiotic anaphase in Xenopus oocytes.

Here we show that segregation of homologous chromosomes and that of sister chromatids are differentially regulated in Xenopus and possibly in other higher eukaryotes. Upon hormonal stimulation, Xenopus oocytes microinjected with antibodies against the anaphase-promoting complex (APC) activator Fizzy or the APC core subunit Cdc27, or with the checkpoint protein Mad2, a destruction-box peptide or methylated ubiquitin, readily progress through the first meiotic cell cycle and arrest at second meiotic metaphase. However, they fail to segregate sister chromatids and remain arrested at second meiotic metaphase when electrically stimulated or when treated with ionophore A34187, two treatments that mimic fertilization and readily induce chromatid segregation in control oocytes. Thus, APC is required for second meiotic anaphase but not for first meiotic anaphase.

The polo-like kinase Plx1 prevents premature inactivation of the APC(Fizzy)-dependent pathway in the early Xenopus cell cycle.

Members of the polo-like family of protein kinases have been involved in the control of APC (anaphase-promoting complex) during the cell cycle, yet how they activate APC is not understood in any detail. In Xenopus oocytes, Ca2+-dependent degradation of cyclin B associated with release from arrest at second meiotic metaphase was demonstrated to require the polo-like kinase Plx1. The aim of the present study was to examine, beyond Ca2+-dependent resumption of meiosis, the possible role of Plx1 in the control of cyclin degradation during the early mitotic cell cycle. Plx1 was found to be dispensable for MPF to turn on the cyclin degradation machinery. However, it is required to prevent premature inactivation of the APC-dependent proteolytic pathway. Microcystin suppresses the requirement for Plx1 in both Ca2+-dependent exit from meiosis, associated with degradation of both cyclin B and A downstream of CaMK2 activation, and prevention of premature APC(Fizzy) inactivation in the early mitotic cell cycle. These results are consistent with the view that Plx1 antagonizes an unidentified microcystin-sensitive phosphatase that inactivates APC(Fizzy).

Lactate uptake by skeletal muscle sarcolemmal vesicles decreases after 4 wk of hindlimb unweighting in rats.

We investigated the effects of 4 wk of hypodynamia on the rate of lactate transport in skeletal muscle sarcolemmal vesicles from control and hindlimb-suspended rats. Characterization of the sarcolemmal preparations was achieved with a marker enzyme (K+-p-nitrophenylphosphatase) and measurement of 1 mM [U-14C]lactate transport activity under zero-trans conditions with or without a pH gradient or the transport inhibitor alpha-hydroxycinnamate. Preparations from the two groups were not significantly different concerning yield and purification. Based on these results, we used this model to analyze the lactate transport activity after hypodynamia by tail suspension. Hindlimb suspension caused a shift from slow to fast myosin heavy chain isoforms in soleus muscles with a 40% decrease in the citrate synthase activity (from 35.3 +/- 3.7 to 21.4 +/- 2.1 mu mol x g-1 x min-1; P < 0.05). Lactate (1 mM) uptake in vesicles from the two groups was a function of time, and the rate after hindlimb suspension was significantly decreased in the suspended compared with the control group (2.25 +/- 0.44 and 3.50 +/- 0.26 nmol x min-1 x mg protein-1, respectively; P < 0.05). These differences were not observed for a higher lactate concentration (50 mM). These results suggest that the level of physical activity plays a role in the regulation of sarcolemmal lactate transport activity implicated in the exchanges of lactate between producing and utilizing cells, organs, and tissues, which are major ways of carbohydrate energy distribution in humans and others species.

Onset of chromosome segregation at the metaphase to anaphase transition of the cell cycle.

Chromosome segregation is one of the most important acts in the life of the cell. Unequal inheritance of chromosomes (aneuploidy) is a cause of a number of disorders, particularly in humans, even though eukaryotic cells can arrest or delay the transition from metaphase to anaphase if an event critical to the completion of metaphase is impaired. In this report, we review recent advances in our knowledge of how the complex process of chromosome segregation is coupled with cell cycle progression, and starts at onset of anaphase with sister chromatids separation of the replicated chromosomes.

