Minority Block Research Articles

Selective distribution of interacting magnetic nanoparticles into block copolymer domains based on the facile inversion of micelles

We demonstrate a simple methodology to incorporate interacting magnetic nanoparticles (mNPs) into cylinder forming block copolymer templates. Poly(styrene- block-isoprene) (PS- b-PI) with PI cylinders and poly(styrene- block-4vinylpyridine) (PS- b-P4VP) with PS cylinders were used as the block copolymer templates and γ-Fe 2O 3 NPs coated with oleic acids were pre-synthesized for the interacting mNPs. Regardless of the template block copolymers, the selective location of mNPs and the size of mNP aggregates are clearly altered by changing casting solvents. When good solvents for both blocks were used as casting solvents, mNPs are readily aggregated during the solvent evaporation. In contrast, under selective casting solvents for the minor blocks, the mNPs were selectively trapped into the cylinder domains through the facile inversion of micelles during solvent evaporation. The interplay between mNPs and block copolymers was also tested with different molecular weights of block copolymers.

Self‐Supporting, Double Stimuli‐Responsive Porous Membranes From Polystyrene‐block‐poly(N,N‐dimethylaminoethyl methacrylate) Diblock Copolymers

AbstractAsymmetric membranes are prepared via the non‐solvent‐induced phase separation (NIPS) process from a polystyrene‐block‐poly(N,N‐dimethylaminoethyl methacrylate) (PS‐b‐PDMAEMA) block copolymer. The polymer is prepared via sequential living anionic polymerization. Membrane surface and volume structures are characterized by scanning electron microscopy. Due to their asymmetric character, resulting in a thin separation layer with pores below 100 nm on top and a macroporous volume structure, the membranes are self‐supporting. Furthermore, they exhibit a defect‐free surface over several 100 µm2. Polystyrene serves as the membrane matrix, whereas the pH‐ and temperature‐sensitive minority block, PDMAEMA, renders the material double stimuli‐responsive. Therefore, in terms of water flux, the membranes are able to react on two independently applicable stimuli, pH and temperature. Compared to the conditions where the lowest water flux is obtained, low temperature and pH, activation of both triggers results in a seven‐fold permeability increase. The pore size distribution and the separation properties of the obtained membranes were tested through the pH‐dependent filtration of silica particles with sizes of 12–100 nm.

Tetragonally Packed Cylinder Structure of Comb−Coil Block Copolymer Bearing Heteroarm Star Architecture

Block copolymers form a special class of soft materials capable of self-assembling into a variety of long-range ordered nanostructures. In the melt state the microphase separation between the incompatible blocks generates the micelle comprising the microdomain composing of the minority block and the corona consisting of the majority block. The classical microdomains are lamellae, cylinder, and sphere. The interaction between the micelles further results in long-range ordered spatial arrangement of the microdomains.

Effect of Composition of Substrate-Modifying Random Copolymers on the Orientation of Symmetric and Asymmetric Diblock Copolymer Domains

The ability of random copolymer brushes and cross-linked mats to induce the vertical orientation of domains in overlying films of lamellae- and cylinder-forming block copolymers was investigated as a function of the composition. The substrate-modifying layers consisted of styrene and methyl methacrylate random copolymers and contained either a terminal hydroxyl group or a third polar comonomer of 2-hydroxyethyl methacrylate (HEMA) for grafting brushes to silicon oxide surfaces or glycidyl methacrylate (GMA) for cross-linking the random copolymer into a mat. Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) lamellae- and cylinder-forming block copolymers (both PS and PMMA minority block copolymers) were deposited and annealed on the modified surfaces. In all cases the vertical orientation of domains was observed for a range of random copolymer composition, but the ranges of composition were different for each combination of surface layer and block copolymer. The cylindrical domains of PS exhibited vertical structures for a very narrow range of compositions compared to cylindrical domains of PMMA or lamellae. As expected, the incorporation of polar HEMA or GMA monomers in the surface layers shifted the composition range for the perpendicular orientation of domains to higher fractions of styrene. The results are discussed in terms of the equilibration of the films in the presence of the chemically modified surfaces.

