Children with atopic histories exhibit impaired lipopolysaccharide-induced Toll-like receptor-4 signalling in peripheral monocytes

BACKGROUND

The hygiene hypothesis states that early exposure to bacterial products such as lipopolysaccharide (LPS) may be protective against the development of allergic diseases. Whether atopic disease affects the ability of immune cells to respond to LPS is unclear. Our laboratory has demonstrated previously that children express high levels of Toll-like receptor (TLR)-4 on CD4(+) cells in nasal mucosa.

OBJECTIVE

To determine if children with a history of allergic disease have impaired responses to LPS on circulating CD4(+) leucocytes.

METHODS

Peripheral blood mononuclear cells from children (aged 2-18) and adults with or without a history of atopic conditions were cultured with/without IL-4 or LPS for up to 24 h. Expression of surface TLR-4, CD14, CD4, CD3, as well as of intracellular phosphorylated (p42/p44) ERK and p38 mitogen-activated protein kinase (MAPK) were assessed by flow cytometry.

RESULTS

A history of atopy in children was associated with impaired LPS-induced TLR-4-dependent phosphorylation of (p42/44) ERK and p38 MAPK by CD4(+) monocytes. Decreased LPS signalling was reproduced by pre-incubation of control cells with recombinant IL-4. LPS stimulation also decreased TLR-4 expression on monocytes from children without atopic histories but not from atopic subjects. CD4(+) T lymphocytes showed limited LPS responsiveness, regardless of atopic status. In contrast with non-atopic children, TLR-4 expression on monocytes of children with atopic histories decreased as a function of age.

CONCLUSIONS

This study provides evidence for defective LPS recognition on circulating CD4(+) leucocytes of subjects with atopic histories compared with those from non-atopic children. CD4(+) TLR4(+) monocytes from children with atopic histories failed to phosphorylate MAPKs. Our results suggest that a history of atopic disease is associated with impaired TLR-4-mediated innate immune function compared with non-atopic children.

Intravenous immunoglobulin attenuates airway hyperresponsiveness in a murine model of allergic asthma

BACKGROUND

Intravenous immunoglobulin (IVIG) has potent anti-inflammatory and immune-modulating properties. IVIG has been utilized as a steroid-sparing agent in severe asthma, but the results of clinical trials have been conflicting.

OBJECTIVE

To determine whether IVIG is able to attenuate bronchial reactivity, pulmonary inflammation and T cell function using a murine model of allergic airways disease.

METHODS

BALB/c or C57BL/6 mice were sensitized to ovalbumin (OVA) or a phosphate-buffered saline control using local nasal sensitization, and then received five intranasal challenges on days 28-32 before sacrifice. Mice were treated intraperitoneally with either IVIG (1-2 g/kg) or equivalent human serum albumin 24 h before the first OVA challenge. Bronchial reactivity to methacholine was examined using the FlexiVent small animal ventilator. We evaluated pulmonary histology, mRNA from lung digests for T-helper type 2 (Th2)-related genes and bronchoalveolar lavage for cell counts and cytokines. Splenocytes were utilized to study OVA-induced cell proliferation, cytokine production and dendritic cell maturation.

RESULTS

IVIG markedly attenuated the perivascular and peribronchial pulmonary inflammation, and decreased bronchial hyperresponsiveness to methacholine. IVIG treatment of splenocytes from sensitized animals diminished cellular proliferation to OVA, whereas IVIG treatment in vivo markedly attenuated OVA-driven splenocyte proliferation. This is accompanied by diminished IL-13 and TNF-α levels in splenocyte culture, decreased expression of Jagged-1, increased Delta-4 and decreased GATA-3 mRNA levels, signs that IVIG has suppressed the expected Th2 response that accompanies repeated allergen exposure. Increased regulatory T cells were found in draining pulmonary lymph nodes in IVIG-treated mice but not in controls.

CONCLUSIONS AND CLINICAL RELEVANCE

IVIG was effective in ameliorating allergic airway disease in our model. IVIG may be a promising adjunct therapy requiring further study for patients with severe asthma.

B lymphocytes in inflammatory airway diseases

B lymphocytes are key players in all facets of adaptive immune responses and are responsible for the production of IgE antibodies, initiators of allergic hypersensitivity reactions. Recent evidence indicates that B cells may be a crucial player in allergic and inflammatory airway pathology, directly populating upper and lower airway tissues. This review examines human and animal studies that directly demonstrated the presence of B lymphocytes in airway tissues and elaborates on their function as antibody-secreting cells, antigen-presenting cells and producers of inflammatory and regulatory cytokines. B lymphocytes appear to contribute to multiple facets of immune homeostasis in inflammatory diseases of the upper and lower airways.

Cardiopulmonary bypass induces significant platelet activation in children undergoing open-heart surgery

BACKGROUND AND OBJECTIVES

To evaluate the effects of cardiopulmonary bypass (CPB) on platelet function in children undergoing open-heart surgery.

METHODS

Data from 16 consecutive children undergoing cardiac surgery with CPB were prospectively collected. Blood samples of 10 mL were collected via the central venous line immediately before and after CPB for CD62 measurements by flow cytometry.

RESULTS

Ten children had acyanotic heart disease (median age 3 yr, range 1.8-14) and six had a cyanotic defect (median age 4yr, range 2-14). The platelet count decreased significantly with CPB in both groups: from 163.5 (130-201) to 93.5 (57-186) x 10(3) microL(-1) in acyanotic children and from 139.5 (77-212) to 75 (43-99) x 10(3) microL(-1) in cyanotic children (P < 0.0001). The percentage of activated platelets was significantly lower in acyanotic children at baseline: 1% (0-23%) vs. 5% (3-8%) (P = 0.07). CPB increased the percentage of activated platelets significantly in both groups: post-bypass the values were 10% (range 1-17%) in acyanotic children and 7% (range 1-30%) in cyanotic children (P = 0.03). The increase in the percentage of activated platelets did not differ between the two study groups (P = 0.11).

CONCLUSION

CPB induces significant platelet activation in children undergoing open-heart surgery.

Activation of the renin-angiotensin system contributes significantly to the pathophysiology of oliguria in patients undergoing posterior spinal fusion

BACKGROUND AND OBJECTIVE

This study was undertaken to investigate the role played by antidiuretic hormone (ADH), the renin-angiotensin system and atrial natriuretic factor (ANF) in the oliguria in patients undergoing spinal fusion.

METHODS

Sixteen patients undergoing posterior spinal fusion using isoflurane and fentanyl (n = 8) or sufentanil (n = 8) had renin, aldosterone, ADH and ANF measurements.

