Optimal dose of sufentanil in children for intubation after sevoflurane induction without neuromuscular block.

BACKGROUND: We studied 63 ASA I children (age 2-8 yr) to determine the sufentanil dose needed to facilitate intubation under excellent conditions after inhalation induction with various end-tidal concentrations of sevoflurane without neuromuscular block. METHODS: Subjects were allocated randomly to receive sevoflurane end-tidal concentrations (e'(sevo)) of 2.5%, 3%, or 3.5%. Anaesthesia was induced with sevoflurane 6% without nitrous oxide for 2 min, and then inspired sevoflurane concentration was adjusted to keep e'(sevo) at 2.5%, 3%, or 3.5% according to the group. Subjects received i.v. sufentanil according to an 'up and down' design. Tracheal intubation by direct laryngoscopy was performed 6 min after sufentanil injection. Intubation was considered successful, if intubation conditions were excellent as determined by the laryngoscopist. RESULTS: The ED(50) [effective dose for 50% of subjects; mean (sd)] of sufentanil required for excellent intubation conditions was 0.6 (0.12), 0.32 (0.10), or 0.11 (0.07) microg kg(-1) for e'(sevo) of 2.5%, 3%, or 3.5%, respectively. Using logistic analysis, the 95% effective dose (ED(95)) of sufentanil was 1.02 [95% confidence intervals (CI) 0.31-1.74] microg kg(-1), 0.58 (95% CI 0.17-0.99) microg kg(-1), or 0.28 (95% CI 0.04-0.52) microg kg(-1) for e'(sevo) of 2.5%, 3%, or 3.5%, respectively. CONCLUSIONS: Excellent intubation conditions could be obtained in children after inhalation induction with low sevoflurane concentrations and adjuvant sufentanil.

Differential roles for cyclin-dependent kinase inhibitors p21 and p16 in the mechanisms of senescence and differentiation in human fibroblasts.

The irreversible G1 arrest in senescent human diploid fibroblasts is probably caused by inactivation of the G1 cyclin-cyclin-dependent kinase (Cdk) complexes responsible for phosphorylation of the retinoblastoma protein (pRb). We show that the Cdk inhibitor p21(Sdi1,Cip1,Waf1), which accumulates progressively in aging cells, binds to and inactivates all cyclin E-Cdk2 complexes in senescent cells, whereas in young cells only p21-free Cdk2 complexes are active. Furthermore, the senescent-cell-cycle arrest occurs prior to the accumulation of the Cdk4-Cdk6 inhibitor p16(Ink4a), suggesting that p21 may be sufficient for this event. Accordingly, cyclin D1-associated phosphorylation of pRb at Ser-780 is lacking even in newly senescent fibroblasts that have a low amount of p16. Instead, the cyclin D1-Cdk4 and cyclin D1-Cdk6 complexes in these cells are associated with an increased amount of p21, suggesting that p21 may be responsible for inactivation of both cyclin E- and cyclin D1-associated kinase activity at the early stage of senescence. Moreover, even in the late stage of senescence when p16 is high, cyclin D1-Cdk4 complexes are persistent, albeit reduced by

The Saccharomyces cerevisiae homologue of human Wiskott-Aldrich syndrome protein Las17p interacts with the Arp2/3 complex.

Yeast Las17 protein is homologous to the Wiskott-Aldrich Syndrome protein, which is implicated in severe immunodeficiency. Las17p/Bee1p has been shown to be important for actin patch assembly and actin polymerization. Here we show that Las17p interacts with the Arp2/3 complex. LAS17 is an allele-specific multicopy suppressor of ARP2 and ARP3 mutations; overexpression restores both actin patch organization and endocytosis defects in ARP2 temperature-sensitive (ts) cells. Six of seven ARP2 ts mutants and at least one ARP3 ts mutant are synthetically lethal with las17Delta ts confirming functional interaction with the Arp2/3 complex. Further characterization of las17Delta cells showed that receptor-mediated internalization of alpha factor by the Ste2 receptor is severely defective. The polarity of normal bipolar bud site selection is lost. Las17-gfp remains localized in cortical patches in vivo independently of polymerized actin and is required for the polarized localization of Arp2/3 as well as actin. Coimmunoprecipitation of Arp2p with Las17p indicates that Las17p interacts directly with the complex. Two hybrid results also suggest that Las17p interacts with actin, verprolin, Rvs167p and several other proteins including Src homology 3 (SH3) domain proteins, suggesting that Las17p may integrate signals from different regulatory cascades destined for the Arp2/3p complex and the actin cytoskeleton.

[Carbon monoxide exposure in automobile garages: evaluation of mechanics]. / Exposition a l'oxyde de carbone dans les garages d'automobiles: evaluation chez les mecaniciens.

