Anesthesie generale versus anesthesie perimedullaire.

in Revue Médicale de Liège (1999), 54(7), 588-92

Perimedullary anesthetic techniques (epidural or spinal anesthesia), by themselves or combined with general anesthesia offer several advantages in the postoperative period when compared with general ... [more ▼]

Perimedullary anesthetic techniques (epidural or spinal anesthesia), by themselves or combined with general anesthesia offer several advantages in the postoperative period when compared with general anesthesia alone. The incidence of postoperative respiratory and cardiovascular complications is decreased. The physiologic stress reaction, with its associated hypercoagulable state and immune depression, is attenuated. Finally, the resumption of gastrointestinal function is hastened. These benefits of central neural blockade are noted most clearly when the techniques are used for several days postoperatively, most often by catheter based epidural analgesia. The use of local anesthetic agents in the analgesic mixture would appear to be important. This is likely because these substances inhibit the sympathetic nervous system and spinal reflex axes. The role of this inhibition in the advantages of perimedullary techniques is probably important. It is important to note that inhibition of the sympathatetic nervous system can be associated with indesirable consequences in certain patients. These techniques must therefore be used cautiously, and patients who benefit from them must receive careful surveillance. [less ▲]

Hemodynamic changes and catecholamine release during laparoscopic adrenalectomy for pheochromocytoma.

in Anesthesia and Analgesia (1999), 88(1), 16-21

We investigated hemodynamics and plasma catecholamine concentrations in eight consecutive patients undergoing laparoscopic adrenalectomy for suspected pheochromocytoma. The same anesthesia protocol was ... [more ▼]

We investigated hemodynamics and plasma catecholamine concentrations in eight consecutive patients undergoing laparoscopic adrenalectomy for suspected pheochromocytoma. The same anesthesia protocol was used in all patients: a continuous infusion of sufentanil 0.5 microg x kg(-1) x h(-1) and isoflurane 0.4% (end-tidal) in 50% N2O/O2. Systolic arterial pressure was maintained between 120 and 160 mm Hg by adjusting an infusion of nicardipine, a calcium-channel blocker, while tachycardia (>100 bpm) was treated by 1-mg boluses of atenolol. Hemodynamics (thermodilution technique) and plasma catecholamine concentrations were measured before surgery, after the induction of anesthesia, after turning the patient to the lateral position, during pneumoperitoneum, during tumor manipulation, after adrenalectomy, and at the end of surgery. Two events resulted in significant catecholamine release: creation of the pneumoperitoneum and adrenal gland manipulation. As a consequence, a twofold increase in cardiac output was recorded. Adjustments of nicardipine infusion (2-6 microg x kg(-1) x min(-1)) minimized changes in mean arterial pressure. Beta-adrenergic blockade was necessary in six patients. In conclusion, laparoscopic adrenalectomy for pheochromocytoma results in marked catecholamine release during pneumoperitoneum and tumor manipulation. Titration of a nicardipine infusion allowed easy and quick control of the hemodynamic aberrancies related to these processes. IMPLICATIONS: Pneumoperitoneum during laparoscopy, now used for adrenalectomy, may complicate anesthetic management of patients with pheochromocytoma. In this study, laparoscopic adrenalectomy was associated with catecholamine release during the creation of pneumoperitoneum and tumor manipulation. Adjustments of a nicardipine infusion readily attenuated the subsequent hemodynamic aberrancies. [less ▲]

Red blood cell substitutes: fluorocarbon emulsions and haemoglobin solutions.

in British Medical Bulletin (1999), 55(1), 277-98

The problems posed by transfusion of homologous blood have led to the development of substances able to replace the gas transporting properties of blood. Perfluorocarbons (PFCs) emulsions and modified ... [more ▼]

The problems posed by transfusion of homologous blood have led to the development of substances able to replace the gas transporting properties of blood. Perfluorocarbons (PFCs) emulsions and modified haemoglobin (Hb) solutions have been developed for this goal and are now tested in clinical assays. PFCs are synthetic fluorinated hydrocarbons, capable of dissolving large quantities of oxygen (O2; without binding) at high inspired concentrations of O2, and of delivering this O2 to the tissues. They are administered as emulsions containing particles with a diameter of approximately 0.2 micron, capable of entering the microcirculation. They are eliminated unchanged by the lungs within several days. Fluosol-DA 20% was the first PFC emulsion used in clinical practice. Currently, Oxygent, a second generation PFC emulsion, is being evaluated in clinical studies. The PFCs are not blood substitutes, but rather a means to ensure tissue oxygenation during extreme haemodilution. Solutions of free Hb do not have the antigenic characteristics of the blood groups, and do not require compatibility testing. They are fully saturated with O2 at ambient FiO2. The Hbs used are derived from either human or bovine sources, or via recombinant DNA technology. In order to maintain satisfactory intravascular half-life and O2 affinity, the Hb molecules are modified by adding internal crosslinks, by polymerization, and/or by encapsulation. After promising animal studies, several of these modified Hb solutions are now being studied in Phase III clinical trials. Among them, diaspirin cross-linked haemoglobin (DCLHb) has been used in cardiac and orthopaedic surgery, and for resuscitation of traffic accident victims. The initial results of multicentre trials are now being analysed. [less ▲]