RESULTS

Compared to the non-oliguric patients, the oliguric patients had a higher number of fused vertebrae 10.5 +/- 1.3 vs. 9.0 +/- 0.5 (P = 0.01) and higher renin values at 12h (3.3 +/- 3.2 vs. 0.7 +/- 0.6 ng L(-1) s(-1), P = 0.04). Hormonal values that had a significant correlation with intraoperative diuresis were: renin at 0.5 h (r2 = 0.26, P = 0.04), aldosterone at 0.5 h (r2 = 0.30, P = 0.03) and ANF at 0.5 h (r2 = 0.32, P = 0.02). Those that had a significant correlation with the mean postoperative diuresis were: renin at 6 h (r2 = 0.29, P = 0.03), 8h (r2 = 0.26, P = 0.04) and 12h (r2 = 0.31, P = 0.03), aldosterone at 6h (r2 = 0.54, P = 0.001), 8h (r2 = 0.40, P = 0.01) and 12h (r2 = 0.32, P = 0.03), ADH at 24h (r2 = 0.38, P = 0.01) and ANF at 6h (r2 = 0.26, P = 0.045). Using stepwise regression, excluding hormonal values, only two continuous variables had a significant correlation with the mean postoperative diuresis: the number of fused vertebrae (P = 0.02) and the length of surgery (P = 0.02).

CONCLUSION

Activation of the renin-angiotensin system is the major cause of the early intraoperative oliguria. ADH and the renin-angiotensin system are both involved in the pathophysiology of postoperative oliguria in patients undergoing spinal fusion.

Méta-analyse : intérêt du neurostimulateur dans l'amélioration du taux de succès du bloc axillaire

OBJECTIVE

To evaluate the effectiveness of the neurostimulator to improve the success rate of a brachial plexus blockade by the axillary approach.

STUDY DESIGN

Metaanalysis.

METHODS

Ten prospective randomized studies comparing a neurostimulating technique (NST) of brachial plexus blockade performed by the axillary approach to another technique were kept for analysis. A successful block was defined as blockade of the four following nerves: radial, median, ulnar and musculocutaneous. Data were entered on an intention to treat basis and were analyzed with a random model. A p<0.05 was considered significant.

RESULTS

Data were heterogenous (p < 0.001) and the Cochran-Mantel-Haenzel test showed that the neurostimulator does not improve the success rate of brachial plexus blocks performed by the axillary approach when all available studies are considered as a whole (p = 1). For the subgroup of studies where four nerves were stimulated however, the NST decreases the incidence of failed block by 25% (95% CI = 7-42%) (p < 0.0001). There were 12 patients with systemic signs of local anesthetics toxicity when a NST was used compared to 28 when it was not (p = 0.04), relative risk of 0.7 (95% CI= 0.6-0.8).

CONCLUSION

This study shows that the neurostimulator improves the success rate of brachial plexus blocks performed by the axillary approach only when three nerves or more are stimulated and its use decreases the incidence of systemic local anaesthetics toxicity.

Contextual modulation of synchronization to random dots in the cat visual cortex

Synchronization of neuronal activity has been proposed as a binding mechanism for integration of image properties into one coherent percept. In the present study, we investigated the contextual modulation of synchronization to random dot patterns. Coherent motion of random dots evoked well synchronized responses in area 17 of anaesthetized cats when the stimulus was presented in the compound receptive field of recorded sites. Gradually changing the directional coherence of random dots in the surround while maintaining fully coherent motion of the stimulus in the receptive field significantly suppressed synchronization of neuronal activity for some stimulus conditions. However, usually one or two peaks of increased synchronization were found in the surround coherence tuning curves with low (8-12%) and/or moderate (25-50%) coherence in the surround. At the population level, synchronization was significantly depressed with incoherent motion in the receptive field and when both the surround and the receptive field were jointly stimulated with 0% coherence. The intriguing finding was the discovery of two distinct groups of cells with opposite synchronization changes dependent on the presence or absence of significant synchronization in their spontaneous activity. The latter group of neurons showed peaks of increased synchronization with lower surround coherence, thus probably being more sensitive to the direction of the surround motion. Overall, our findings support the notion that binding of stimulus properties can be achieved by synchronized activity of cortical cells. However, our findings go further than the original hypothesis of feature binding by synchrony to show that synchronization of cortical activity may be directly related to the decision making processes, which in turn are related to the threshold of perception of coherent motion.

Haemostatic disorders during liver transplantation

Profound and complex coagulation disorders are encountered during liver transplantation. They include preoperative coagulation disorders related to the liver disease and haemostatic changes related to the procedure itself. They commonly lead to increased intraoperative bleeding, especially due to increased fibrinolysis, the contribution of which can be demonstrated by the relative efficacy of antifibrinolytics. Given the multifactorial nature of bleeding in liver transplantation, preoperative coagulation tests cannot predict blood loss even if some statistical relationship is occasionally found. Preoperative correction of coagulation defects has not been shown to be effective in reducing intraoperative bleeding. Throughout the procedure, a rapid and sensitive method for monitoring coagulation is necessary in order to guide the rational use of blood components and pharmacological agents. The usefulness of such a method to assist management of blood loss or blood component requirements is poorly documented and controversial.

[The forgotten actors]

Within the Regional Plans for the Organization of Services, Quebec's mental health reform has tried to redistribute power and influence to mutual aid groups for consumers and their families. However, it has failed to provide them with the financial resources that would allow them to exert that new power. The groups don't have enough personnel to fill the decision-making positions accorded to them under the regional plans while, at the same time, continuing to provide services to consumers. Real partnership requires equality in resources. Social integration being the product of an interaction between consumers and citizens, citizens are the forgotten actors of the interaction. We fail to support them when they are faced with behaviours that they find strange and disturbing. Attitudinal and behavioural changes are interrelated and concomitant; that is, the transformation of citizens' prejudice into acceptance is helped by consumers' efforts to adopt less offensive behaviours.