Phorbol myristate acetate inhibits phosphoinositol lipid-specific phospholipase C activity via protein kinase C activation in conditions inducing differentiation in HL-60 cells.

We have studied, in streptolysin O-permeabilized HL-60 cells and in HL-60 membrane preparations, the effects of phorbol 12-myristate 13-acetate (PMA) on polyphosphoinositide-specific phospholipase C (PLC) activity and on terminal differentiation towards macrophagic-like cells. We showed that terminal differentiation was induced when differentiating concentrations of the drug were present for only 1-2 h in the culture medium. Conditions inducing differentiation also inhibited PLC activity for a long lasting period (at least 5 h). When terminal differentiation affected only part of the cell population, inhibition of phospholipase C activity was found to be less marked and reversible over the period studied. Moreover in experiments done in an HL-60 clone resistant to PMA, no inhibition of PLC activity was provoked by this tumour promotor. In order to study the involvement of protein kinase C in this process, we measured modifications of PLC activity by PMA in the presence of two different protein kinase C inhibitors, staurosporine and H-7. They both prevented the inhibition of PLC activity by PMA indicating that this inhibition is likely to be related to the effect of PMA on protein kinase C activity. This was also confirmed by the fact that active protein kinase C, by itself, was able to decrease PLC activity when added to membrane preparations or to streptolysin O-permeabilized control HL-60 cells. These results indicate that PMA acts in inhibiting phospholipase C activity through its effect on protein kinase C activation and/or on protein kinase C translocation to the plasma membrane and that terminal differentiation, might be related to changes in both protein kinase C and PLC activities.

The differentiating agent, retinoic acid, causes an early inhibition of inositol lipid-specific phospholipase C activity in HL-60 cells.

Retinoic acid, a derivative of vitamin A, is shown to inhibit the levels of inositol phosphates and diacylglycerol by 25-30% when added to intact HL-60 cells at concentrations which induce differentiation. The onset of inhibition occurs after 10 min and reaches a maximum at 45 min. To study the mechanism and the site of action of retinoic acid, the activity of the phosphatidylinositol bisphosphate-specific phospholipase C was studied in cells permeabilized with streptolysin O and in membrane preparations. Phospholipase C activity was stimulated either via the guanine nucleotide regulatory protein (G-protein) or directly by Ca2+. Retinoic acid treatment, in a time- and concentration-dependent manner, led to a decrease in phospholipase C activity when stimulated with either GTP gamma S or NaF, both of which activate the enzyme via the G-protein. By contrast, it had no effect on the enzyme activity when stimulated with Ca2+ alone. This indicates that retinoic acid interferes with the coupling of the G-protein and phospholipase C. A relationship between the inhibition of phospholipase C activity and the induction of differentiation by retinoic acid was investigated. Only a small inhibition of GTP gamma S-stimulated phospholipase C activity was observed when an analogue of retinoic acid, etretine or Ro10-1670, with low differentiating activity, was used. Moreover, no inhibition of the GTP gamma S-stimulated phospholipase C activity was observed in an HL-60 sub-line resistant to retinoic acid. These results suggest that phospholipase C inhibition is an important step in the induction of differentiation.

The glutamate receptor of the Qp-type activates protein kinase C and is regulated by protein kinase C.

In striatal neurons in primary culture quisqualate potently stimulated the formation of inositol phosphates via a metabotropic receptor we recently termed Qp in order to distinguish it from the classical ionotropic quisqualate receptor termed Qi. Here we show that 10 microM of quisqualate activated in a rapid and transient manner protein kinase C as assessed by its translocation from the cytosolic to the membrane fraction. As 10 microM alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), the Qi specific agonist, was without effect, this translocation was most probably mediated by the Qp receptor. Phorbol 12,13-dibutyrate blocked in a dose-dependent manner the Qp receptor-induced inositol phosphate formation (IC50 = 2 +/- 0.4 nM). The inactive ester 4 alpha-phorbol-12,13-didecanoate was without effect. Very low concentrations of staurosporine completely reversed the phorbol 12,13-dibutyrate-induced blockade (IC50 = 2.2 +/- 1.3 nM). It can therefore be concluded that the Qp receptor is able to activate protein kinase C and that the activity of this metabotropic receptor is regulated by protein kinase C.

