Weight Of Segment Research Articles

On the Viscoelastic Segment Size of Cellulose

Dynamic birefringence and viscoelasticity of cellulose acetate propionate were measured at various temperatures covering a wide frequency region from the rubbery plateau to the glassy zone in order to determine the viscoelastic segment size of cellulose. The complex Young's modulus was separated into two components, R and G components. From the limiting modulus at high frequencies of the R component, molecular weight of viscoelastic segment was determined as 3100. This value is the largest one among amorphous polymers previously determined. Larger dynamic segment size reflects the rigid chain structure of β linked D-glucose units (about 10 glucose units per segment). Number of segments per entanglement strand was also estimated to be 4. Reflecting the small segment number per entanglement strand, most of reorientation of segment (relaxation of stress) was found to be delayed until the terminal flow zone.

Light and Scanning Electron Microscopy of the Intestine of the Young Red Jungle Fowl (Gallus gallus)

Thirty males of Red Jungle Fowl (RJF) were divided into 3 equal groups, euthanized at day 1, 10 and 20 days after hatching. The morphometric analyses were performed at three different magnification levels. Different segments (duodenum, jejunum and ileum) and cecum were weighted and length of each small intestinal segments and cecum were determined at a macroscopic level. The mucosa of the intestinal segments was compared and contrasted using both, light and scanning electron microscopy. The villi height, villi surface area, crypt depth and muscularis externa were measured. The body weight was doubled at 10th day and again doubled at 20th day. The weight and length of intestinal segments were significantly higher throughout the experiment except the constant rate of the duodenal and jejunal lengths after 10th days. Relative to body weight, the organs weight and length were declined after 10th days. The duodenal villi height and surface area were greater than the jejunum followed by the ileum. The muscularis externa and crypt depth increased significantly at 10th day. However, the latter showed retardation thereafter. Day one intestinal villi appeared finger-like shape with zigzag arrangement, tongue-like and leaf-like shaped in 10 and 20th days, respectively. The villi distribution and patterns in the middle region of cecum were characteristic. The epithelial cells of the duodenal villi showed more activities and development than those on the jejunum and the ileum throughout the age. The body growth in RJF progresses very slowly while the relative intestinal segment weight and length failed to follow the body weight after 10th days. The duodenal mucosa shows better developmental features than the jejunum and the ileum.

Comparison of anatomy-based, fluence-based and aperture-based treatment planning approaches for VMAT

Volumetric modulated arc therapy (VMAT) has the potential to reduce treatment times while producing comparable or improved dose distributions relative to fixed-field intensity-modulated radiation therapy. In order to take full advantage of the VMAT delivery technique, one must select a robust inverse planning tool. The purpose of this study was to evaluate the effectiveness and efficiency of VMAT planning techniques of three categories: anatomy-based, fluence-based and aperture-based inverse planning. We have compared these techniques in terms of the plan quality, planning efficiency and delivery efficiency. Fourteen patients were selected for this study including six head-and-neck (HN) cases, and two cases each of prostate, pancreas, lung and partial brain. For each case, three VMAT plans were created. The first VMAT plan was generated based on the anatomical geometry. In the Elekta ERGO++ treatment planning system (TPS), segments were generated based on the beam's eye view (BEV) of the target and the organs at risk. The segment shapes were then exported to Pinnacle3 TPS followed by segment weight optimization and final dose calculation. The second VMAT plan was generated by converting optimized fluence maps (calculated by the Pinnacle3 TPS) into deliverable arcs using an in-house arc sequencer. The third VMAT plan was generated using the Pinnacle3 SmartArc IMRT module which is an aperture-based optimization method. All VMAT plans were delivered using an Elekta Synergy linear accelerator and the plan comparisons were made in terms of plan quality and delivery efficiency. The results show that for cases of little or modest complexity such as prostate, pancreas, lung and brain, the anatomy-based approach provides similar target coverage and critical structure sparing, but less conformal dose distributions as compared to the other two approaches. For more complex HN cases, the anatomy-based approach is not able to provide clinically acceptable VMAT plans while highly conformal dose distributions were obtained using both aperture-based and fluence-based inverse planning techniques. The aperture-based approach provides improved dose conformity than the fluence-based technique in complex cases.