Corporate Block Acquisitions around the World

Between 1990 and 2005, 14 percent of the world's public firms were targets in minority block acquisitions, of which one third were cross-border. These target firms are mostly financially constrained, experience significant increases in their stock prices at the announcement and increase their investment expenditures subsequent to the acquisition. In the immediate two years following the acquisition, 27 percent of target firms issue new equity and 10 percent issue new debt. The size of these new issues is between 23 and 27 percent of the target firms' market capitalization. These findings are consistent with the theory that equity stakes by other corporations certify the investment opportunities of target firms and allow them to raise additional capital. There is little evidence in support of competing theories that corporate blockowners lower contracting costs in the product market, effectively monitor insiders or capitalize on their overvalued stocks.

Morphology Development in Asymmetric Poly(styrene-b-tert-butylacrylate) Thin Films by Solvent Annealing

Morphology dependence of asymmetric poly(styrene-b-tert-butylacrylate) [P(S-b-tBA)] thin film on casting solvent, annealing solvent and annealing time was investigated. Two casting solvents, toluene and propylene glycol monomethyl ester acetate (PGMEA), and two annealing solvents, p-xylene and tert-butylacrylate (tBA), were studied. The casting solvent dominated the initial morphology. P(S-b-tBA) film cast from toluene resulted in inverted phase (PtBA cylinders in PS matrix) and the one cast from PGMEA led to normal phase (PS cylinders in PtBA matrix) morphology. The annealing solvents preference to either the majority or the minority block in combination with the annealing time controlled the orientation of the cylinders. When the annealing solvent preferentially interacted with the majority block in the as-cast film, a metastable highly ordered perpendicular cylinder morphology was trapped. The best conditions to obtain perpendicular PS cylinders were casting P(S-b-tBA) film from PGMEA and annealing in tBA vapor for 20 and 25 min on silicon and NaCl substrates

PEO based Block Copolymer as Solid State Lithium Battery Electrolyte

We report the use of a conductive electrolyte matrix containing a secondary source of lithium templated by the microphase separation of a block copolymer. The desired polymer matrix is synthesized by hydrolyzing a block copolymer of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA), to generate a lithium salt of acrylic acid in the minority block (PMAALi), resulting in a block copolymer with a random copolymer as its second block, PEO-b-(PMMA-ran-PMAALi). The electrolyte composition was optimized at (ethylene oxide : lithium bis(oxalato)borate = 3:1) and exhibited nearly an order of magnitude higher conductivity than PEO of similar molecular weight and salt composition.

São Luís Craton and Gurupi Belt (Brazil): possible links with the West African Craton and surrounding Pan-African belts

Abstract The São Luís Craton and the Palaeoproterozoic basement rocks of the Neoproterozoic Gurupi Belt in northern Brazil are part of an orogen having an early accretionary phase at 2240–2150 Ma and a late collisional phase at 2080±20 Ma. Geological, geochronological and isotopic evidence, along with palaeogeographic reconstructions, strongly suggest that these Brazilian terrains were contiguous with the West African Craton in Palaeoproterozoic times, and that this landmass apparently survived subsequent continental break-up until its incorporation in Rodinia. The Gurupi Belt is an orogen developed in the southern margin of the West African–São Luís Craton at c . 750–550 Ma, after the break up of Rodinia. Factors such as present-day and possible past geographical positions, the timing of a few well-characterized events, the structural polarity and internal structure of the belt, in addition to other indirect evidence, all favour correlation between the Gurupi Belt and other Brasiliano/Pan-African belts, especially the Médio Coreaú domain of the Borborema Province and the Trans-Saharan Belt of Africa, despite the lack of proven physical links between them. These Neoproterozoic belts are part of the branched system of orogens associated with amalgamation of the Amazonian, West Africa–São Luís, São Francisco and other cratons and minor continental blocks into the West Gondwana supercontinent.

CD36 Is Differentially Expressed on B Cell Subsets during Development and in Responses to Antigen

Of a number of mAbs made by immunization with sort-purified marginal zone (MZ) B cells, one was shown to recognize the mouse scavenger receptor CD36. Although CD36 is expressed by most resting MZ B cells and not by follicular and B1 B cells, it is rapidly induced on follicular B cells in vitro following TLR and CD40 stimulation. In response to T-independent and T-dependent Ag challenge, we found that CD36 was expressed on IgM+ plasma cells, but down-regulated on isotype-switched plasma cells in vivo. Although development, localization, and phenotype of MZ B cells in CD36-/- mice appeared normal, there was a minor block in the transitional stages of mature B cell development. In both primary and secondary Ab responses to heat-killed Streptococcus pneumoniae (R36A strain), both phosphoryl choline (PC)-specific IgM and IgG levels in CD36-/- mice were slightly reduced compared with wild-type mice. In addition, mice deficient in both TLR2 and CD36 produced significantly reduced levels of anti-PC IgG titers than those of single gene-deficient mice, suggesting that they may cooperate in an anti-PC Ab response. Collectively, these results show that CD36 does not affect the development of B cells, but modulates both primary and secondary anti-PC Ab responses during S. pneumoniae infection similarly to TLR2.