Effects of fluorescent derivatives of TPA on HL60 cells: dissociation between the differentiation-induced and protein kinase C activity.

The four fluorescent derivatives of TPA--dansylaza-TPA, NBDaza-TPA, and (N)- and (P)-dansylamino-TPA--were synthesized and examined for their ability to induce differentiation in human promyelocytic leukemic HL60 cells. At a concentration of 20 nM, all the derivatives inhibited proliferation and induced 60-80% of the cells to differentiate into macrophage-like cells. Removal of dansylaza-TPA from the medium after 5 h did not arrest adherence or the expression of nonspecific esterase activity. However, upon removal of any of the other three compounds after 5 h, HL60 cells became nonadherent and expressed low nonspecific esterase activity after additional culture. To investigate the relationship between protein kinase C (PKC) activation and cell maturation, PKC activity and translocation were measured after 0.5, 5, 24, and 48 h of treatment with each compound. Cells induced to differentiate by dansylaza-TPA or (N)- or (P)-dansylamino-TPA exhibited enhanced PKC activity, 50-80% of which was located in the particulate fraction. In cells that differentiated with NBDaza-TPA, 65-70% of PKC activity remained in the cytosol. After removal of the TPA derivatives, all cells exhibited PKC activity in the cytosol. These results indicate that the fluorescent derivatives are as potent as TPA in inducing HL60 cell differentiation. However, in the case of NBDaza-TPA and (N)- or (P)-dansylamino-TPA, their continuous presence in the culture medium was required for the recruitment of cells to differentiate. Consequently, it is suggested that activation and translocation of PKC are among the early biochemical events that trigger HL60 cell differentiation. Nevertheless, these two events alone are not sufficient to induce differentiation.

The DNA synthesis of leukemic (L2C) guinea pig B lymphocytes involves a permanent activation of protein kinase C without corresponding phosphoinositide hydrolysis.

L2C B lymphocytes have a constant high DNA synthesis due to their continuous proliferative state. The addition of polymyxin B (PmB), a rather selective inhibitor of protein kinase C, stopped (3H)thymidine incorporation with an IC50 of 10 microM when added 18 h before measuring DNA synthesis. Interestingly, PmB inhibition of DNA synthesis was suppressed when 4 nM 12-O-tetradecanoylphorbol-13-acetate was added along with PmB, indicating that PmB may act through inhibition of protein kinase C. In the node and spleen lymphocytes of normal guinea pigs, protein kinase C activity was entirely cytosolic and was eluted at 0.12 M NaCl when adsorbed on DEAE-cellulose. In L2C leukemic lymphocytes, total protein kinase C activity was of the same order of magnitude, but 20% of it was associated with the membrane fraction. The lipid-dependent activity, eluted at 0.12 M NaCl from cytosolic and membrane fractions, was suppressed by staurosporine with an IC50 of 10-40 nM and by polymyxin B with an IC50 of 2-6 microM. Phosphoinositide metabolism was studied in the transformed cells. Incorporation of 32Pi into polyphosphoinositides was considerable, whereas much more time was required for a tiny incorporation of inositol. We detected no release of radioactive inositol triphosphate. Taken together, these results suggest that protein kinase C function is indispensible for triggering L2C leukemic lymphocyte proliferation. The causes of this permanent activation merit further investigation.

Maitotoxin triggers the cortical reaction and phosphatidylinositol-4,5-bisphosphate breakdown in amphibian oocytes.

