Low-dose intravenous ketamine and clonidine for poor postoperative opioid responsiveness: a double blind randomized study.

In the immediate postoperative period, some patients present with pain that responds poorly to intravenous opioids. In a double-blind randomized study, we tested the hypothesis that administering small doses of intravenous ketamine (0.125 mg/kg) combined with clonidine (0.5 microg/kg) would enhance the speed of onset and the quality of an opioid analgesic regimen in patients who initially responded poorly to opioids. We enrolled 68 patients in the study, all physical status I to III according to the American Society of Anesthesiologists classification. If the patient's numerical rating scale (NRS) score remained > or = 5 after an initial intravenous injection of 10 mg piritramide (2-mg boluses every 5 minutes) in the post-anesthesia care unit, patients were randomized to either intravenous placebo (sodium chloride 0.9%) or active substances (ketamine 0.125 mg/kg plus clonidine 0.5 microg/kg). Fifteen minutes after administration of either placebo or active agents, patients with severe pain (NRS > 4) again received intravenous opioids until NRS < 4. The primary endpoint of the study was to reduce by 20 minutes the time necessary to achieve an NRS < 4. There was no statistically significant difference between the two groups regarding the time required for patients to achieve an NRS < 4. It was concluded that in the immediate postoperative period, the acute administration of small combined doses of intravenous ketamine (0.125 mg/kg) and clonidine (0.5 mirog/kg) does not reduce the onset of an opioid-based analgesia in patients with an initial poor response to intravenous opioids.

[Effect of rhDNase on the respiratory function and nutritional status of children and adolescents with mucoviscidosis]. / Effects de la rhDNase sur la fonction respiratoire et le statut nutritionnel de l'enfant et de l'adolescent atteints de mucoviscidose.

BACKGROUND: In 1994 we started recombinant human deoxyribonuclease (rhDNase) in every cystic fibrosis (CF) patient whatever his (her) clinical condition, provided they were aged more than 5 years and forced vital capacity (FVC) was > or = 40%. POPULATION AND METHODS: We reviewed retrospectively the effects of rhDNase in 69 CF children and adolescents during a 2-year follow-up. Patients (35 boys, 34 girls) received 2.5 mg of rhDNase once daily from a mean age of 8.5 years (range 5-16.4). Baseline spirometric values (% predicted) and nutritional status were as followed: FVC = 84.8 +/- 21.7; forced expiratory volume in 1 second (FEV1) = 80.8 +/- 22.2; peak flow = 89.7 +/- 34.2, forced expiratory fraction 25-75% (FEF 25-75) = 71.8 +/- 32.8; Z score weight/height = -0.41 +/- 1.14; Z score weight/age = -0.48 +/- 1.25, body mass index = 15.4 +/- 1.8; caloric intake = 107 +/- 25% of recommended dietary allowances (RDA). Patients had a Shwachman-Kulczycki's score of 87 +/- 9. Spirometric and nutritional data were analysed after 1, 3, 6, 12, 18 and 24 months of treatment and compared to baseline values (changes evaluated as percent change from mean baseline for spirometric data). Shwachman-Kulczycki's score was calculated after 24 months of rhDNase. RESULTS: An improvement of FVC (+10.7%, P < 0.001) and FEV1 (+12%, P < 0.01) was noted after one month of treatment and was maintained throughout the following 2 years around 8.7% (6.4-11.4) for FVC and 8.2% (7.3-9.1) for FEV1, P < or = 0.01. This was particularly observed in children aged 5 to 10 years, in boys and in patients with a baseline FVC under 70% predicted. There was no significant change in FEF 25-75. We observed an improvement of daily caloric intake from the third month (P < 0.05) and of body mass index from the sixth month (P = 0.02). This was particularly noted in girls. Z score weight/age was improved only during the first 3 months of treatment while Z score weight/height increased only after a 2 year follow-up. There was no significant change in Shwachman-Kulczycki's score after 24 months of rhDNase. CONCLUSION: rhDNase in CF children in effective on lung function as well as on nutritional status and the response to this treatment can be evaluated after the first 3 months.

Role of neutrophils in gastric damage induced by platelet activating factor.