Oxygen therapy in intensive care patients: a vital poison?

in Vincent, Jean-Louis (Ed.) Yearbook of intensive care and emergency medicine (1999)

Equine Neutrophil Myeloperoxidase in Plasma: Design of a Radio-Immunoassay and First Results in Septic Pathologies

in Veterinary Immunology and Immunopathology (1998), 66(3-4), 257-71

The strangulated intestinal pathologies of horses are accompanied by a local activation of the neutrophils, that can be revealed by measuring the tissular enzymatic activity of the granulocytic enzyme ... [more ▼]

The strangulated intestinal pathologies of horses are accompanied by a local activation of the neutrophils, that can be revealed by measuring the tissular enzymatic activity of the granulocytic enzyme myeloperoxidase (MPO). To estimate the possible spreading of this neutrophil activation to the systemic circulation, we designed a radioimmunoassay (RIA) for equine neutrophil myeloperoxidase (MPO) (EC 1.11.1.7) using a specific rabbit antiserum. MPO was labeled with 1 mCi 125I by a technique of self-labeling in the presence of 10(-4) M hydrogen peroxide. The RIA was performed by incubation of 100 microl diluted antiserum, 100 microl labeled MPO (+/-30,000 cpm) and 100 microl of the reference molecule (unlabeled MPO) solution or the unknown sample, at room temperature for 18 h. The antibody-antigen complexes were isolated by double antibody precipitation. The sensitivity of the RIA was 2 ng/ml. The RIA showed good precision and accuracy with intra- and inter-assay coefficients of variation 6% and 8%, respectively, for MPO concentrations ranging from 2 ng/ml to 60 ng/ml. The best sampling technique for MPO measurement in plasma was to collect blood into EDTA, which allowed us to get a plasmatic value stable with time. The mean MPO value in normal horses was 69.5 +/- 19.4 ng/ml in EDTA anticoagulated plasma (n = 48). The stress of transport and anaesthesia did not modify the mean plasmatic value of MPO. No significant increase of plasma MPO was observed in 17 horses submitted to surgery for pathologies without systemic impact. But, in 25 horses with obstructive intestinal pathologies, persistent abnormal MPO concentrations were measured (until 740 ng/ml). [less ▲]

An Electron Spin Resonance (Esr) Study on the Mechanism of Ascorbyl Radical Production by Metal-Binding Proteins

in Biometals (1998), 11(2), 81-8

The mechanism of ascorbate oxidation by metal-binding proteins (ceruloplasmin, albumin and transferrin) was investigated in vitro and in isolated plasma by the measurement of the ascorbyl free radicals ... [more ▼]

The mechanism of ascorbate oxidation by metal-binding proteins (ceruloplasmin, albumin and transferrin) was investigated in vitro and in isolated plasma by the measurement of the ascorbyl free radicals (AFR) by electron spin resonance (ESR). In plasma of 13 healthy volunteers, a spontaneous and variable production of AFR was detected, which was increased by a 10(-4) M ascorbate overloading; however, this increase was not correlated to the intensity of the spontaneous AFR signal. The addition of Cu2+ and ceruloplasmin to plasma increased the ESR signal, while the addition of transferrin decreased the signal intensity in a dose-dependent manner. In vitro, we demonstrated that ascorbate was oxidized by human serum albumin and by ceruloplasmin, and that this oxidase-like activity was lost by trypsin or heat treatment of these proteins. These two proteins positively interacted in the oxidation of ascorbate, since addition of crude albumin to a solution of ascorbate and ceruloplasmin increased the intensity of ESR signal in a dose-dependent manner. The treatment of albumin by a metal chelator (DDTC) abolished these positive interactions. The respective roles of copper and iron in ascorbate oxidation were studied and showed a dose-dependent effect of these ions on ascorbate oxidation. The role of iron was confirmed by the inhibiting effect of metal-free transferrin on iron-dependent ascorbate oxidation. Concerted actions between iron carrying albumin and copper carrying ceruloplasmin appear responsible for the production of AFR in vitro and in vivo. [less ▲]

Etat actuel des transplantations d'organes: place à la xénotransplantation?