Growing up in the temperate zone: Age, growth, calcification and carbonate mineralogy of Melicerita chathamensis (Bryozoa) in southern New Zealand

The cheilostome bryozoan Melicerita chathamensis from the continental shelf around southern New Zealand is unusual in having macroscopic annual growth checks. It thus presents an opportunity to examine annual variations in age, growth, calcification and carbonate mineralogy in a temperate bryozoan. Forty-one colonies dredged south of Snares Islands, New Zealand (47° 49.537′S, 166° 45.910′E, 166 m water depth, 2 February 2008) ranged from 2 to 9 years old and were up to 40 mm long. Segment length varied from 0.94 to 13.67 mm, with a mean growth rate of 5.27 mm yr − 1 , whereas segment weight varied from 0.1 to 37 mg, with an average calcification rate of 9.2 mg yr − 1 . Low-Mg calcite ranged from 0.8 to 3.6 wt.% MgCO 3, with a mean of 2.1 wt.% MgCO 3, whereas high-Mg calcite ranged from 6.6 wt.% MgCO 3 to 9.7 wt.% MgCO 3 with a mean of 8.1 wt.% MgCO 3. The well-studied polar Melicerita obliqua, in contrast, grows more slowly over a much longer period and calcifies more rapidly, suggesting that polar bryozoans may be more effective at sequestering carbon than their temperate counterparts. The proportion of each mineral in skeletal segments generally varied with age, from almost entirely high-Mg calcite in the oldest segments to entirely low-Mg calcite at the growing tips, with a mean of 60.7% high-Mg calcite. This unusual dual-calcite mineralogy appears to be analogous to some other cheilostomes which also produce a primary skeleton of low-Mg calcite but their secondary mineral is aragonite. Such bimineralic bryozoans, which are sophisticated mineralisers that exert a great deal of control over their skeletal composition, may be able to mineralise despite decreasing sea-water pH. Bimineral skeletal sediments, however, could be especially vulnerable to dissolution, as both aragonite and high-Mg calcite are more soluble than low-Mg calcite. Weakening of the skeleton by dissolution of secondary thickening could increase the likely effects of temperate abrasion and bioerosion.

Effects of soft monomers on the water resistance and moisture permeability of hydrophilic polyurethane

Six groups of segmented polyurethanes with amorphous soft segment domains based on mixed hydrophobic polyester and hydrophilic polyether soft monomers were prepared from 4, 4′-diphenylmethane diisocyanate (MDI), polybutylene adipate glycol 2000 (PBA2000), polytetramethylene glycol 1000 (PTMG1000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as the chain extender. Furthermore, the representative properties of the hydrophilic polyurethanes, moisture permeability and water resistance, were investigated. The results show that the chemical structure, molecular weight and concentration of soft monomers have remarkable effects on the main application properties of hydrophilic polyurethane. The important factors in diffusion are the content of hydrophilic ether bond and the mobility of hydrophilic chain in the soft phase, which is represented with a good approximation by the average mean molecular weight of soft segment. On the contrary, the functional properties of the hydrophilic polyurethane are almost not affected by its hard segment.

Poly(propylene glycol)‐based ammonium ionenes as segmented ion‐containing block copolymers