Cloning, expression, and up-regulation of inducible rat prostaglandin e synthase during lipopolysaccharide-induced pyresis and adjuvant-induced arthritis

We have cloned and expressed the inducible form of prostaglandin (PG) E synthase from rat and characterized its regulation of expression in several tissues after in vivo lipopoylsaccharide (LPS) challenge. The rat PGE synthase is 80% identical to the human enzyme at the amino acid level and catalyzes the conversion of PGH(2) to PGE(2) when overexpressed in Chinese hamster ovary K1 (CHO-K1) cells. PGE synthase activity was measured using [(3)H]PGH(2) as substrate and stannous chloride to terminate the reaction and convert all unreacted unstable PGH(2) to PGF(2alpha) before high pressure liquid chromatography analysis. We assessed the induction of PGE synthase in tissues from Harlan Sprague-Dawley rats after LPS-induced pyresis in vivo. Rat PGE synthase was up-regulated at the mRNA level in lung, colon, brain, heart, testis, spleen, and seminal vesicles. Cyclooxygenase (COX)-2 and interleukin 1beta were also up-regulated in these tissues, although to different extents than PGE synthase. PGE synthase and COX-2 were also up-regulated to the greatest extent in a rat model of adjuvant-induced arthritis. The RNA induction of PGE synthase in lung and the adjuvant-treated paw correlated with a 3.8- and 16-fold induction of protein seen in these tissues by immunoblot analysis. Because PGE synthase is a member of the membrane-associated proteins in eicosanoid and glutathione metabolism (MAPEG) family, of which leukotriene (LT) C(4) synthase and 5-lipoxygenase-activating protein are also members, we tested the effect of LTC(4) and the 5-lipoxygenase-activating protein inhibitor MK-886 on PGE synthase activity. LTC(4) and MK-886 were found to inhibit the activity with IC(50) values of 1.2 and 3.2 microm, respectively. The results demonstrate that PGE synthase is up-regulated in vivo after LPS or adjuvant administration and suggest that this is a key enzyme involved in the formation of PGE(2) in COX-2-mediated inflammatory and pyretic responses.

Etoricoxib (MK-0663): preclinical profile and comparison with other agents that selectively inhibit cyclooxygenase-2

We report here the preclinical profile of etoricoxib (MK-0663) [5-chloro-2-(6-methylpyridin-3-yl)-3-(4-methylsulfonylphenyl) pyridine], a novel orally active agent that selectively inhibits cyclooxygenase-2 (COX-2), that has been developed for high selectivity in vitro using whole blood assays and sensitive COX-1 enzyme assays at low substrate concentration. Etoricoxib selectively inhibited COX-2 in human whole blood assays in vitro, with an IC(50) value of 1.1 +/- 0.1 microM for COX-2 (LPS-induced prostaglandin E2 synthesis), compared with an IC(50) value of 116 +/- 8 microM for COX-1 (serum thromboxane B2 generation after clotting of the blood). Using the ratio of IC(50) values (COX-1/COX-2), the selectivity ratio for the inhibition of COX-2 by etoricoxib in the human whole blood assay was 106, compared with values of 35, 30, 7.6, 7.3, 2.4, and 2.0 for rofecoxib, valdecoxib, celecoxib, nimesulide, etodolac, and meloxicam, respectively. Etoricoxib did not inhibit platelet or human recombinant COX-1 under most assay conditions (IC(50) > 100 microM). In a highly sensitive assay for COX-1 with U937 microsomes where the arachidonic acid concentration was lowered to 0.1 microM, IC(50) values of 12, 2, 0.25, and 0.05 microM were obtained for etoricoxib, rofecoxib, valdecoxib, and celecoxib, respectively. These differences in potency were in agreement with the dissociation constants (K(i)) for binding to COX-1 as estimated from an assay based on the ability of the compounds to delay the time-dependent inhibition by indomethacin. Etoricoxib was a potent inhibitor in models of carrageenan-induced paw edema (ID(50) = 0.64 mg/kg), carrageenan-induced paw hyperalgesia (ID(50) = 0.34 mg/kg), LPS-induced pyresis (ID(50) = 0.88 mg/kg), and adjuvant-induced arthritis (ID(50) = 0.6 mg/kg/day) in rats, without effects on gastrointestinal permeability up to a dose of 200 mg/kg/day for 10 days. In squirrel monkeys, etoricoxib reversed LPS-induced pyresis by 81% within 2 h of administration at a dose of 3 mg/kg and showed no effect in a fecal 51Cr excretion model of gastropathy at 100 mg/kg/day for 5 days, in contrast to lower doses of diclofenac or naproxen. In summary, etoricoxib represents a novel agent that selectively inhibits COX-2 with 106-fold selectivity in human whole blood assays in vitro and with the lowest potency of inhibition of COX-1 compared with other reported selective agents.

Potency and selectivity of inhibition of cathepsin K, L and S by their respective propeptides

The prodomains of several cysteine proteases of the papain family have been shown to be potent inhibitors of their parent enzymes. An increased interest in cysteine proteases inhibitors has been generated with potential therapeutic targets such as cathepsin K for osteoporosis and cathepsin S for immune modulation. The propeptides of cathepsin S, L and K were expressed as glutathione S-transferase-fusion proteins in Escherichia coli. The proteins were purified on glutathione affinity columns and the glutathione S-transferase was removed by thrombin cleavage. All three propeptides were tested for inhibitor potency and found to be selective within the cathepsin L subfamily (cathepsins K, L and S) compared with cathepsin B or papain. Inhibition of cathepsin K by either procathepsin K, L or S was time-dependent and occurred by an apparent one-step mechanism. The cathepsin K propeptide had a Ki of 3.6-6.3 nM for each of the three cathepsins K, L and S. The cathepsin L propeptide was at least a 240-fold selective inhibitor of cathepsin K (Ki = 0.27 nM) and cathepsin L (Ki = 0.12 nM) compared with cathepsin S (Ki = 65 nM). Interestingly, the cathepsin S propeptide was more selective for inhibition of cathepsin L (Ki = 0.46 nM) than cathepsin S (Ki = 7.6 nM) itself or cathepsin K (Ki = 7.0 nM). This is in sharp contrast to previously published data demonstrating that the cathepsin S propeptide is equipotent for inhibition of human cathepsin S and rat and paramecium cathepsin L [Maubach, G., Schilling, K., Rommerskirch, W., Wenz, I., Schultz, J. E., Weber, E. & Wiederanders, B. (1997), Eur J. Biochem. 250, 745-750]. These results demonstrate that limited selectivity of inhibition can be measured for the procathepsins K, L and S vs. the parent enzymes, but selective inhibition vs. cathepsin B and papain was obtained.

Synthesis and biological evaluation of 3-heteroaryloxy-4-phenyl-2(5H)-furanones as selective COX-2 inhibitors

A series of 3-heteroaryloxy4-phenyl-2-5H)-furanones were prepared and evaluated for their potency and selectivity as COX-2 inhibitors. This led to the identification of L-778,736 as a potent, orally active and selective inhibitor of the COX-2 enzyme.

A new structural variation on the methanesulfonylphenyl class of selective cyclooxygenase-2 inhibitors

By inserting an oxygen link between the 3-fluorophenyl and the lactone ring of 5,5-dimethyl-3-(3fluorophenyl)-4-(4-methanesulfonylphenyl)-2 (5H)-furanone 1 (DFU), analogs with enhanced in vitro COX-2 inhibitory potency as well as in vivo potency in models of inflammation were obtained.

