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Biomedical subjects

M Lamy

Publications and source records attributed to M Lamy.

At least 73 records · Page 4Linked to original sources
PubMed1999

[General anesthesia vs perimedullary anesthesia].

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.

Anesthesia, Epidural↗
PubMed1999

[Epidemiology of various oral-dental problems in aging patients].

Demographic projections show an important increase of the elderly population. The percentage of complete edentulous elderly patients is decreasing but their total number will remain constant. The prevalence of caries (essentially root caries) and of periodontal disease is, actually, very important. The increase of remaining teeth in the aging population, is a risk for a higher prevalence of these problems. It's time to become aware of this situation and to develop prevention and adapted treatments for this population.

Aged↗
PubMed1999

[Oral dryness in geriatric patients].

Dry mouth is usual in geriatrics. It doesn't seem a age related change of salivary gland tissues, but as often as not, it results from the use of some drugs. Seventy percents of institutionalised elderly population consummate these medications with buccal significance. This publication tries to summarize the means of diagnosis and the possibilities to treat this pathology.

Aged↗
PubMed1998

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

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).

Anesthesia↗
PubMed1998

Interactions between lipopolysaccharides and blood factors on the stimulation of equine polymorphonuclear neutrophils.

In horses, the mechanisms of lipopolysaccharide (LPS) stimulation of isolated neutrophils to produce reactive oxygen species remain unknown. We re-investigated this problem by monitoring the luminol-enhanced chemiluminescence (CL) produced by LPS-stimulated equine neutrophils. The neutrophils were isolated from horse blood by discontinuous density gradient centrifugation (> or = 99% neutrophils; viability > or = 98%). Increasing concentrations of Escherichia coli (E. coli) LPS (from 0.01-10 microg ml(-1)) were used to activate the neutrophils. When LPS was used directly, without another stimulator, the respiratory burst of neutrophils was not activated (N=12 horses; n=5 assays per horse). On the contrary, when LPS was added to whole blood, the neutrophils isolated from this blood were stimulated in a LPS dose-dependent manner, but polymyxin B added to whole blood suppressed this stimulation (N=2; n=6). LPS dissolved in autologous equine plasma stimulated the isolated neutrophils in a dose-dependent manner from 0.1-10 microg ml(-1) (N=5; n=12). Heat inactivation of the plasma abolished this CL increase (N=2; n=5). LPS added to equine albumin did not stimulate the isolated neutrophils (N=2; n=5). On the contrary, the addition of gamma-globulins (1 mg ml(-1)) to LPS (10 microg ml(-1)) led to the stimulation of neutrophils (N=2; n=5). We concluded that LPS did not directly stimulate the isolated equine neutrophils, but that plasmatic factors are needed for the stimulation of these cells by LPS.

Animals↗
PubMed1998

Propofol reacts with peroxynitrite to form a phenoxyl radical: demonstration by electron spin resonance.

Peroxynitrite (ONOO-), resulting from the reaction of nitric oxide with superoxide anion, is a powerful oxidant produced in activated macrophages, during ischemia-reperfusion processes as well as in neurodegenerative disorders. This study investigated the reaction of the anesthetic agent propofol (PPF) with ONOO-, using electron spin resonance (ESR) and UV-visible spectrometry. Peroxynitrite was synthetized either from acidified hydrogen peroxide and nitrite, or from sodium azide and ozone. The addition of ONOO- to PPF in alkaline solution (pH 12) allowed to detect a, short lifetime, ESR signal corresponding to a phenoxyl radical. This finding was confirmed by a UV-visible study, resulting in the appearance of 427 nm peak and the disappearance of the peak located at 239 nm. The 291 nm peak remained unchanged. The identification of the end-product of the reaction of PPF with ONOO- needs further investigations.

Anesthetics↗
PubMed1998

Comparative effects of University of Wisconsin and Euro-Collins solutions on pulmonary mitochondrial function after ischemia and reperfusion.