AbstractThe synthesis and characterization of series of segmented poly(propylene glycol) (PPG)‐based ammonium ionenes is described. Bromine end‐capped oligomers were successfully synthesized using the reaction of 6‐bromohexanoyl chloride with 1000, 2000, and 4000 g/mol PPGs. 1H NMR spectroscopy, titration studies, and matrix‐assisted laser desorption ionization‐time of flight (MALDI‐TOF) mass spectrometry revealed the difunctionality of the oligomers. First, a series of PPG‐based ammonium ionenes was synthesized from bromine end‐capped PPG oligomers and N,N,N′,N′‐tetramethyl‐1,6‐hexanediamine. For this series, a single glass transition temperature (Tg) of approximately −66 °C was observed through differential scanning calorimetry (DSC); dynamic mechanical analysis (DMA) showed the onset of flow ranged from 20 to 80 °C. In addition, a series of PPG‐based ammonium ionenes containing 1,12‐dibromododecane was synthesized to increase the aliphatic hard segment (HS) content and enhance the mechanical properties of the resulting materials. For these, two Tg's were observed using DMA; DMA also showed the onset of flow of ionenes containing higher HS content (33 wt %) occurred in the range of 100–140 °C. Tensile analysis for these ionenes demonstrated an average tensile strength at break ranging from 0.2 to 2.4 MPa. Small angle X‐ray scattering (SAXS) profiles for these ionenes showed that Bragg distances increase linearly with the molecular weight of PPG soft segment. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4159–4167, 2010

Surface Behavior of PSn(P2VP-b-PtBA)n Heteroarm Stars

We report the surface behavior and morphologies of two series of pH-responsive amphiphilic heteroarm star block copolymers. In this respect, we studied polystyrene/poly(2-vinylpyridine)/poly(tert-butylacrylate), PSn(P2VP-PtBA)n, heteroarm star block terpolymers and their precursors, PSnP2VPn, star copolymers. These star block polymers differ in architecture (copolymer vs terpolymer), block topology, arm length (molecular weight of PtBA segments varies from 8 900 up to 15 250 Da), and number of arms (n = 9, 22, and 28). The π−A isotherms at different subphase pH (pH 5.8 and 2.0) exhibited strong pH dependence, leading to different limiting molecular area and surface micelle stability. Because of the pH-induced ionization of the P2VP block, the surface morphology of star copolymers bearing the free P2VP arms was strongly dependent on the pH of the subphase, whereas the star terpolymers containing the protonated hydrophilic P2VP block as midblocks maintained the same circular morphology at low pH and high pr...

Facile syntheses, morphologies, and optical absorptions of P3HT coil‐rod‐coil triblock copolymers

AbstractHere we report syntheses, photophysical properties, and morphologies of a series of coil‐rod‐coil ABA triblock copolymers containing highly regioregular poly(3‐hexylthiophene) (P3HT) as the central rod block. A new methodology, based on the coupling reaction between living polymeric anions [polystyrene, polyisoprene, and poly(methyl methacrylate)] and aldehyde terminated P3HT, was successfully developed to synthesize the triblock copolymers with low polydispersities. This coupling reaction was effective for building blocks with a variety of molecular weights; therefore, a good variation in compositions of the triblock copolymers could be feasibly achieved. The non‐P3HT coil segments and the solvents were found to exhibit noticeable effects on morphologies of the spin‐coated thin films. Attachment of the coil segments to P3HT did not change the optical absorption of the P3HT segment as the block copolymers were dissolved in solution regardless the chemical structure and the molecular weight of the coil segment. Interestingly, different UV–vis absorption behaviors were observed for the spin‐coated thin films of the block copolymers, which closely related to their morphologies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3311–3322, 2010

Growth Evaluation of Selected Digestive Organs from Day One to Four Months Post-Hatch in Two Breeds of Chicken Known to Differ Greatly in Growth Rate

The digestive organs of Malaysian Village Fowl (MVF) and Broiler Breed (BB) differ in body weight were studied grossly and histologically. Weight of digestive organs and length of small intestine were obtained from fifty male from each breed euthanased from first day after hatch to 4 months. At day 20 body weight of BB was five times greater than those of MVF. The differences between breeds for the weight of vitelline residue, proventriculus, gizzard, liver, pancreas, weight and length of small intestine segments for the absolute and relative to body weight at day one were also obtained. The liver, pancreas and intestinal segments of the two breeds showed increased in relative weight at the 10 days post-hatch and after that the relationship were reversed. At days 20-4 months post-hatch, all organs relative weight of MVF increased except jejunum in 56-120 days and ileum in 56 days. The same patterns observed for intestinal length in both breeds. Day one post-hatch relative lengths of all intestinal segments in MVF were higher than BB. The latter was dominantly showed larger proventricular glands, gizzard glands and gizzard lining membrane. In BB, the villi heights of intestinal mucosa were higher than that of MVF, except in ileum at days 20 and 56 post-hatch. The villus surface areas were constantly greater in BB, the crypt depths were greater in BB, except in 56 and 120 days. There were no different in thickness of muscularis externa in each intestinal segment at the day one and after the 20 days old.