Substituted indoles as potent and orally active 5-lipoxygenase activating protein (FLAP) inhibitors

This paper reports on the SAR investigation of inhibitors of 5-lipoxygenase activating protein (FLAP) based on MK-0591. Emphasis was made on modifications to the nature of the link between the indole and the quinoline moieties, to the substitution pattern around the two heterocycles and to possible replacements of the quinoline moiety. Lead optimization culminated in (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(pyridin-2-ylmethoxy)-ind ol-2-yl]-2,2-dimethylpropanoic acid (18k), as a potent inhibitor of leukotriene biosynthesis that is well absorbed and active in functional models.

SAR in the alkoxy lactone series: the discovery of DFP, a potent and orally active COX-2 inhibitor

Extensive SAR has been established in the alkoxy lactone series and this has lead to the discovery of DFP (5,5-dimethyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanon e), a potent COX-2 inhibitor exhibiting in vivo efficacy in all models studied.

Cloning and expression of rhesus monkey cathepsin K

Cathepsin K is a cysteine protease involved in degradation of human type I collagen and plays a primary role in bone resorption. We have cloned rhesus monkey cathepsin K by reverse transcriptase-polymerase chain reaction (RT-PCR) from rhesus ovary poly A+ RNA. The sequence for the rhesus enzyme is 98% identical to that of the human with 100% identity within the mature active form of cathepsin K. Rhesus monkey cathepsin K was transiently expressed in Chinese hamster ovary (CHO) cells and found to be secreted as the proenzyme in the culture media and 50% activated to the mature form intracellularly. The substrate specificity preference of aminomethylcoumarin and rhodamine peptide substrates was Leu > Phe > Pro in the P2 position when tested with constant arginine at P1. The enzyme activity expressed in CHO cell extracts was sensitive to inhibition by E-64 and cystatin with IC50s of 3.5 nmol/L and 13 ng/mL, respectively. The apparent second order rate constants of inactivation by E-64 were 66,000 M(-1) s(-1) and 130,000 M(-1) s(-1) for the recombinantly expressed rhesus monkey and human cathepsin K, respectively. The high similarity between the sequences and the kinetic properties of rhesus monkey and human cathepsin K establishes this monkey species as a suitable animal model for development of novel cathepsin K inhibitors as antiresorptive agents.

Rofecoxib [Vioxx, MK-0966; 4-(4'-methylsulfonylphenyl)-3-phenyl-2-(5H)-furanone]: a potent and orally active cyclooxygenase-2 inhibitor. Pharmacological and biochemical profiles

The discoveries that cyclooxygenase (COX)-2 is an inducible form of COX involved in inflammation and that COX-1 is the major isoform responsible for the production of prostaglandins (PGs) in the gastrointestinal tract have provided a rationale for the development of specific COX-2 inhibitors as a new class of anti-inflammatory agents with improved gastrointestinal tolerability. In the present study, the preclinical pharmacological and biochemical profiles of rofecoxib [Vioxx, also known as MK-0966, 4-(4'-methylsulfonylphenyl)-3-phenyl-2-(5H)-furanone], an orally active COX-2 inhibitor, are described. Rofecoxib is a potent inhibitor of the COX-2-dependent production of PGE(2) in human osteosarcoma cells (IC(50) = 26 +/- 10 nM) and Chinese hamster ovary cells expressing human COX-2 (IC(50) = 18 +/- 7 nM) with a 1000-fold selectivity for the inhibition of COX-2 compared with the inhibition of COX-1 activity (IC(50) > 50 microM in U937 cells and IC(50) > 15 microM in Chinese hamster ovary cells expressing human COX-1). Rofecoxib is a time-dependent inhibitor of purified human recombinant COX-2 (IC(50) = 0.34 microM) but caused inhibition of purified human COX-1 in a non-time-dependent manner that could only be observed at a very low substrate concentration (IC(50) = 26 microM at 0.1 microM arachidonic acid concentration). In an in vitro human whole blood assay, rofecoxib selectively inhibited lipopolysaccharide-induced, COX-2-derived PGE(2) synthesis with an IC(50) value of 0.53 +/- 0.02 microM compared with an IC(50) value of 18.8 +/- 0.9 microM for the inhibition of COX-1-derived thromboxane B(2) synthesis after blood coagulation. Using the ratio of the COX-1 IC(50) values over the COX-2 IC(50) values in the human whole blood assay, selectivity ratios for the inhibition of COX-2 of 36, 6.6, 2, 3, and 0.4 were obtained for rofecoxib, celecoxib, meloxicam, diclofenac, and indomethacin, respectively. In several in vivo rodent models, rofecoxib is a potent inhibitor of carrageenan-induced paw edema (ID(50) = 1.5 mg/kg), carrageenan-induced paw hyperalgesia (ID(50) = 1.0 mg/kg), lipopolysaccharide-induced pyresis (ID(50) = 0.24 mg/kg), and adjuvant-induced arthritis (ID(50) = 0.74 mg/kg/day). Rofecoxib also has a protective effect on adjuvant-induced destruction of cartilage and bone structures in rats. In a (51)Cr excretion assay for detection of gastrointestinal integrity in either rats or squirrel monkeys, rofecoxib has no effect at doses up to 200 mg/kg/day for 5 days. Rofecoxib is a novel COX-2 inhibitor with a biochemical and pharmacological profile clearly distinct from that of current nonsteroidal anti-inflammatory drugs and represents a new therapeutic class of anti-inflammatory agents for the treatment of the symptoms of osteoarthritis and rheumatoid arthritis with improved gastrointestinal tolerability.

The discovery of rofecoxib, [MK 966, Vioxx, 4-(4'-methylsulfonylphenyl)-3-phenyl-2(5H)-furanone], an orally active cyclooxygenase-2-inhibitor

The development of a COX-2 inhibitor rofecoxib (MK 966, Vioxx) is described. It is essentially equipotent to indomethacin both in vitro and in vivo but without the ulcerogenic side effect due to COX-1 inhibition.

2,3-Diarylcyclopentenones as orally active, highly selective cyclooxygenase-2 inhibitors

Cyclopentenones containing a 4-(methylsulfonyl)phenyl group in the 3-position and a phenyl ring in the 2-position are selective inhibitors of cyclooxygenase-2 (COX-2). The selectivity for COX-2 over COX-1 is dramatically improved by substituting the 2-phenyl group with halogens in the meta position or by replacing the phenyl ring with a 2- or 3-pyridyl ring. Thus the 3,5-difluorophenyl derivative 7 (L-776,967) and the 3-pyridyl derivative 13 (L-784,506) are particularly interesting as potential antiinflammatory agents with reduced side-effect profiles. Both exhibit good oral bioavailability and are potent in standard models of pain, fever, and inflammation yet have a much reduced effect on the GI integrity of rats compared to standard nonsteroidal antiflammatory drugs.

