Two signaling mechanisms for activation of alphaM beta2 avidity in polymorphonuclear neutrophils

Circulating polymorphonuclear neutrophils (PMN) are quiescent, nonadherent cells that rapidly activate at sites of inflammation, where they develop the capacity to perform a repertoire of functions that are essential for host defense. Induction of integrin-mediated adhesion, which requires an increase in integrin avidity, is critical for the development of these effector functions. Although a variety of stimuli can activate integrins in PMN, the signaling cascades involved are unclear. Phosphatidylinositol (PI) 3-kinase has been implicated in integrin activation in a variety of cells, including PMN. In this work, we have examined activation of the PMN integrin alphaM beta2, assessing both adhesion and generation of the epitope recognized by the activation-specific antibody CBRM1/5. We have found that PI 3-kinase has a role in activation of alphaM beta2 by immune complexes, but we have found no role for it in alphaM beta2 activation by ligands for trimeric G protein-coupled receptors, including formylmethionylleucylphenylalanine (fMLP), interleukin-8, and C5a. Cytochalasin D inhibition suggests a role for the actin cytoskeleton in immune complex activation of alphaM beta2, but cytochalasin has no effect on fMLP-induced activation. Similarly, immune complex activation of the Rac/Cdc42-dependent serine/threonine kinase Pak1 is blocked by PI 3-kinase inhibitors, but fMLP-induced activation is not. These results demonstrate that two signaling pathways exist in PMN for activation of alphaM beta2. One, induced by FcgammaR ligation, is PI 3-kinase-dependent and requires the actin cytoskeleton. The second, initiated by G protein-linked receptors, is PI 3-kinase-independent and cytochalasin-insensitive. Pak1 may be in a final common pathway leading to activation of alphaM beta2.     

Prolonged administration of NT-4/5 fails to rescue most axotomized retinal ganglion cells in adult rats

The survival of axotomized RGCs was increased by intravitreal NT-4/5 given by repeated injections or osmotic minipumps, but the effects were less complete than predicted. Compared to a single injection of the neurotrophin on day 0, second injections on days 3 or 7 only sustained an additional 10-20% of the RGCs on day 10. Minipumps augmented RGC survival up to 4-fold (50%) at 2 weeks but most RGCs were lost by 1 month. Thus, specific neurotrophins can rescue many RGCs soon after injury but long-term neuronal survival may require a better understanding of changes in neurotrophin receptors and interactions with other molecules.     

Phase I study of 9-cis-retinoic acid (ALRT1057 capsules) in adults with advanced cancer

9-cis-Retinoic acid (9-cis-RA) and all-trans-RA (ATRA) are naturally occurring hormones. The nuclear receptors that mediate the effects of retinoids are the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). ATRA binds RAR with high affinity but does not bind to RXR, whereas 9-cis-RA, an isomer of ATRA, is a ligand that binds and transactivates both RARs and RXRs. The goals of this study were to determine the safety, tolerability, pharmacokinetics, and metabolic profile of 9-cis-RA in advanced cancer patients. Forty-one patients received oral 9-cis-RA (ALRT1057; Panretin capsules) at doses ranging from 5-140 mg/m2/day. Twenty-six patients were treated once daily with up to 140 mg/m2; a subsequent cohort of 15 patients were treated twice daily (b.i.d.) at 100-140 mg/m2/day (50, 60, and 70 mg/m2 b.i.d.) to evaluate a b.i.d. dosing regimen. Headache was the most frequent adverse event and was dose limiting in 3 of 41 patients. Skin toxicity was the next most common toxicity and was seen in 11 of 41 patients; it was typically mild and limited to skin dryness and erythema. Other toxicities included conjunctivitis, flushing, diarrhea, transaminitis, hypercalcemia, and asymptomatic hypertryglyceridemia. Toxicities were typically dose related, occurred primarily above 83 mg/m2/day, and were not ameliorated by b.i.d. dosing. No tumor responses were observed. The mean day 1 area under the plasma concentration-time curve and peak plasma concentration values were dose-proportional over all dose levels, whereas day 15 area under the plasma concentration-time curve and peak plasma concentration values were nonlinear above 83 mg/m2/day, suggesting that 9-cis-RA induced its own metabolism at doses equal to and above 140 mg/m2/day. 9-cis-RA is a retinoid receptor pan agonist with a more favorable pharmacokinetic and toxicity profile than that observed with previously studied retinoids and merits further investigation.     

Respiratory arrest following intrathecal injection of sufentanil and bupivacaine in a parturient

PURPOSE: To present a case of respiratory arrest following the use of intrathecal sufentanil and bupivacaine for combined spinal-epidural anaesthesia in a healthy labouring parturient. CLINICAL FEATURES: A 20-yr-old term parturient received 10 micrograms sufentanil and 2.5 mg bupivacaine intrathecally as part of a combined spinal-epidural technique for labour analgesia. She had received no previous analgesics. Twenty-three minutes after the intrathecal injection she became unresponsive and suffered a respiratory arrest. Resuscitation included manual bag/mask ventilation with oxygen and intravenous naloxone. CONCLUSION: Respiratory arrest is a rare but potentially life-threatening complication associated with the use of intrathecal opioids for labour analgesia. Vigilance in post-procedure patient monitoring is imperative.     