SU‐GG‐T‐162: Using Tumor Motion Trajectory as a Constraint for 4D‐IMRT Treatment Planning

Purpose: To develop a 4D‐IMRT treatment planning technique by adding a tumor motion trajectory (TMTJ) as a constraint in a commercially available Treatment Planning System (TPS). The goal is to create an IMRT plan with a set of MLC segments catering for the motion of the patient anatomy extracted from 4D‐CT images. Method and Materials: 4D‐CT images were obtained from three lung cancer patients. The 4D protocol divided the breathing cycle into ten phases followed by a Maximum Intensity Projection (MIP) volume reconstruction. ITVs were contoured based on the MIP volumes. GTVs were contoured on all ten CT phases to generate a TMTJ, defined as the position of the centroid of the GTV on all phases. A tube shaped contour (TBC) with about 1 cm diameter along the TMTJ and inside the GTV was generated. TBC was added to the objective function as a constraint with minimum dose‐volume histogram (DVH) set to prescribed dose. IMRT plans were generated by using Pinnacle DMPO with and without the TMTJ constraint. Results: The IMRT plans generated with TMTJ constraints optimized the MLC segment shapes and weights for each beam with the TBC being forced/encouraged to inside of the segmented fields. The percentage of total MUs delivered to the largest area segments in each beam increased from 16.4% of the total MUs to 21.5%. The MU weight increased up to 20% by using TMTJ constrain. The DVHs for PTV and ORs, dose distributions and total MUs for plans with/without TMTJ constraints were very similar. Conclusion: The 4D tumor motion trajectory information can be used as a constraint in the Pinnacle DMPO to obtain tempospatially optimized IMRT plans. The method shows the potential to significantly reducing the dosimetric inaccuracies introduced by the interplay between organ motion and multileaf collimator (MLC) motion for IMRT.

SU-GG-T-112: Segment-Modulated Arc Radiation Therapy: Single Arc Inverse Planning with Binary Programming and Exact Leaf-Sequencing Algorithm

Purpose: The challenge of arc radiation therapy inverse planning mainly comes from the increased optimization problem size and the strong MLC constraints due to the fast gantry rotation. Many optimization algorithms have been proposed in the literature with different strengths and drawbacks while an ultimate solution is yet to be found. Method and materials: In this paper, we propose a novel inverse planning algorithm referred to as segment‐modulated arc radiation therapy (SMART). The optimization problem has a quadratic dose objective, and the decision variables include binary status (open or close) of each beamlet and the segment weight for each field. In the optimization process, each iterate is decomposed into the following steps: (1) A small number of (typically 36) binary MLC patterns are created by the binary simulated annealing algorithm, which are then used to generate trial aperture shapes for the 180 control points in the 360 degree arc; (2) A fast pattern‐decompose algorithm is then applied to generate an aperture for each of the 180 control points under the constraint of MLC hardware; (3) The dose distribution is calculated by using the apertures and the beamlet‐kernels and then the planning objective are evaluated; (4) Go to step 1 if the convergence condition is not met; Otherwise, save the plan. Results: The proposed approach was demonstrated using a pancreas case and a prostate case and compared with DAO method. Our results show that the method produces a highly conformai IMRT plan, which requires ∼ 3 minute to deliver. Conclusion: The derived plans achieve dose distributions equivalent or superior to the direct‐aperture optimization (DAO) based arc therapy treatment planning.