[Polytrauma and hemostatic anomalies]

OBJECTIVE

Polytraumatized patients present with defects of haemostasis that manifest clinically either by haemorrhage and/or thrombosis. During the initial, as well as during the later phases of treatment, clinicians should take into account the most recent developments in the understanding, in the evaluation of the risk, and in the prevention of haemorrhagic and thrombotic complications.

SOURCE

A group of experts, convened by the "Groupe d'intérêt en hémostase périopératoire" (Perioperative Haemostasis Interest Group) during the Annual Meeting of the Association of Anaesthetists of Quebec, held a symposium to review and integrate recent developments on haemostatic complications associated with trauma.

MAIN FINDINGS

The normal haemostatic balance is strongly compromised by trauma and shock. The percentage of patients with a coagulopathy and surgically uncontrollable haemorrhage varies between 18 and 40%. Abnormal coagulation after trauma is of multifactorial origin. Coagulopathy secondary to haemodilution is no longer considered the main cause of haemorrhage. Disseminated intravascular coagulation (DIC) is often manifest in the traumatic context. One out of every three polytraumatized patient will develop a deep vein thrombosis despite the preventive measures available at present. Clinical or laboratory detection of venous thrombosis either lacks sensitivity (physical examination or ultrasonography), or cannot be performed serially (phlebography).

CONCLUSIONS

Prevention and treatment of disorders of haemostasis relies upon the rapid and effective treatment of shock associated with trauma. Prevention of thromboembolic complications is paramount, taking into account the evolving balance between the risk of haemorrhage and the risk of thrombosis.

Clinical pharmacokinetics of neuromuscular relaxants in pregnancy

Despite an increased in bodyweight, plasma volume by 45% and blood volume by 35% that might influence the volume of distribution of polar drugs, the apparent volume of distribution at steady state (Vss), volume of distribution (Vd) and the apparent volume of the central compartment (Vc) of atracurium, vecuronium and pancuronium are unchanged during pregnancy. With an elimination that is independent of renal, hepatic and enzymatic functions, the clearance of atracurium is also unchanged. This is corroborated by an unchanged clinical duration of atracurium during pregnancy. The clearance of pancuronium is increased by 27% during caesarean section. This may be explained by the increased glomerular filtration rate reported in pregnant women. The clinical duration of vecuronium in term and postpartum women is twice that reported in nonpregnant women. On the other hand, an increase in the clearance clearance of vecuronium during cesarean sections has been reported. The umbilical/maternal vein concentration ratio (UV/MV) of nondepolarising neuromuscular relaxants varies from 7 to 26% and clinical doses of these drugs may induce partial residual curarisation in neonates. Fetal concentrations of non-depolarising neuromuscular relaxants are proportional to the maternal dose injected as demonstrated for pancuronium and vecuronium. Increasing UV/MV with longer drug injection to delivery intervals have been demonstrated for drugs with a high molecular weight, such as atracurium, but not for those with a low molecular weight, such as vecuronium, while conflicting results have been reported for pancuronium. Despite decreased plasma pseudocholinesterases, the clinical duration of succinylcholine 1 mg/kg is unchanged in pregnant women, and only is slightly increased in postpartum women. On the other hand, larger doses of succinylcholine have induced prolonged apnoea and phase II block. The use of a pretreatment dose of a nondepolarising neuromuscular relaxant to decrease fasciculations and subsequent postoperative muscle pain is not only unnecessary in pregnant women but may be hazardous, since it may produce unexpected significant curarisation with respiratory distress. At clinical doses, transplacental passage of succinylcholine is insufficient to produce curarisation of neonates except in those born to mothers with abnormal plasma pseudocholinesterases. Magnesium sulfate, used in the treatment of pre-eclampsia, will enhance the blocking effects of nondepolarising neuromuscular relaxants but will have no effects on the characteristics of paralysis of succinylcholine. Histamine type 2 antagonists used to decrease the risk of aspiration during induction of anaesthesia do not influence the blocking properties of neuromuscular relaxants, while metoclopramide prolongs the block of succinylcholine.

Quinolines as potent 5-lipoxygenase inhibitors: synthesis and biological profile of L-746,530

Leukotriene biosynthesis inhibitors have potential as new therapeutic agents for asthma and inflammatory diseases. A series of novel substituted 2-cyanoquinolines have been synthesized and the structure activity relationships were evaluated with respect to their ability to inhibit the formation of leukotrienes via the 5-lipoxygenase enzyme. [1S,5R]-2-Cyano-4-(3-furyl)-7-¿3-fluoro-5-[3-(3 alpha-hydroxy-6,8-dioxabicyclo[3.2.1]-octanyl)]phenoxymethyl ¿quinoline (L-746,530) 3 represents a distinct class of inhibitors and possesses in vitro and in vivo potency comparable or superior to naphthalenic analog (L-739,010) 2.

Cloning of a complementary DNA encoding an Ambystoma mexicanum metallothionein, AmMT, and expression of the gene during early development

We have used a polymerase chain reaction strategy to isolate a metallothionein (MT) cDNA from the amphibian Ambystoma mexicanum (axolotl). This cDNA is 875-bp long and encodes a 60 amino acid protein, AmMT, typical for family 1 MTs. It contains 20 cysteine (Cys) residues that can be aligned with those of other vertebrate MTs. The overall structure of the protein is unique among vertebrates in having only two amino acid residues before the first Cys at the amino-terminal end. Northern analyses showed that AmMT is expressed throughout embryogenesis, giving rise to three mRNA species of 650, 750, and 1,600 nucleotides (nt). The 750 and 1,600 nt transcripts appear to result from differential use of polyadenylation signals, whereas the 650 nt RNA could arise from deadenylation of the 750-nt transcript. Both the 750- and 1,600-nt RNAs were presented in embryos before the mid-blastula transition (MBT). After the MBT, the 750-nt RNA was replaced by the 650-nt RNA which was gradually degraded to undetectable levels in post-neurulation embryos. Levels of the 1,600-nt transcript increased at gastrulation and reach a maximum in Stage 30 embryos. In adult animals, levels of the 750-nt RNA were high in liver and testes, and very low in lung, gut, skin, and oviducts, whereas levels of the 1,600-nt transcript were similar and moderately elevated in all tissues examined. In contrast, in Xenopus laevis, Northern analysis did not detect XIMT-A mRNA in embryos before late neurulation (Stage 24). XIMT-A mRNA levels then increased sharply in Stage 36 hatched embryos at levels similar to those found in adult livers. These results show that AmMT presents a unique expression pattern among metazoans being transcribed as two transcripts differing in the length of their 3' untranslated regions, the levels of which vary during embryogenesis and in adult tissues.