The effect of soy isoflavones on the development of intestinal neoplasia in ApcMin mouse

Large polymeric 3-alkylpyridinium salts have been isolated from the marine sponge Reniera sarai. They are composed of N-butyl(3-butylpyridinium) repeating subunits, polymerized head-to-tail, and exist as a mixture of two main polymers with molecular weights without counterion of about 5520 and 18900. The monomer analogue of the inhibitor, N-butyl-3-butylpyridinium iodide has been synthesized. This molecule shows mixed reversible inhibition of acetylcholinesterase. The polymers also act as acetylcholinesterase inhibitors and show an unusual inhibition pattern. We tentatively describe it as quick initial reversible binding, followed by slow binding or irreversible inhibition of the enzyme. This kinetics suggests that there are several affinity binding sites on the acetylcholinesterase molecule where the polymer can bind. The first binding favors binding to other sites which leads to an apparently irreversibly linked enzyme-inhibitor complex.     

In vitro blood compatibility of surface-modified polyurethanes

Polyurethanes have proven durable materials for the manufacture of flexible trileaflet heart valves, during in vitro tests. The response of two polyurethanes of differing primary structure to parameters of blood compatibility has now been investigated, using an in vitro test cell. Platelet (beta-thromboglobulin) release, complement (C3a) activation, the activation of free plasma and surface-bound factor XII were studied using fresh, human blood (no anticoagulant) or citrated plasma in control and surface-modified polyurethane. Surface modifications were designed to affect material thrombogenicity and included covalent attachment of heparin, taurine, a platelet membrane glycoprotein fragment, polyethylene oxide (PEO), 3-aminopropyltriethoxysilane, and glucose or glucosamine. Unmodified control polyurethanes caused platelet release and complement activation. High molecular weight (2000 D) polyethylene oxide reduced platelet release slightly but only glucose attachment to the surface produced a significant reduction in platelet activation. All modifications reduced C3 activation compared with controls, but the greatest reduction was achieved with polyethylene oxide attachment or glycosylation. Most surface modifications were more activating of factor XII, both in plasma and on the material surfaces, than the control polyurethanes. Heparin and high molecular weight PEO produced the greatest activation of factor XII in the free plasma form, but low molecular weight PEO and glucosamine produced the greatest activation of surface-bound factor XIIa. The least activating surfaces, affecting both free plasma and surface-bound factor XIIa, were those treated with platelet membrane glycoprotein fragment and glucose. PEO surfaces performed relatively well, compared with controls and most surface modifications. The best overall surface, however, was the glucose-modified surface which was least activating considering all parameters of blood compatibility.     

Partial depletion and multiple deletions of muscle mtDNA in familial MNGIE syndrome

OBJECTIVE: To describe the unique combination of partial depletion and multiple deletions of mitochondrial DNA (mtDNA) on muscle DNA analysis of three siblings with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). BACKGROUND: MNGIE is a relatively homogeneous autosomal recessive disorder characterized by gastrointestinal dysmobility, ophthalmoparesis, peripheral neuropathy, mitochondrial myopathy, and altered white matter signal at brain imaging. Muscle multiple mtDNA deletions have been found in about half of the described cases. METHODS: We studied three affected siblings (two were monozygotic twins) born to nonconsanguineous parents. Muscle mtDNA was investigated by quantitative Southern and Slot blot techniques and by PCR analysis. Morphologic confirmation in the muscle tissue was achieved by using in situ hybridization with a mtDNA probe complementary to an undeleted region and by DNA immunohistochemistry. RESULTS: All three patients showed ragged red (RRF) and cytochrome c oxidase-negative fibers, as well as partial deficiency of complexes I and IV. Southern and Slot blot analyses showed mtDNA depletion in all patients. Multiple mtDNA deletions were also detected by PCR analysis. In situ hybridization demonstrated an overall signal weaker than controls, with a relatively higher signal in RRF. Antibodies against DNA showed a decreased cytoplasmic network. CONCLUSIONS: The muscle histopathology and respiratory chain enzyme defects may be accounted for by the decreased mtDNA amount and by the presence of mtDNA deleted molecules; however, relative levels of mtDNA seem to correlate with life span in these patients. The combination of partial depletion and multiple deletions of mtDNA might indicate the derangement of a common genetic mechanism controlling mtDNA copy number and integrity.     

Disease and sleep satisfaction at age 70

A new arylnaphthalene lignan, 9-(1,3-benzodioxol-5-yl)-4,5,6, 7-tetramethoxynaphtho[2,3-C]furan-1(3H)-one (5-methoxyjusticidin A, 1), was isolated from a Et2O extract of the wood of Protium unifoliolatum. The structure of 1 was determined by both spectroscopic and X-ray crystallographic methods.