Ion probe zircon dating of metasediments from the Areachap and Kakamas Terranes, Namaqua-Natal Province and the stratigraphic integrity of the Areachap Group

Ion probe U-Pb dating of different age domains within detrital zircons, distinguished using cathodoluminescent images, has been applied to three metasedimentary gneiss samples from the Jannelsepan, Copperton and Kenhardt Formations in the Areachap and Kakamas Terranes of the Namaqua-Natal Province. The Areachap Group samples yielded largely coherent ages which are considered to reflect the age of extrusion of the surrounding volcanic rocks. These are 1275 ± 7 Ma for the Jannelsepan Formation at Boksputs (with a component at ~1301 Ma) and 1282 ± 45 Ma for the Copperton Formation at Prieska Copper Mines. Direct dates of volcanic rocks in these formations in the literature are 1241 ± 12 Ma for the Jannelsepan Formation at Upington and 1285 ± 14 Ma for the Copperton Formation. The Kenhardt Formation sample contained three age domains. Concordant zircon cores dated at 1568 ± 23, 1351 ± 24 and 1296 ± 14 Ma reflect the presence of older crustal material in the Kakamas Terrane, whereas another six cores are coeval with the main, oscillatory zoned phase, dated at 1194 ± 7 Ma. This is the age of the magmatic rocks from which this metasedimentary sample was derived. The identity of the Areachap Group as defined in the 1980s has been questioned on the grounds that the Boven Rugseer Shear Zone is a terrane boundary that cuts across the Areachap Group. This work shows that the Jannelsepan and Copperton Formations, which crop out to the north and south of this shear zone, both formed in the interval ~1.30 to ~1.24 Ga. Published geochemical data show that these formations have a common origin as arc-related volcanosedimentary sequences containing volcanic massive sulphide ore deposits. Furthermore the Pb and sulphur isotopic data point to very similar sources of mineralization in the Areachap Mine (Jannelsepan Fn) and Prieska Copper Mines (Copperton Fn). We conclude that the integrity of the Areachap Group as originally defined rests on very strong evidence. The new data are compatible with a tentative plate tectonic model for the region. The ~1.57 Ga Kakamas fragment and the juvenile ~1.3 Ga Areachap Arc are envisaged as minor crustal blocks in a major ocean basin bounded by the major Bushmanland continental block and the Kaaien-Kheis-Kaapvaal block. The Wilgenhoutsdrift Group formed at the same time as the Areachap Group in a back-arc or rift setting on the margin of the Kalahari Craton, from which it derived Palaeoproterozoic and Archean sedimentary material. Assembly of all the terranes by collision following closure of the major ocean basin gave rise to a collision-related cycle of D1-D2 deformation, metamorphic events and migmatisation at different localities between 1194 ± 23 and 1158 ± 7 Ma. A much later thermal event originating in the mantle affected the whole region at ~1.1 Ga, leading to extensive magmatism, D3 deformation and local migmatisation.

Inhibition of Toxoplasma gondii growth by pyrrolidine dithiocarbamate is cell cycle specific and leads to population synchronization