Comparison of the cyclooxygenase-1 inhibitory properties of nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors, using sensitive microsomal and platelet assays

Two forms of cyclooxygenase (COX) activity are involved in the synthesis of prostaglandins, prostacyclins, and thromboxanes in mammalian cells. There is now convincing evidence, obtained with a number of structurally distinct inhibitors, that selective COX-2 inhibitors possess anti-inflammatory effects with an improved gastrointestinal tolerability compared with conventional nonsteroidal anti-inflammatory drugs (NSAIDs) affecting both COX-1 and COX-2. As more selective COX-2 inhibitors are being developed, assays with a high degree of sensitivity to inhibition are needed to compare the relative effects of compounds on COX-1 activity. In the present report, we describe a sensitive assay for the inhibition of human COX-1 based on the production of prostaglandin E2 by microsomes from U937 cells incubated with a subsaturating concentration of arachidonic acid. More than 45 NSAIDs and selective COX-2 inhibitors were tested in this assay. IC50 values ranged from 1 nM for flunixin and flurbiprofen to about 200-500 microM for salicylate and acetaminophen. Potent and nonselective NSAIDs such as sulindac sulfide, diclofenac, and indomethacin showed IC50 values of < 20 nM. Among the compounds that have been reported to show selectivity for COX-2, the rank order of potency against COX-1 was DuP 697 > SC-58451 > celecoxib > nimesulide-meloxicam-piroxicam-NS-398-RS-57067 > SC-57666 > SC-58125 > flosulide > etodolac > L-745,337 > DFU-T-614, with IC50 values ranging from 7 nM to 17 microM. A good correlation was obtained between the IC50 values for the inhibition of microsomal COX-1 and both the inhibition of TXB2 production by Ca2+ ionophore challenged platelets and the inhibition of prostaglandin E2 production by CHO cells stably expressing human COX-1. However, the microsomal assay was more sensitive to inhibition than cell-based assays and allowed the detection of inhibitory effects on COX-1 for all NSAIDs and selective COX-2 inhibitors examined with discrimination of their potency under conditions of limited availability of arachidonic acid.

Substituted (pyridylmethoxy)naphthalenes as potent and orally active 5-lipoxygenase inhibitors; synthesis, biological profile, and pharmacokinetics of L-739,010

Dioxabicyclooctanyl naphthalenenitriles have been reported as a class of potent and nonredox 5-lipoxygenase (5-LO) inhibitors. These bicyclo derivatives were shown to be metabolically more stable than their tetrahydropyranyl counterparts but were not well orally absorbed. Replacement of the phenyl ring in the naphthalenenitrile 1 by a pyridine ring leads to the potent and orally absorbed inhibitor 3g (L-739,010, 2-cyano-4-(3-furyl)-7-[[6-[3-(3-hydroxy-6,8-dioxabicyclo[3.2.1] octanyl)]-2-pyridyl]methoxy]naphthalene). Compound 3g inhibits 5-HPETE production by human 5-LO and LTB4 biosynthesis by human PMN leukocytes and human whole blood (IC50S of 20, 1.6, and 42 nM, respectively). Derivative 3g is orally active in the rat pleurisy model (inhibition of LTB4, ED50 = 0.3 mg/kg) and in the anesthetized dog model (inhibition of ex vivo whole blood LTB4 and urinary LTE4, ED50 = 0.45 and 0.23 microgram/kg/min, respectively, i.v. infusion). In addition, 3g shows excellent functional activity against ovalbumin-induced dyspnea in rats (60% inhibition at 0.5 mg/kg, 4 h pretreatment) and Ascaris-induced bronchoconstriction in conscious sheep (50% and > 85% inhibition in early and late phases, respectively at 2.5 micrograms/kg/min, i.v. infusion) and, more particularly in the conscious antigen sensitive squirrel monkey model (53% inhibition of the increase in RL and 76% in the decrease of Cdyn, at 0.1 mg/kg, po). In rats and dogs, 3g presents excellent pharmacokinetics (estimated half-lives of 5 and 16 h, respectively) and bioavailabilities (26% and 73% when dosed as its hydrochloride salt at doses of 20 and 10 mg/kg, respectively, in methocel suspension). Based on its overall biological profile, compound 3g has been selected for preclinical animal toxicity studies.

Biochemical and pharmacological profile of a tetrasubstituted furanone as a highly selective COX-2 inhibitor