SU‐GG‐J‐48: An Online Replanning Method for Independently Moving Structures

Purpose: The current IGRT repositioning, based on rigid‐bady registration, fails to align organs with independent dislocation and deformation such as those in the abdomen. This work aims to extend a previously developed online replanning method to handle independent multiple organ movement. Methods and Materials: Daily CTs acquired during pancreatic cancer treatments using a respiratory gated CT‐on‐Rails (CTVision, Siemens) were used to test the method. Contours of the target and organs at risk (OAR) were generated on the daily CTs based on deformable registration with manual editing if necessary. A replanning method composed of a segment aperture morphing (SAM) and segment weight optimization (SWO) were applied. The SAM was applied separately on each structure (target and OARs), and the final aperture shape was formed by prioritizing individual aperture shapes. Each structure imposes specific penalties on leaf position deviations from their SAM values which mainly depends on the importance of the particular structure., Penalties for leaf opening vs. closing are different for target vs OAR. Conflict apertures are also detected automatically by SWO, which employs segment splitting along with an objective function scheme that updates the power of individual goals to prevent multiple trial and error runs. Plans for the current patient repositioning were generated for comparison. Results: The mean doses of stomach and duodenum for repositioning plans are increased by 66% and 10% from their planning values, which are reduced to 5% and 1% for the adaptive plans based on modified by SAM without compromising the target coverage. SWO further improved the plan quality resulting in the final plans that are comparable to the original plan. The SAM and SWO algorithms for multiple structures can be executed within 10 min. Conclusion: The modified SAM+SWO algorithms that can handle multiple independent organ motion and deformation can be implemented for online adaptive replanning.

SU-GG-T-22: An Adaptive Strategy for Simultaneous Treatment of the Prostate and Pelvic Lymph Nodes

Purpose: Certain prostate cancer patients are treated with simultaneous irradiation of pelvic lymph nodes and the prostate gland. One common method to compensate for prostate motion is to shift the patient based on implanted prostate markers. However, the pelvic lymph nodes move little relative to the bony anatomy. In this study, we evaluate an adaptive strategy designed to ensure that radiation is delivered accurately to both the prostate and the pelvic lymph nodes. Materials and Methods:Treatment plans devised using clinical planning CT data and structures were optimized to deliver 50 Gy to the expanded prostate and seminal vesicles and 45 Gy to the lymph nodes. We used megavoltage conebeam CT data acquired during treatment to create a model of daily anatomical variations. The treatment plan and structures were transferred to this new model. The prostate, seminal vesicles, bladder, and rectum structures were shifted according to the position of prostate markers. The lymph node volumes were transferred according to the bony anatomy. In total, four plans were prepared: 1) the original plan 2) original plan shifted to match prostate motion 3) aperture morphing to compensate for prostate motion, and 4) aperture morphing followed by segment weight optimization. Results: When the isocenter is shifted to track the prostate, the prostate received the correct dose while lymph nodes were underdosed. In one example, we found that D‐95% reduced to 3500 cGy. Aperture morphing alone was not sufficient to deliver the correct dose to both the lymph nodes and prostate. However, aperture morphing followed by segment weight optimization improved coverage of the nodes and prostate. Conclusions: Our results demonstrate that aperture morphing combined with segment weight optimization is an adaptive strategy that can be used to compensate for the independent motions of the lymph nodes and prostate. Research sponsored by Prowess Inc.

Skeletal muscle catabolism in trinitrobenzene sulfonic acid–induced murine colitis