BACKGROUND: The aim of this study was to compare the effects of Euro-Collins and University of Wisconsin solutions on pulmonary mitochondrial function after cold ischemia and subsequent warm reperfusion. METHODS: Seventeen pigs underwent lung harvesting after classical lung flush with either University of Wisconsin or Euro-Collins solutions. The mitochondria were isolated from fresh swine lungs, from swine lungs subjected to 24 hr of cold ischemia, and from swine lungs subjected to 24 hr of ischemia followed by 30 min of subsequent ex vivo reperfusion at 37 degrees C with Krebs-Henseleit buffer solution and air ventilation. Mitochondrial oxidative phosphorylation parameters were determined in isolated mitochondria by in vitro measurement of oxygen consumption rates. During reperfusion, the lung function was assessed by the pulmonary aerodynamic parameters and the pulmonary vascular resistance. RESULTS: Relative to controls, mitochondria submitted to cold ischemia showed an alteration in the oxidoreductase activities of the respiratory chain. However, the yield of oxidative phosphorylation was conserved. After reperfusion, pulmonary mitochondria underwent a significant worsening in the oxidoreductase activities of the respiratory chain, and a decrease in the respiratory control and the efficiency of oxidative phosphorylation. Meanwhile, the reperfused lungs showed evidence of early dysfunction, assessed by the aerodynamic parameters and pulmonary vascular resistance. In this model, there was no advantage of University of Wisconsin solution over Euro-Collins solution. CONCLUSIONS: The mild mitochondrial alterations after cold ischemia were not sufficient to explain the limited tolerance of lung to ischemia. After reperfusion, the mitochondrial damage was more severe and could be involved in the posttransplant lung dysfunction.

Adenosine↗
PubMed1998

The antibiotic ceftazidime is a singlet oxygen quencher as demonstrated by ultra-weak chemiluminescence and by inhibition of AAP consumption.

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.

Anthracenes↗
PubMed1998

The American-European Consensus Conference on ARDS, part 2. Ventilatory, pharmacologic, supportive therapy, study design strategies and issues related to recovery and remodeling.

The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last ten years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathological features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.

Americas↗
PubMed1998

Antithrombin III in patients with severe sepsis. A randomized, placebo-controlled, double-blind multicenter trial plus a meta-analysis on all randomized, placebo-controlled, double-blind trials with antithrombin III in severe sepsis.

OBJECTIVES: To evaluate the safety and potential efficacy of antithrombin III (AT III) in reducing mortality in patients with severe sepsis. DESIGN: Prospective, randomized, placebo-controlled, double-blind, phase II, multicenter, multinational clinical trial. SETTING: Seven academic medical center intensive care units (ICU) in Belgium, Denmark, the Netherlands, Norway and Sweden. PATIENTS: 42 patients with severe sepsis who received standard supportive care and antimicrobial therapy, in addition to the administration of AT III or placebo. INTERVENTIONS: Patients received either an intravenous loading dose of 3000 IU AT III followed by a maintenance dose of 1500 IU every 12 h for 5 days or equivalent amounts of placebo. MEASUREMENTS AND RESULTS: All patients were evaluated for safety and for 30-day all-cause mortality. CONCLUSIONS: The administration of AT III was safe and well-tolerated. It was followed by a 39 % reduction in 30-day all-cause mortality (NS). The reduction in mortality was accompanied by a considerably shorter stay in the ICU. Patients treated with AT III exhibited a better performance in overall severity of illness and organ failure scores (Acute Physiology and Chronic Health Evaluation II, multiple organ failure, organ system failure), which was noticeable soon after initiation of treatment. Patients treated with AT III demonstrated a better resolution of pre-existing organ failures and a lower incidence of new organ failures during the observation period. A meta-analysis comprising this and two other double-blind, placebo-controlled trials with AT III with a total of 122 patients suffering from severe sepsis confirms the positive trend. The results of the meta-analysis demonstrate a 22.9 % reduction in 30-day all-cause mortality in patients treated with AT III. Although still too small to be confirmative, the meta-analysis clearly points to the fact that a sufficiently powered phase III trial is warranted to prove whether AT III has a beneficial role in the treatment of severe sepsis.

APACHE↗
PubMed1998

Endotoxaemia, production of tumour necrosis factor alpha and polymorphonuclear neutrophil activation following strenuous exercise in humans.

To examine whether endotoxaemia accompanying long-term, strenuous physical exercise is involved in exercise-induced increase in plasma tumour necrosis factor alpha (TNF-alpha) concentration and polymorphonuclear neutrophil (PMN) activation, 14 male recreational athletes [mean age 28 (SEM 1) years] were studied. Exercise consisted of a 1.5-km river swim, a 40-km bicycle race, and a 10-km road race. Mean time to complete the race was 149.8 (SEM 4.8) min. The plasma concentrations of granulocyte myeloperoxidase (MPO) and TNF-alpha were significantly higher than baseline values immediately and 1 h after exercise (P<0.001). Both variables returned to pre-race levels the day after exercise. Marked, transient decreases in plasma concentrations of anti-lipopolysaccharide (LPS) immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies directed against a panel of selected smooth gram-negative LPS were observed after the race, reaching in most cases minimal values in the blood sample drawn immediately following the completion of the triathlon. There was no significant correlation between the magnitude of PMN activation, as assessed by the increase in plasma concentrations of MPO, and the humoral markers of endotoxaemia and TNF-alpha. An inverse, highly significant relationship between the increase in plasma TNF-alpha concentrations and the changes in circulating anti-LPS IgM antibodies concentrations was observed (r = -0.7; P<0.01). These findings suggest that exercise-induced endotoxaemia was involved in the release of TNF-alpha, that the magnitude of the TNF-alpha response to exercise was down-regulated by anti-LPS antibodies of the IgM class, and that the production of TNF-alpha and endotoxaemia did not seem to play a role in the activation of circulating PMN in the exercising subjects.