in Revue Médicale de Liège (1998), 53(2), 97-102

In the last few years, transplantation was an area of intense research activity. However, there is a worldwide shortage of donor organs for clinical transplantations. Currently, interest in ... [more ▼]

In the last few years, transplantation was an area of intense research activity. However, there is a worldwide shortage of donor organs for clinical transplantations. Currently, interest in xenotransplantation research is growing not only because of the increased demand for organs but also because of advances in molecular biology techniques that make possible the genetic or immunological manipulations of the animal donor rather than the human recipient. The better definitions of the mechanisms responsible for xenograft rejection should facilitate appropriate therapeutic strategies for long xenograft survival. [less ▲]

The Antibiotic Ceftazidime Is a Singlet Oxygen Quencher as Demonstrated by Ultra-Weak Chemiluminescence and by Inhibition of Aap Consumption

in Biochimica et Biophysica Acta (1998), 1379(1), 61-8

We demonstrated that the cephalosporin antibiotic ceftazidime (CAZ) deactivated singlet oxygen (1O2). We then studied the mechanisms of the CAZ effects on the ultra weak chemiluminescence (uwCL ... [more ▼]

We demonstrated that the cephalosporin antibiotic ceftazidime (CAZ) deactivated singlet oxygen (1O2). We then studied the mechanisms of the CAZ effects on the ultra weak chemiluminescence (uwCL) associated with the energy decay of 1O2 generated by the Mallet reaction (H2O2 + HOCl --> HCl + H2O + 1O2), and on the anthracene-9,10-dipropionic acid (AAP) consumption by 1O2 generated by irradiation of Rose Bengal (RB). The uwCL generated by the Mallet reaction was amplified (6.2 times) by CAZ. The use of red and blue filters, which absorb radiation below 610 nm and between 470 and 700 nm respectively, demonstrated that CAZ increased the uwCL by a radiation emission at wavelengths shorter than the 633 and 704 nm wavelength emissions of 1O2. CAZ was excited by scavenging the energy excess of 1O2, which so returned to its fundamental state, while CAZ deactivated with light emission between 430-480 nm. CAZ also inhibited in a dose-dependent manner the consumption of AAP by 1O2 generated by the irradiation of RB. The protection of AAP by 5 x 10(-3) M CAZ was equivalent to that of 10(-3) M histidine and 3 X 10(-6) M sodium azide. This process of 1O2 deactivation will be useful in diseases characterized by an excessive PMN activation with a release of activated oxygen species. [less ▲]

Equine neutrophil myeloperoxidase in plasma: design of a radio-immunoassay and first results in septic pathologies.

in Veterinary Immunology and Immunopathology (1998), 66(3-4), 257-71

The strangulated intestinal pathologies of horses are accompanied by a local activation of the neutrophils, that can be revealed by measuring the tissular enzymatic activity of the granulocytic enzyme ... [more ▼]

The strangulated intestinal pathologies of horses are accompanied by a local activation of the neutrophils, that can be revealed by measuring the tissular enzymatic activity of the granulocytic enzyme myeloperoxidase (MPO). To estimate the possible spreading of this neutrophil activation to the systemic circulation, we designed a radioimmunoassay (RIA) for equine neutrophil myeloperoxidase (MPO) (EC 1.11.1.7) using a specific rabbit antiserum. MPO was labeled with 1 mCi 125I by a technique of self-labeling in the presence of 10(-4) M hydrogen peroxide. The RIA was performed by incubation of 100 microl diluted antiserum, 100 microl labeled MPO (+/-30,000 cpm) and 100 microl of the reference molecule (unlabeled MPO) solution or the unknown sample, at room temperature for 18 h. The antibody-antigen complexes were isolated by double antibody precipitation. The sensitivity of the RIA was 2 ng/ml. The RIA showed good precision and accuracy with intra- and inter-assay coefficients of variation 6% and 8%, respectively, for MPO concentrations ranging from 2 ng/ml to 60 ng/ml. The best sampling technique for MPO measurement in plasma was to collect blood into EDTA, which allowed us to get a plasmatic value stable with time. The mean MPO value in normal horses was 69.5 +/- 19.4 ng/ml in EDTA anticoagulated plasma (n = 48). The stress of transport and anaesthesia did not modify the mean plasmatic value of MPO. No significant increase of plasma MPO was observed in 17 horses submitted to surgery for pathologies without systemic impact. But, in 25 horses with obstructive intestinal pathologies, persistent abnormal MPO concentrations were measured (until 740 ng/ml). [less ▲]

Propofol reacts with peroxynitrite to form phenoxyl radicals. Demonstration by ESR

in Biochemical and Biophysical Research Communications (1998), 249