1. DFU (5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furan one) was identified as a novel orally active and highly selective cyclo-oxygenase-2 (COX-2) inhibitor. 2. In CHO cells stably transfected with human COX isozymes, DFU inhibited the arachidonic acid-dependent production of prostaglandin E2 (PGE2) with at least a 1,000 fold selectivity for COX-2 (IC50 = 41 +/- 14 nM) over COX-1 (IC50 > 50 microM). Indomethacin was a potent inhibitor of both COX-1 (IC50 = 18 +/- 3 nM) and COX-2 (IC50 = 26 +/- 6 nM) under the same assay conditions. The large increase in selectivity of DFU over indomethacin was also observed in COX-1 mediated production of thromboxane B2 (TXB2) by Ca2+ ionophore-challenged human platelets (IC50 > 50 microM and 4.1 +/- 1.7 nM, respectively). 3. DFU caused a time-dependent inhibition of purified recombinant human COX-2 with a Ki, value of 140 +/- 68 microM for the initial reversible binding to enzyme and a kappa 2 value of 0.11 +/- 0.06 s-1 for the first order rate constant for formation of a tightly bound enzyme-inhibitor complex. Comparable values of 62 +/- 26 microM and 0.06 +/- 0.01 s-1, respectively, were obtained for indomethacin. The enzyme-inhibitor complex was found to have a 1:1 stoichiometry and to dissociate only very slowly (t1/2 = 1-3 h) with recovery of intact inhibitor and active enzyme. The time-dependent inhibition by DFU was decreased by co-incubation with arachidonic acid under non-turnover conditions, consistent with reversible competitive inhibition at the COX active site. 4. Inhibition of purified recombinant human COX-1 by DFU was very weak and observed only at low concentrations of substrate (IC50 = 63 +/- 5 microM at 0.1 microM arachidonic acid). In contrast to COX-2, inhibition was time-independent and rapidly reversible. These data are consistent with a reversible competitive inhibition of COX-1. 5. DFU inhibited lipopolysaccharide (LPS)-induced PGE2 production (COX-2) in a human whole blood assay with a potency (IC50 = 0.28 +/- 0.04 microM) similar to indomethacin (IC50 = 0.68 +/- 0.17 microM). In contrast, DFU was at least 500 times less potent (IC50 > 97 microM) than indomethacin at inhibiting coagulation-induced TXB2 production (COX-1) (IC50 = 0.19 +/- 0.02 microM). 6. In a sensitive assay with U937 cell microsomes at a low arachidonic acid concentration (0.1 microM), DFU inhibited COX-1 with an IC50 value of 13 +/- 2 microM as compared to 20 +/- 1 nM for indomethacin. CGP 28238, etodolac and SC-58125 were about 10 times more potent inhibitors of COX-1 than DFU. The order of potency of various inhibitors was diclofenac > indomethacin approximately naproxen > nimesulide approximately meloxicam approximately piroxicam > NS-398 approximately SC-57666 > SC-58125 > CGP 28238 approximately etodolac > L-745,337 > DFU. 7. DFU inhibited dose-dependently both the carrageenan-induced rat paw oedema (ED50 of 1.1 mg kg-1 vs 2.0 mg kg-1 for indomethacin) and hyperalgesia (ED50 of 0.95 mg kg-1 vs 1.5 mg kg-1 for indomethacin). The compound was also effective at reversing LPS-induced pyrexia in rats (ED50 = 0.76 mg kg-1 vs 1.1 mg kg-1 for indomethacin). 8. In a sensitive model in which 51Cr faecal excretion was used to assess the integrity of the gastrointestinal tract in rats, no significant effect was detected after oral administration of DFU (100 mg kg-1, b.i.d.) for 5 days, whereas chromium leakage was observed with lower doses of diclofenac (3 mg kg-1), meloxicam (3 mg kg-1) or etodolac (10-30 mg kg-1). A 5 day administration of DFU in squirrel monkeys (100 mg kg-1) did not affect chromium leakage in contrast to diclofenac (1 mg kg-1) or naproxen (5 mg kg-1). 9. The results indicate that COX-1 inhibitory effects can be detected for all selective COX-2 inhibitors tested by use of a sensitive assay at low substrate concentration. The novel inhibitor DFU shows the lowest inhibitory potency against COX-1, a consistent high selectivity of inhibition of COX-2 over COX-1 (>300 fold) with enzyme, whole cell and whole blood assays, with no detectable loss of integrity of the gastrointestinal tract at doses >200 fold higher than efficacious doses in models of inflammation, pyresis and hyperalgesia. These results provide further evidence that prostanoids derived from COX-1 activity are not important in acute inflammatory responses and that a high therapeutic index of anti-inflammatory effect to gastropathy can be achieved with a selective COX-2 inhibitor.

Regulation of actin filament dynamics by p38 map kinase-mediated phosphorylation of heat shock protein 27

We have studied the contribution of the individual kinases of the MAP (mitogen-activated protein) kinase family, including ERK (extracellular-signal regulated kinase), JNK/SAPK (c-JUN NH2-terminal kinase/stress-activated protein kinase) and p38, to activation of the HSP27 (heat shock protein 27) kinase MAPKAP kinase-2/3 and to HSP27 phosphorylation in Chinese hamster CCL39 cells stimulated by either growth factors, cytokines or stressing agents. In vitro assays using fractionated cell extracts or immunoprecipitates indicated that only fractions containing ERK or p38, and not those containing JNK/SAPK, had the capacity to activate MAPKAP kinase-2/3. In vivo, however, it appeared that only p38 is an upstream activator of HSP27 phosphorylation after both stress or growth factor stimulation: expression of an interfering mutant of ras, which blocked the activation of ERK by both types of inducers, had no effect on HSP27 phosphorylation and p38 activation; and the cell-permeant specific inhibitor of 038, SB203580, blocked MAPKAP-kinase2/3 activation and HSP27 phosphorylation. HSP27 has been suggested to have a phosphorylation-activated homeostatic function at the actin cytoskeleton level. This raises the possibility that p38 might be directly involved in mediating actin responses to external stimuli. Accordingly, we observed that a prior activation of p38 increased the stability of the actin microfilaments in cells exposed to cytochalasin D. The effect was dependent on the expression of HSP27 and was totally annihilated by blocking the p38 activity with SB203580. The results provide strong support to the idea that activation of p38 during adverse environmental conditions serves a homeostatic function aimed at regulating actin dynamics that would otherwise be destabilized during stress. Its activation during normal agonist stimulation may constitute an additional actin signaling pathway, the importance of which depends on the level of expression of HSP27.

Mediastinal bleeding after cardiopulmonary bypass in pediatric patients

BACKGROUND

The purpose of our review was to develop simple clinical recommendations to reduce the need for allogeneic blood transfusions in children undergoing cardiac operations.

METHODS

The literature on hemostasis as it relates to children, cardiac disease in children, and pediatric heart surgery was reviewed. We also reexamined the efficacy of several strategies in this patient population: on-site monitoring of coagulation, transfusion of fresh whole blood, and administration of desmopressin, epsilon-aminocaproic acid, or aprotinin.

RESULTS

Children with heart disease may present with preoperative thrombocytopenia, reduced platelet aggregation, and a decreased level of von Willebrand factor. Infants less than 6 months of age show a significant dilution of coagulation factors and decreased platelet counts during cardiopulmonary bypass. Fresh whole blood reduces blood loss in children younger than 2 years undergoing complex operations. Desmopressin does not reduce bleeding, whereas on-site monitoring, synthetic antifibrinolytics, and aprotinin require further evaluation in pediatric cardiac surgical patients.

CONCLUSIONS

The use of fresh whole blood to reduce blood loss in children younger than 2 years undergoing complex heart operations is recommended. Therapy for excessive bleeding after cardiopulmonary bypass will vary according to the patient's age, platelet count, and activated partial thromboplastin and prothrombin times.

Dioxabicyclooctanyl naphthalenenitriles as nonredox 5-lipoxygenase inhibitors: structure-activity relationship study directed toward the improvement of metabolic stability

Naphthalenic lignan lactone 3a (L-702,539), a potent and selective 5-lipoxygenase (5-LO) inhibitor, is extensively metabolized at two different sites: the tetrahydropyran and the lactone rings. Early knowledge of the metabolic pathways triggered and directed a structure-activity relationship study aimed toward the improvement of metabolic stability in this series. The best modifications discovered, i.e., replacement of the lactone ring by a nitrile group, replacement of the tetrahydropyran ring by a 6,8-dioxabicyclo[3.2.1]octanyl moiety, and replacement of the pendant phenyl ring by a 3-furyl ring, were incorporated in a single molecule to produce inhibitor 9ac (L-708,780). Compound 9ac inhibits the oxidation of arachidonic acid to 5-hydroperoxy-eicosatetraenoic acid by 5-LO (IC50 = 190 nM) and the formation of leukotriene B4 in human polymorphonuclear leukocytes (IC50 = 3 nM) as well as in human whole blood (IC50 = 150 nM). The good inhibitory profile shown by naphthalenenitrile 9ac is accompanied by an improved resistance to oxidative metabolism. In addition, 9ac is orally active in the functional model of antigen-induced bronchoconstriction in allergic squirrel monkeys (95% inhibition at 0.1 mg/kg).