Successful completion of the Toxoplasma cell cycle requires the coordination of a series of complex and ordered processes that results in the formation of two daughters by internal budding. Although we now understand the order and timing of intracellular events associated with the parasite cell cycle, the molecular details of the checkpoints that regulate each step in Toxoplasma gondii division is still uncertain. In other eukaryotic cells, the use of cytostatic inhibitors that are able to arrest replication at natural checkpoints have been exploited to induce synchronization of population growth. Herein, we describe a novel method to synchronize T. gondii tachyzoites based on the reversible growth inhibition by the drug and pyrrolidine dithiocarbamate. This method is an improvement over other strategies developed for this parasites as no prior genetic manipulation of the parasite was required. RH tachyzoites blocked by pyrrolidine dithiocarbamate exhibited a near uniform haploid DNA content and single centrosome indicating that this compound arrests parasites in the G1 phase of the tachyzoite cell cycle with a minor block in late cytokinesis. Thus, these studies support the existence of a natural checkpoint that regulates passage through the G1 period of the cell cycle. Populations released from pyrrolidine dithiocarbamate inhibition completed progression through G1 and entered S phase ∼2 h post-drug release. The transit of drug-synchronized populations through S phase and mitosis followed a similar timeframe to previous studies of the tachyzoite cell cycle. Tachyzoites treated with pyrrolidine dithiocarbamate were fully viable and completed two identical division cycles post-drug release demonstrating that this is a robust method for synchronizing population growth in Toxoplasma.

Micro-phase separation of diblock copolymer in a nanosphere: Dissipative particle dynamics approach

Micro-phase separation and morphologies of diblock copolymer in a nanosphere with different size and interfacial energy were studied by dissipative particle dynamics approach. The surface of a nanosphere is modeled by a layer of frozen soft particles. For symmetric diblock copolymer A 5B 5, if the surface is neutral, i.e., with the same interactions toward different blocks, the morphology consists of bended distorted lamellae connected by channels. They might be mushroom-like, helical or bi-continuous depending on the sphere size. When the surface is non-neutral, i.e., with the different interactions toward different blocks, the meso-structure is onion like. The outmost layer is the block with weaker repulsion toward the surface. The number of the alternative inner layers is determined by the size. For asymmetric diblock, the morphology is strong associated with the composition. For A 3B 7, owing to the strong restriction of the nanosphere, the hexagonal phase originally in the bulk does not occur. When the surface is neutral, the minority block forms bended sticks touched the surface. With the increase of the sphere size, more and more cylindrical or star like joints link these sticks. When the surface is non-neutral and less repulsive toward the minority block, more bended sticks near the nanosphere surface than those in the neutral nanosphere. Increasing the sphere size causes spherical and cylindrical domain formed in the center of the sphere. For A 2B 8, the minority A-block forms spheres or peanut like domains consisting concentric spheres; the number of them is related to the sphere size. However, for A 1B 9, no micro-phase separation was found. The polymer surfactant in aqueous solution was also studied. The results indicate that the polymer in a nanosphere can be used to mimic the polymer surfactant in some cases.

The ω-atracotoxins: Selective blockers of insect M-LVA and HVA calcium channels

The ω-atracotoxins (ω-ACTX) are a family of arthropod-selective peptide neurotoxins from Australian funnel-web spider venoms (Hexathelidae: Atracinae) that are candidates for development as biopesticides. We isolated a 37-residue insect-selective neurotoxin, ω-ACTX-Ar1a, from the venom of the Sydney funnel-web spider Atrax robustus, with high homology to several previously characterized members of the ω-ACTX-1 family. The peptide induced potent excitatory symptoms, followed by flaccid paralysis leading to death, in acute toxicity tests in house crickets . Using isolated smooth and skeletal nerve-muscle preparations, the toxin was shown to lack overt vertebrate toxicity at concentrations up to 1 μM. To further characterize the target of the ω-ACTXs, voltage-clamp analysis using the whole-cell patch-clamp technique was undertaken using cockroach dorsal unpaired median neurons. It is shown here for the first time that ω-ACTX-Ar1a, and its homolog ω-ACTX-Hv1a from Hadronyche versuta, reversibly block both mid–low- (M-LVA) and high-voltage-activated (HVA) insect calcium channel (Ca v) currents. This block occurred in the absence of alterations in the voltage-dependence of Ca v channel activation, and was voltage-independent, suggesting that ω-ACTX-1 family toxins are pore blockers rather than gating modifiers. At a concentration of 1 μM ω-ACTX-Ar1a failed to significantly affect global K v channel currents. However, 1 μM ω-ACTX-Ar1a caused a modest 18% block of insect Na v channel currents, similar to the minor block of Na v channels reported for other insect Ca v channel blockers such as ω-agatoxin IVA. These findings validate both M-LVA and HVA Ca v channels as potential targets for insecticides.