Platelet-activating factor (PAF) has recently been shown to be a potent ulcerogenic agent in the stomach and intestinal mucosa. Its extract mechanism of action is not yet known although histological studies suggest that vasocongestion is an important feature of PAF-induced damage. We have therefore studied the activity of various agents with different modes of action toward PAF-induced gastrointestinal lesions in the rat (PAF 2 micrograms/kg i.v.; macroscopic lesions of tissue scored 20 min later; arbitrary scale from 0 to 4). Drugs were administered either i.m., s.c. (5 min) or orally (30 min) before PAF injection. PAF-induced gastric lesions were strongly inhibited by the natural PAF-antagonist BN 52021 as well as by atropine sulphate and cimetidine which implicates cholinergic stimulation in the ulcerogenic activity of PAF. The somatostatin analog BIM 23014 was also very potent against PAF, perhaps by reducing the parasympathetic stimulation in the gastric wall as described for somatostatin. Allopurinol, which is a free radical scavenger also almost totally inhibited PAF-induced gastric damage, suggesting that neutrophils are involved in the mucosal lesions. The considerable inhibition of the gastric effects of PAF found in neutrophil-depleted animal supports this hypothesis. Theophylline and disodium cromoglycate, mast cell stabilizing drugs which were also active in our model, could act by protecting mast cell degranulation induced by free radicals released from activated neutrophils. A multifunctional process seems to determine the mucosal gastric damage induced by PAF, but parasympathetic stimulation and neutrophil activation play a major role in this pathology.

Role of platelet-activating factor (PAF) in the ovoimplantation in the rat: effect of the specific PAF-acether antagonist, BN 52021.

The role of PAF (platelet-activating factor) in early pregnancy has been recently postulated. Indeed, platelet count is markedly reduced immediately prior to and returns to normal following ovoimplantation. Using a pharmacological approach, we therefore further investigated the possible involvement of PAF in ovoimplantation. BN 52021 (10 nmol), a PAF antagonist, was administered after fecondation in the lumen of the left uterine horn. A group of animals was injected with the vehicle alone. The animals were sacrificed 1 week latter and the number of implanted embryos in the treated horn and in the untreated contralateral one was assessed. When injected on day 4 of pregnancy, the PAF antagonist, BN 52021, inhibited in a dose-dependent fashion ovoimplantation suggesting a role for this lipid mediator in this process. Total inhibition of ovoimplantation was observed in the horns treated with indomethacin, NDGA or BW 755 C. In addition, a significant inhibition of ovoimplantation was also produced by the lipoxygenase inhibitor, EP 10045 (10nmol). Since both PAF and leukotrienes trigger the generation of prostaglandins in various tissues, our results indicate that these two lipid mediators may be implicated in early stages of the inflammatory reaction accompanying ovoimplantation and may contribute to the local generation of cyclooxygenase metabolites.

Inhibition of rat endotoxin-induced lethality by BN 52021 and BN 52063, compounds with PAF-acether antagonistic effect and protease-inhibitory activity.

Since proteolytic enzymes play a key role in endotoxaemia and anaphylaxis, diseases in which PAF-acether may be involved, we have investigated the activity of BN 52021 and BN 52063, two potent and specific PAF-acether antagonists, on plasma protease activity in the rat. After oral administration, both drugs dose-dependently decreased plasma trypsin-like activity (PTLA) although they did not show any inhibitory effect in vitro. PAF-acether and endotoxin injected into rats increased PTLA, the increase with endotoxin appearing more slowly but to a higher extent than with PAF-acether. Inhibition of the endotoxin-induced increase in PTLA was obtained with BN 52021, BN 52063 and dexamethasone, whereas aprotinin was ineffective. Since BN 52021 and BN 52063 reduced also the endotoxin-induced lethality in the rat, their antiprotease activity may be a consequence of their PAF-antagonistic effect. Further studies will be required with other PAF antagonists to assess fully this assumption.

[Mechanism of action of Ginkgo biloba extract in experimental cerebral edema]. / Mécanismes d'action de l'extrait de Ginkgo biloba sur l'oedème cérébral expérimental.