Maitotoxin, a potent marine toxin extracted from peredinians, was found to mimic fertilization in Xenopus oocytes and to trigger the breakdown of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2, the precursor of inositol 1,4,5-trisphosphate], an increase of intracellular pCa and the cortical reaction, including the exocytosis of cortical granules and a wave-like propagation of contraction in the animal hemisphere. All these effects of maitotoxin required the presence of external calcium. Moreover, the toxin considerably increased Ca2+ influx in amphibian oocytes arrested at first meiotic prophase, due to the permanent activation of voltage-dependent Ca2+ channels. Nevertheless it is doubtful that maitotoxin acts primarily as a Ca2+ ionophore or at the level of Ca2+ channels. Indeed no stimulation of Ca2+ uptake was observed in metaphase-II-arrested oocytes, although maitotoxin readily triggered the breakdown of PtdIns(4,5)P2 as well as the cortical reaction in such cells. On the other hand, PtdIns(4,5)P2 breakdown was not reduced in oocytes microinjected with EGTA, although the calcium chelator prevented the oocytes from undergoing the cortical reaction. Taken together, these findings support the view that the toxin might act primarily by increasing PtdIns(4,5)P2 phosphodiesterase activity.

Involvement of a calcium-phospholipid-dependent protein kinase in the maturation of Xenopus laevis oocytes.

It has been described that phosphorylation, and dephosphorylation, of specific proteins is associated with key events of the cell cycle and is likely to be due to activation of kinase(s). From our results, the presence of calcium-phospholipid-dependent protein kinase (PKC) was clearly demonstrated in both the cytosolic and particulate fractions of immature Xenopus laevis oocytes and in the cytosolic fraction of mature oocytes. However, it was less active in metaphase II- than in prophase I-arrested oocytes. The enzyme was partially purified by DEAE-cellulose and phenyl-Sepharose chromatography. It was activated in vitro by the tumor-promoting phorbol ester, 12-O-tetradecanoyl phorbol 13-acetate (TPA) as already described for PKC from other tissues. On the other hand, a calcium-phospholipid-independent histone kinase activity 4-fold higher in metaphase II- than in prophase I-arrested oocytes was detected. The possible role of PKC and phospholipid-independent histone kinase in the maturation process is discussed.

The effects of maitotoxin on phosphoinositides and calcium metabolism in a primary culture of aortic smooth muscle cells.

Maitotoxin, a potent marine toxin isolated from toxic tropical dinoflagellates and poisonous fishes induces contraction of different smooth muscle preparations. Actions of maitotoxin on phosphoinositides and calcium metabolism were studied using a primary culture of aortic smooth muscle cells. Maitotoxin induced a very large increase of cytosolic calcium concentration as evaluated by fura-2 acetoxymethyl ester fluorescence. This increase was concomitant with stimulation of inositol-phosphate accumulation and loss of viability of aortic smooth muscle cells. These responses to maitotoxin were abolished in Ca2+-free medium, and were mimicked by saponin. Calcium ionophores or K+ depolarisation did not induce inositol-phosphate formation. These results suggest that maitotoxin acts by altering smooth muscle cells permeability allowing a sustained calcium influx which is able to activate inositol-phosphate formation and which is lethal for the cells.

HIV F/3' orf encodes a phosphorylated GTP-binding protein resembling an oncogene product.

Apart from the retroviral gag, pol and env the HIV genome contains the F (3' orf) gene which encodes a polypeptide of 206 amino acids which is myristylated at the N-terminal and whose function is unknown. We have expressed the F gene in Escherichia coli and from a recombinant vaccinia virus, VVTGfHIV. The F-protein produced in VVTGfHIV-infected mammalian cells is myristilated, and is phosphorylated by protein kinase C at a residue close to the N-terminus like pp60-src (ref. 5). Purified bacterial F-protein also shows the GTPase, autophosphorylation and GTP-binding activities reported for the ras gene product. Furthermore, we show that expression of F in a CD4+ cell line down-regulates the CD4(T4) antigen. These results suggest that F is important in the pathophysiology of AIDS (acquired immune deficiency syndrome).