The present study determined whether the muscle atrophy produced by colitis is associated with altered rates of muscle protein synthesis or degradation, as well as the potential role of the local (eg, muscle) insulin-like growth factor (IGF) system and muscle-specific ubiquitin E3 ligases atrogin-1 and MuRF1 in mediating altered muscle protein balance. Colitis was induced in C57BL/6 mice by intrarectal administration of trinitrobenzene sulfonic acid (TNBS), and blood and tissues were collected on day 10. Mice with inflammatory bowel disease demonstrated reduced skeletal muscle mass and protein content, whereas colonic segment weight and gross damage score were both increased in mice with colitis, compared with time-matched control values. There was no change in muscle protein synthesis in mice with inflammatory bowel disease; but there was an increased protein breakdown (45%), proteasome activity (85%), and messenger RNA (mRNA) expression for atrogin-1 and MuRF1 (200%-300%) in muscle. These changes were associated with a reduction in liver (but not muscle) IGF-I mRNA as well as a reduction in both total and free IGF-I in the blood. Colitis decreased the hepatic content of IGF binding protein (IGFBP)–3 mRNA by 40% and increased IGFBP-1 mRNA by 100%. In contrast, colitis did alter IGFBP mRNAs in muscle. The tumor necrosis factor– α, interleukin-6, and nitric oxide synthase 2 mRNA content of both liver and skeletal muscle was increased in TNBS-treated mice; and plasma tumor necrosis factor– α and interleukin-6 concentrations were also elevated. These data suggest that TNBS-induced colitis is independent of a change in muscle protein synthesis but dependent on stimulation of protein degradation via increased expression of muscle-specific atrogenes, which may be mediated in part by the reduction in circulating concentration of IGF-I and the concomitant increase in inflammatory mediators observed in the blood and muscle per se.

Online Adaptive Replanning Method for Prostate Radiotherapy

To report the application of an adaptive replanning technique for prostate cancer radiotherapy (RT), consisting of two steps: (1) segment aperture morphing (SAM), and (2) segment weight optimization (SWO), to account for interfraction variations. The new "SAM+SWO" scheme was retroactively applied to the daily CT images acquired for 10 prostate cancer patients on a linear accelerator and CT-on-Rails combination during the course of RT. Doses generated by the SAM+SWO scheme based on the daily CT images were compared with doses generated after patient repositioning using the current planning target volume (PTV) margin (5 mm, 3 mm toward rectum) and a reduced margin (2 mm), along with full reoptimization scans based on the daily CT images to evaluate dosimetry benefits. For all cases studied, the online replanning method provided significantly better target coverage when compared with repositioning with reduced PTV (13% increase in minimum prostate dose) and improved organ sparing when compared with repositioning with regular PTV (13% decrease in the generalized equivalent uniform dose of rectum). The time required to complete the online replanning process was 6 +/- 2 minutes. The proposed online replanning method can be used to account for interfraction variations for prostate RT with a practically acceptable time frame (5-10 min) and with significant dosimetric benefits. On the basis of this study, the developed online replanning scheme is being implemented in the clinic for prostate RT.

Synthesis and characterization of amphiphilic pluronic (F68)‐1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphoethanolamine copolymers and their micelles as a drug carrier

AbstractA new Pluronic (F68)‐1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphoethanolamine (DPPE) (Pluronic (F68)–DPPE) copolymer was synthesized with Pluronic (F68) and DPPE. The chemical structure and physical properties of copolymers were determined by FTIR, 1H NMR, 13C NMR, 31P NMR, and TGA. Environmental scanning electron microscopy, fluorescence spectroscopy, and dynamic light scattering method confirmed the formation of copolymeric micelles of Pluronic (F68)‐DPPE. To estimate the feasibility as novel drug carriers, the copolymer micelles were prepared by the phase separation dialysis method. Amphotericin B as a lipophilic model drug was incorporated into copolymeric micelles and the drug release behavior was investigated. It was found that the chemical composition of the micelle was a key factor in controlling micelles size, drug‐loading content, and drug release behavior. As DPPE segment weight ratio increased, the micelle size and drug‐loading content increased, and the drug release rate decreased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Polymethylene‐b‐polystyrene diblock copolymer: Synthesis, property, and application