Pectoralis minor obstruction of the axillary vein: Report of six patients

Although the usual site of nonthrombotic venous obstruction of the upper extremity is the subclavian vein, other sites may be the cause of such obstruction. This study describes the diagnosis and treatment of six patients with partial axillary vein obstruction by the pectoralis minor muscle, a condition that can mimic subclavian vein obstruction. A chart review of patients undergoing pectoralis minor tenotomies (PMT) between 2004 and 2006 revealed six patients (3 men and 3 women), aged 17 to 39, who underwent seven PMT procedures for symptoms of arm swelling, cyanosis, and pain or tightness. Diagnosis was suggested by history and physical examination and was confirmed by dynamic venography. Patients with paresthesia suggesting associated neurogenic pectoralis minor compression were given a pectoralis minor muscle block. As an outpatient, PMT was initially performed with an infraclavicular approach but later through the transaxillary route. Follow-up was by phone interview in five patients and a physical examination in one. Venography demonstrated axillary vein compression under the pectoralis minor, which was more significant than the minor degree of subclavian vein compression seen on the same venogram. Follow-up was 1.5 years to 10 years in three patients and 3 months in the other three. All six patients experienced good-to-excellent relief of all symptoms. There were no surgical complications. Axillary venous obstruction by the pectoralis minor must be distinguished from subclavian vein obstruction, which presents with similar symptoms. PMT is a simple, risk-free, outpatient procedure that has produced uniformly good results.

Continuous Regional Anesthesia After Foot Surgery in Children

In Response: Dr. Setzer is correct regarding the fentanyl dose noted in our article (1). There was a typographical error and the correct fentanyl dose was 0.62–0.98 μg/kg. In response to the second comment, and similar to the results in our earlier studies (2,3), concerning the effects of continuous peripheral nerve blocks, we did not note any major motor block in this study. The small volume and small concentration of ropivacaine produced a differential blockade in children (4). Moreover, after podiatric surgery, a plaster cast is applied and the adverse effect of minor motor block, under a cast, is probably less uncomfortable than nausea, vomiting, or urinary retention. The assessment of motor block is especially important to limit the risk of a compartimental syndrome or pressure sores (5). Christophe Dadure, MD Xavier Capdevila, MD, PhD Department of Anesthesia A Lapeyronie University Hospital Montpellier, France [email protected]

Self-Assembled Morphologies of a Diblock Copolymer Melt Confined in a Cylindrical Nanopore

We systematically investigate the microdomain morphologies that self-assemble in a diblock copolymer melt confined to a narrow cylindrical nanopore using real-space self-consistent mean-field theory. We observe, for a bulk cylinder-forming copolymer, that a variety of novel microdomain structures emerge under confinement. As the pore diameter increases, the following sequence of stable structures occurs: single cylinder, stacked disks, single helix, double helix, toroid−sphere, and helix−cylinder. We accurately locate the pore diameters where first-order phase transitions between these morphologies occur. We vary the interaction of the diblock copolymer with the pore wall from being preferential for the minority block to neutral to being preferential for the majority block and find that the sequence of structures is unchanged, for these interactions. The pitch angle of the helices and the pore diameter can be related using a simple geometrical argument. Over the range of pore diameters we examine, phases...

Control of Self-Assembly by Charge-Transfer Complexation between C60Fullerene and Electron Donating Units of Block Copolymers

Self-assembly allows new opportunities to control the morphology and properties of fullerene-based materials. By using the electron-accepting underivatized C60 and electron-donating pyridine groups of a polystyrene-block-poly(4-vinylpyridine), PS-block-P4VP, we here show the first example that charge-transfer complexation between fullerenes and block copolymers can essentially modify the self-assembled structures. The morphology of C60/PS-block-P4VP mixture is studied in both bulk and thin films by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) upon casting from freshly prepared or differently aged xylene solutions. Selecting PS-block-P4VP that leads to hexagonal self-assembly with P4VP cylindrical cores, closely similar cylindrical structure is observed upon adding a small amount of C60, when freshly prepared xylene solutions are used to cast solid bulk or thin film samples. In this case the C60 molecules swell the PS matrix. By contrast, spherical morphology is observed if aged xylene solutions have been used where C60 has slowly penetrated into the P4VP micellar cores due to charge-transfer complexation, as evidenced by UV−vis and FTIR spectroscopy. This morphological change is unexpected, as according to simple block copolymer theory selective incorporation of a small molecular species or nanoparticles within the minority block of hexagonally self-assembled cylindrical diblock copolymer system should render the morphology toward lamellar structures. This suggests that charge-transfer complexation can be relevant in considering the self-assembled structures of block copolymers and fullerenes.