Adult↗
PubMed1998

An electron spin resonance (ESR) study on the mechanism of ascorbyl radical production by metal-binding proteins.

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.

Adult↗
PubMed1998

Clinical experience with antithrombin III concentrates in critically ill patients with sepsis and multiple organ failure.

Despite improvements in critical care medicine and the development and aggressive use of potent broad-spectrum anti-microbial agents, mortality due to severe sepsis has not changed during the recent years and still comes to 35% to 45%. For quite a long time our understanding of the pathophysiology of sepsis was mainly focused on endotoxin and proinflammatory cytokines like tumor necrosis factor or interleukin-1. Now it is generally accepted that many signs and symptoms of sepsis are not directly mediated by cytokines but are transmitted through other mediator systems. The coagulation system comes into play especially when the septic process progresses to malperfusion and organ failure. Antithrombin III is an important inhibitor of the intrinsic, extrinsic and common pathway of coagulation. Recently, evidence has been accumulating that there is an additional anti-inflammatory potential of the drug. Currently there are several clinical trials ongoing to investigate whether this effect is of clinical relevance in the treatment of patients with severe sepsis.

Antithrombin III↗
PubMed1998

Possible in vivo tolerance of human polymorphonuclear neutrophil to low-grade exercise-induced endotoxaemia.

To address the question of whether translocation of bacterial lipopolysaccharide (LPS) into the blood could be involved in the process of exercise-induced polymorphonuclear neutrophil (PMN) activation, 12 healthy male subjects who took part in a sprint triathlon (1.5 km river swim, 40 km bicycle race, 10 km road race) were studied. While there was no detectable amount of endotoxin in the blood samples drawn at rest, exercise was followed by the appearance of circulating endotoxin molecules at the end of competition in four subjects, and after one and 24 h recovery in three and seven athletes, respectively. The concentrations of plasma granulocyte myeloperoxidase ([MPO]), were significantly higher immediately after exercise and one hour later-than baseline values (P<0.001). This variable returned to pre-race levels the day after exercise, despite the presence of detectable amounts of LPS, at that time, in seven athletes. The absence of significant correlation (r=0.26; P=0.383) and temporal association between [MPO] and plasma endotoxin levels led us to conclude that endotoxaemia was not involved in the process of exercise-induced PMN degranulation observed in our subjects.

Adult↗
PubMed1998

Protective activity of propofol, Diprivan and intralipid against active oxygen species.

We separately studied the antioxidant properties of propofol (PPF), Diprivan (the commercial form of PPF) and intralipid (IL) (the vehicle solution of PPF in Diprivan) on active oxygen species produced by phorbol myristate acetate (10(-6) M)-stimulated human polymorphonuclear leukocytes (PMN: 5 x 10(5) cells/assay), human endothelial cells (5 x 10(5) cells/assay) or cell-free systems (NaOCl or H2O2/peroxidase systems), using luminol (10(-4) M)-enhanced chemiluminescence (CL). We also studied the protective effects of Diprivan on endothelial cells submitted to an oxidant stress induced by H2O2/MPO system: cytotoxicity was assessed by the release of preincorporated 51Cr. Propofol inhibited the CL produced by stimulated PMN in a dose dependent manner (until 5 x 10(-5) M, a clinically relevant concentration), while Diprivan and IL were not dose-dependent inhibitors. The CL produced by endothelial cells was dose-dependently inhibited by Diprivan and PPF, and weakly by IL (not dose-dependent). In cell free systems, dose-dependent inhibitions were obtained for the three products with a lower effect for IL. Diprivan efficaciously protected endothelial cells submitted to an oxidant stress, while IL was ineffective. By HPLC, we demonstrated that PPF was not incorporated into the cells. The drug thus acted by scavenging the active oxygen species released in the extracellular medium. IL acted in the same manner, but was a less powerful antioxidant.

Antioxidants↗
PubMed1998

The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome.

The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last 10 years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathologic features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.

Europe↗