Carbon monoxyde (CO) exposure is an occupational hazard for car mechanics. Following two cases of CO poisoning and a preliminary environmental assessment of four car dealerships, a descriptive study was initiated in 76 car dealer repair shops in the Quebec City area to evaluate CO exposure. Alveolar CO of 496 mechanics and ambient CO in 47 car dealer repair shops were measured: 44.6% of non smoker workers had an alveolar CO level greater than 27 ppm which is equivalent to a 5% level of carboxyhemoglobin (HbCO). Ambient CO was greater than 35 ppm in 42.6% of car repair shops, a level considered a risk for chronic health effects. The following measures were proposed to car dealership owners to reduce mechanics' exposure to CO: 1) Install or improve local or general ventilation systems, 2) improve the layout of the repair shops, and 3) prohibit running of car engines without proper connection to the ventilation system.

Asymmetry of Bispectral Index (BIS) in severe brain-injured patients treated by barbiturates with unilateral or diffuse brain injury.

OBJECTIVE: Bispectral index (BIS) may be used in traumatic brain-injured patients (TBI) with intractable intracranial hypertension to adjust barbiturate infusion but it is obtained through a unilateral frontal electrode. The objective of this study was to evaluate differences in BIS between hemispheres in two groups: unilateral frontal (UFI) and diffuse (DI) injured. PATIENTS AND METHODS: Prospective monocenter observational study in 24 TBI treated with barbiturates: 13 UFI and 11 DI. Simultaneous BIS and EEG was recorded for 1h. Goal of monitoring was a left BIS between 5 and 15. Biases in BIS were considered as clinically relevant if greater than 5. Differences in biases were interpreted from both statistical (Mann-Whitney test) and clinical points of view. RESULTS: Mean BIS in the two hemispheres remained in the same monitoring range. There were statistic and clinical differences in some values in the two groups of patients (15% of bias greater than I5I in UFI group and 10% in DI group). BIS monitoring allowed the adequate number of bursts/minutes to be predicted in 18 patients and did not detect an overdosage in 2. CONCLUSIONS: While asymmetric BIS values in TBI patients occur whatever the kind of injury, they were not found to be clinically relevant in most of these heavily sedated patients. Asymmetrical BIS monitoring might be sufficient to monitor barbiturate infusion in TBI provided that the concordance between BIS and EEG is regularly checked.

The WASP/Las17p-interacting protein Bzz1p functions with Myo5p in an early stage of endocytosis.

The formation of actin filaments is crucial for endocytosis and other interrelated cellular phenomena such as motility, polarized morphogenesis, and cytokinesis. In this paper we have investigated the role of the WASP/Las17-interacting protein Bzz1p in endocytosis and trafficking to the vacuole. We and others have recently shown that Bzz1p is an actin patch protein that interacts directly with Las17p via a SH3-polyproline interaction. Bzz1p functions with type I myosins to restore polarity of the actin cytoskeleton after NaCl stress. In an in vitro bead assay, GST-Bzz1p fusion protein triggers a functional actin polymerization machinery through its two C-terminal SH3 domains. In this paper we implicate Bzz1p with the type I myosins both in fluid-phase and in the internalization step of receptor-mediated endocytosis. As deduced from their localization as GFP fusions, the vacuolar delivery of endocytic and biosynthetic cargoes as well as the multivesicular body pathway appear unaffected. We further elucidate Bzz1p direct participation in actin polymerization by demonstrating that each of the SH3 domains of Bzz1p individually is able to trigger actin polymerization in a cell-free system dependent on Arp2/3, Las17p, Vrp1p, and the type I myosins. Taken together, our results show that Bzz1p participates, essentially via its SH3 domains, in early steps of endocytosis together with known actin nucleation activators.

SH3 domain-containing proteins and the actin cytoskeleton in yeast.

SH3 (Src homology-3) domains are involved in protein-protein interactions through proline-rich domains. Many SH3-containing proteins are implicated in actin cytoskeleton organization. The aim of our ongoing work is to study the functions of the SH3-containing proteins in actin cytoskeleton regulation. The yeast Saccharomyces cerevisiae proteome includes 29 SH3 domains distributed in 25 proteins. We have examined the direct involvement of these SH3 domains in actin polymerization using an in vitro polymerization assay on GST (glutathione S-transferase)-SH3-coated beads. As expected, not all SH3 domains show polymerization activity, and many recruit distinct partners as assessed by microscopy and pull-down experiments. One such partner, Las17p, the yeast homologue of WASP (Wiskott-Aldrich syndrome protein), was assayed because it stimulates actin nucleation via the Arp2/3 (actin-related protein 2/3) complex. Ultimately, proteins involved in specific biological processes, such as membrane trafficking, may also be recruited by some of these SH3 domains, shedding light on the SH3-containing proteins and actin cytoskeleton functions in these processes.