Oedema is one of the major complication of cerebral ischaemia being at the same time a consequence and an aggravating factor. Its first phase is intracellular and cytotoxic, with breakdown of ionic pumps through loss of energy, resulting in a whole sequence of ionic perturbations characterized by loss of intracellular K+ and accumulation of water and Na+, Cl-, and Ca2+ ions in the cells of the ischaemic zone. The second phase, termed vasogenic, applies to the accumulation of lactates, inorganic phosphates and free polyunsaturated fatty acids and in particular, arachidonic acid. This last compound is responsible for the production of membrane "aggressors", amongst which free radicals play an important rôle. Ginkgo biloba extract limits the formation of cerebral oedema and suppresses its neurological consequences, whether the oedema is of cytotoxic (triethyltin) or vasogenic (unilateral traumatic oedema) origin. Several membrane mechanisms could be implicated in the protective action manifested by Ginkgo biloba extract against cerebral oedema.

The relative role of PAF-acether and icosanoids in septic shock.

Endotoxemia and gram negative sepsis remain a clinically important problem since mortality rate is still high in these diseases. Recently, the participation of some new potential mediators in this pathology is beginning to be demonstrated but the results obtained on animal models with specific inhibitors are contradictory. In order to clarify the pathological importance of icosanoids and PAF-acether in the septicemic process, we investigated the effects of indomethacin (IND) a cyclooxygenase inhibitor, NDGA and EP 10045 two lipoxygenase inhibitors, dexamethasone (DXM) a phospholipase A2 inhibitor and BN 52021 a PAF-acether receptor antagonist, on the Salmonella enteritidis-induced endotoxic shock (E.S.) in the rat. Injected subcutaneously 15 min before the test, NDGA, EP 10045 and IND were moderately effective when DXM completely prevented the endotoxin lethality. BN 52021 decreased the death rate in a dose-related manner and exerted at a non-active dose a synergistic effect on IND treatment. Furthermore, given orally 1 hour before endotoxin, it provided a potent protective effect. Our results seem to confirm that PAF-acether exerted alone, or in conjunction with products of the cyclooxygenase pathway, a key role in E.S. when LTs seem to play a role of minor importance.

In vivo inhibition of plasma protein leakage and Salmonella enteritidis-induced mortality in the rat by a specific paf-acether antagonist: BN 52021.

The effects of BN 52021, a new specific paf-acether receptor antagonist and the total Ginkgo Biloba extract (GBE 761) from which this product was isolated, were studied in the rat on paf-acether-induced permeability and cell number changes and on endotoxin-induced lethality. Their activities were compared to those of cyclooxygenase, 5-lipoxygenase and phospholipase A2 inhibitors. BN 52021 given s.c. or orally exerted a dose-related inhibition of paf-acether deleterious effects as well as of endotoxin lethality whereas the other drugs tested were poorly effective. These results strongly suggest paf-acether involvement in endotoxic and septic shock.

[Comparative effects of an extract of Ginkgo biloba and chlorpromazine on the in vitro osmotic fragility of rat erythrocytes (author's transl)]. / Comparison des effets d'un extrait de Ginkgo biloba et de la chlorpromazine sur la fragilité osmotique, in vitro, d'érythrocytes de rat.

The effects of different concentrations of an extract of Ginkgo biloba (Gb) and of chlorpromazine (CPZ) on the osmotic lysis of rat erythrocytes (produced by dilution of the incubation medium by 30%-70%) were compared in vitro. The erythrocytes were incubated together with Gb or Cpz at the time of the hemolytic reaction at 25 degrees or 37 degrees C in either a simple phosphate buffer or in a more complete buffer containing inorganic salts at physiological concentrations. CPZ produced a dose-dependent increase in the membrane resistance, the maximum effect occurring at 10(-4) M regardless of the experimental conditions used. Gb also increased membrane resistance, but to a lesser extent than CPZ. In addition, Gb was more effective under conditions which increased erythrocyte membrane fragility; i.e., 37 degrees C, simple phosphate buffer. The mechanism of action of Gb seems to differ from that of CPZ. The activity of CPZ (as a membrane stabilizer) is, in part, due to its penetration into the membrane phospholipid layer. Gb might act in a similar manner, but could also modify Na+ transport across the cell membrane by an action on adrenergic receptors, or could stimulate Na+, K+-ATP-ase activity, as has been described for norepinephrine. As Gb contains many molecular constituents: its action on the membrane is likely to be quite complex; but this effect could be associate with its vascular therapeutic action.