Phase behavior and microstructural length scales of a diblock copolymer in the presence of a selective solvent

We employ self-consistent mean-field (SCMF) theory in studying the phase behavior as well as the microstructural domain sizes for a diblock copolymer in the presence of a selective solvent. First we examine the effects of solvent addition on the formation of fcc and bcc packed spheres. As has been found in experiments, the so-called “normal” spheres, i.e., formed by the minority blocks, tend to pack into the bcc array, while the “inverted” spheres formed by the majority blocks favor the fcc packing. Upon increasing the solvent selectivity and/or solvent amount, the formed inverted spheres tend to pack from bcc to fcc. This thermotropic transition of bcc → fcc upon increasing the solvent selectivity is induced by the fact that the intermicellar interactions vary from long-range to short-range via a combination of the solvent exclusion from the cores and an increase in the aggregation number. In analyzing the effects of solvent addition on the microstructural sizes, the SCMF results have successfully captured the crossover behavior of characteristic domain spacing from decreasing with added solvent to increasing by increasing the solvent selectivity. Further, the variation of the characteristic domain spacing when the systems transform to a more curved structure changes from a discontinuous decreasing behavior to even a discontinuous increasing behavior upon increasing the solvent selectivity and/or the formation of inverted structures.

Self-consistent field study of the alignment by an electric field of a cylindrical phase of block copolymer

Self-consistent field theory is applied to a film of cylindrical-forming block copolymer subject to a surface field which tends to align the cylinders parallel to electrical plates, and to an external electric field tending to align them perpendicular to the plates. The Maxwell equations and self-consistent field equations are solved exactly, numerically, in real space. By comparing the free energies of different configurations, we show that for weak surface fields, the phase of cylinders parallel to the plates makes a direct transition to a phase in which the cylinders are aligned with the field throughout the sample. For stronger surface fields, there is an intermediate phase in which cylinders in the interior of the film, aligned with the field, terminate near the plates. For surface fields which favor the minority block, there is a boundary layer of hexagonal symmetry at the plates in which the monomers favored by the surface field occupy a larger area than they would if the cylinders extended to the surface.

AN EXAMINATION OF MECHANISMS UNDERLYING THE SURVIVAL BENEFIT CONFERRED BY INTESTINESPECIFIC OVEREXPRESSION OF INTERLEUKIN-10

Background: We have shown that transgenic (TG) mice overexpressing IL-10 in the intestine have a significant survival advantage over their wildtype (WT) counterparts when challenged with cecal ligation and puncture (CLP). The mechanism underlying this survival advantage is unknown. Objective: To determine mechanisms responsible for the survival advantage conferred by intestine-specific overexpression of IL- 10. Methods: Given the documented role of IL-10 on systemic inflammation, the gut, and the lungs, each was examined in detail in septic TG and WT mice. TG (n=13) and WT (n=14) mice were subjected to CLP with a 1 by 27 injury. The animals were sacrificed 24 hours later and intestines, lungs, serum, and bronchoalveolar lavage (BAL) fluid were collected. The serum and BAL were spun down and assayed for cytokines IL-12, TNFa, IFN, MCP-1, IL-10, and IL-6 using cytometric bead analysis. Intestines and lungs were sectioned and stained by H&E. Intestines were assessed for epithelial apoptosis in 100 intact crypt-villus units while the lungs were assessed qualitatively. A piece of the intestine was also used to evaluate permeability utilizing the everted gut sac model. Results: IL-12 levels were lower (p <.05) in the serum of transgenic mice (5.1 +/− 0.5 vs. 6.7 +/− 0.5) with no significant differences in the other serum or BAL cytokines measured. There was no statistically significant disparity in intestinal apoptosis, and lung histology was unremarkable. Evaluation of clearance in the intestine revealed no significant difference in permeability. Conclusions: Intestinal production of IL-10, an anti-inflammatory cytokine, induces a minor downstream block of systemic IL-12 expression in septic animals but has no effect on other serum or BAL cytokines, gut permeability and apoptosis, and lung histology. The main mechanisms underlying the survival advantage conferred by intestinal overexpression of IL-10 remain to be determined.