[Mutual aid as a complement to professional intervention]

This paper aims to illustrate and emphasize the relevance of Frank Riessman's futurist new paradigm for human services which proposes a restructuring that enables those who ordinarily receive help to function as providers of help. Some of the best known mutual-aid programs are briefly presented, followed by a more detailed description of pilot projects which have used the mutual-aid principle with multi-problematic clientele. Most of these pilot projects took place in the province of Québec and aimed at bridging the gap between public services and local communities by linking with informal support systems. Two specific modalities of mutual aid are discussed: pairings between clients and pairings between clients and natural helpers. The integration of mutual-aid strategies within clinical practice is not easy because of the important changes it requires of the professional both at the practical and the organizational level.

Involvement of cyclooxygenase 2 (COX-2) in intrinsic tone of isolated guinea pig trachea

Indomethacin and related nonsteroidal anti-inflammatory drugs relax prostanoid-dependent intrinsic tone of isolated guinea pig trachea by inhibiting cyclooxygenase (COX). Recently, a second isoform of COX (COX-2) was discovered, which differed from COX-1 with respect to protein structure, transcriptional regulation, and susceptibility to inhibition by pharmacological agents. It is now known that indomethacin nonselectively inhibits COX-1 and COX-2, whereas NS-398 is a selective inhibitor of COX-2. In the present study we compared the activity of a selective (NS-398) and nonselective (indomethacin) COX-2 inhibitor on intrinsic tone of isolated guinea pig trachea. NS-398 > or = indomethacin produced a reversal of intrinsic tone with a similar concentration-dependent (10 nM to 1 microM) time course (Tmax approximately 20-45 min), potency (EC50 1.7 and 5.6 nM, respectively), and maximal response. Contractions to cholinergic nerve stimulation (45 V, 0.5 ms, 0.1-32 Hz) and histamine were similarly modulated in tissues relaxed with the selective or nonselective COX-2 inhibitors. Immunoblot analyses showed that COX-2 protein synthesis was induced in both the cartilage and smooth muscle portions of the trachea during changes in intrinsic tone. These findings are consistent with pharmacological results and provide the first demonstration that prostanoid tone in isolated guinea pig trachea is dependent on COX-2 activity. The results also suggest that the activity of indomethacin in this preparation is likely related to COX-2 inhibition.

Predicting blood loss in surgery for idiopathic scoliosis

The authors attempted to determine the relative importance of factors that influence bleeding during and after spinal fusion. Data from 30 ASA I patients with idiopathic scoliosis were prospectively collected and analyzed. Intraoperative bleeding was 1971 +/- 831 ml (mean +/- SD) (61.5 +/- 27% of estimated blood volume (EBV) and correlated with the number of fused vertebrae (r = 0.66, P < 0.0001) and the duration of surgery (r = 0.46, P = 0.0105). There was no correlation between intraoperative bleeding and the Cobb curve angle (43 to 86 degrees), the mean arterial blood pressure (MAP) (63 to 86 mmHg), the central venous pressure (CVP), the quantity of epinephrine infiltrated, muscle relaxants or opioids used, nor in the type of opioids used, the minimal body temperature or whether stored or autologous blood was used. Postoperative bleeding was 1383 +/- 369 ml (43.1 +/- 11.7% of EBV) and correlated with the length of time the Hemovac drain was in place (r = 0.40, P = 0.0285) and MAP (r = 0.40, P = 0.0285). There was no correlation between postoperative and intraoperative bleeding nor in the number of fused vertebrae. Six patients had greater postoperative than intraoperative bleeding. The total bleeding (intra- plus postoperative) was 3347 +/- 920 ml (104.2 +/- 30.6 of EBV) and correlated with the number of fused vertebrae (r = 0.63, P = 0.0001) and with the duration of surgery (r = 0.42, P = 0.0208). We conclude that the number of fused vertebrae is the key factor in predicting intraoperative and total bleeding. Postoperative bleeding is considerable (up to 76.9% of EBV).(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonyl trifluoromethyl ketone, a potent inhibitor of 85-kDa phospholipase A2, blocks production of arachidonate and 12-hydroxyeicosatetraenoic acid by calcium ionophore-challenged platelets

Arachidonyl trifluoromethyl ketone (AACOCF3) is a potent and selective slow binding inhibitor of the 85-kDa cytosolic phospholipase A2 (cPLA2) (Street, I. P., Lin, H.-K., Laliberté, F., Ghomashchi, F., Wang, Z., Perrier, H., Tremblay, N. M., Huang, Z., Weech, P. K., and Gelb, M. H. (1993) Biochemistry 32, 5935-5940). AACOCF3 and a number of its structural analogues have been used to investigate the role of cPLA2 in the cellular generation of free arachidonic acid (AA) and in eicosanoid biosynthesis. AACOCF3 inhibited the release of AA from calcium ionophore-challenged U937 cells (IC50 = 8 microM, 2 x 10(6) cells ml-1) and from platelets (IC50 = 2 microM, 4 x 10(7) cells ml-1). Arachidonyl methyl ketone (AACOCH3) and AACH(OH)CF3, both of which are noninhibitory to the purified cPLA2, did not inhibit the production of AA in the ionophore-challenged cells. In addition to the release of AA, AACOCF3 also inhibited the production of 12-hydroxyeicosatetraenoic acid (12-HETE) and thromboxane B2, two of the major metabolites of AA produced by platelets. The inhibition of 12-HETE biosynthesis showed a dose dependence similar to that of AA release in ionophore-challenged platelets; however, when platelet 12-HETE production was stimulated with 10 microM AA to circumvent the PLA2-dependent step, AACOCF3 no longer inhibited the production of 12-HETE. In contrast, AACOCF3 blocked thromboxane B2 formation by both calcium ionophore- and AA-challenged platelets, indicating that the compound affects the cyclooxygenase pathway in addition to AA release. The crude cytosol and membrane fractions from platelets were assayed for calcium-dependent and calcium-independent PLA2 activities and for the susceptibility of each to inhibition by AACOCF3. At AACOCF3 concentrations as high as 10 mol %, only one of the observed PLA2 activities was inhibited by more than 25%. The AACOCF3-susceptible PLA2 (77% inhibition at 1.6 mol %) was found in the cytosolic platelet fraction and showed the functional characteristics of the cPLA2. These results suggest that the cPLA2 plays an important role in the generation of free AA for 12-HETE biosynthesis in platelets.