AbstractThe design and synthesis of well‐defined polymethylene‐b‐polystyrene (PM‐b‐PS, Mn = 1.3 × 104–3.0 × 104 g/mol; Mw/Mn (GPC) = 1.08–1.18) diblock copolymers by the combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was successfully achieved. The 1H NMR spectrum and GPC traces of PM‐b‐PS indicated the successful extension of PS segment on the PM macroinitiator. The micellization behavior of such diblock copolymers in tetrahydrofuran were characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) techniques. The average aggregate sizes of PM‐b‐PS diblock copolymers with the same length of PM segment in tetrahydrofuran solution (1.0 mg mL−1) increases from 104.2 nm to 167.7 nm when the molecular weight of PS segment increases. The spherical precipitated aggregates of PM‐b‐PS diblock copolymers with an average diameter of 600 nm were observed by AFM. Honeycomb porous films with the average diameter of 3.0 μm and 6.0 μm, respectively, were successfully fabricated using the solution of PM‐b‐PS diblock copolymers in carbon disulfide via the breath‐figure (BF) method under a static humid condition. The cross‐sections of low density polyethylene (LDPE)/polystyrene (PS)/PM‐b‐PS and LDPE/polycarbonate (PC)/PM‐b‐PS blends were observed by scanning electron microscope and reveal that the PM‐b‐PS diblock copolymers are effective compatilizers for LDPE/PS and LDPE/PC blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1894–1900, 2010

4SC-101, a novel immunosuppressive drug, inhibits IL-17 and attenuates colitis in two murine models of inflammatory bowel disease†

Dihydroorotate dehydrogenase (DHODH) is a key enzyme involved in pyrimidine biosynthesis. DHODH is a known target for the treatment of autoimmune diseases. 4SC-101 is a novel immunosuppressive drug that inhibits DHODH. A goal of our study was to examine the in vitro effects of 4SC-101 on IL-17 production by mononuclear cells. In addition, we evaluated the efficacy of 4SC-101 against acute TNBS (2,4,6-tritrobenzene sulfonic acid) and chronic dextran sodium sulfate (DSS)-induced colitis in mice. Peripheral blood mononuclear cells (PBMCs) from healthy human donors were used to evaluate cellular proliferation and cytokine (IL-17, TNF-α) production. The oral effects of 4SC-101 (100 or 200 mg/kg) were examined following induction of chronic colitis by the administration of 3% DSS (4 cycles) to Balb/c mice. Morphometric and histological indices of colitis were evaluated as indicators of drug efficacy. 4SC-101 was also administered for 6 days after the intracolonic administration of TNBS (20 mg in 50% ethanol) to female Balb/c mice. The colons were analyzed for overall macroscopic damage, ulceration, total length, distal segment weight, MPO activity, and histological pathology as indicators for the effectiveness of 4SC-101. In vitro, 4SC-101 is a potent inhibitor of human DHODH, inhibits lymphocyte proliferation, and uniquely blocks phytohemagglutinin-stimulated IL-17 production by lymphocytes. In vivo, oral administration of 4SC-101 effectively improved both chronic DSS and acute TNBS colitis in mice. In these colitis models the overall efficacy profile of 4SC-101 was similar to that of dexamethasone. 4SC-101 is a novel immunosuppressive drug with excellent potential for the treatment of intestinal inflammation.

Large-pore ordered mesoporous carbons with tunable structures and pore sizes templated from poly(ethylene oxide)- b-poly(methyl methacrylate)

Ordered mesoporous carbons (OMCs) with possible face-centered cubic (space group F m 3 ¯ m ) and 2-D hexagonal ( p6 mm) symmetries have been successfully synthesized by using lab-made poly(ethylene oxide)- block-poly(methyl methacrylate) diblock polymers (PEO- b-PMMA) with different PEO/PMMA ratios as a template. The synthesis process undergoes an evaporation induced self-assembly (EISA) at 100 °C by using low-molecular weight phenolic resol as a carbon source and tetrahydrofuran (THF) as the solvent. The atom transfer radical polymerization (ATRP) method was used to prepare the diblock copolymers with different molecular weight and compositions of PEO and PMMA segments by simply changing the PEO initiator and polymerization time. For the first time, we have obtained OMCs with hexagonal p6 mm symmetry and large pore size (8.6–12.1 nm) by using PEO- b-PMMA with long PMMA segment as the templates. Notably, the pore size of the ordered mesoporous carbons can be tuned in the range of 8.6–22.0 nm by slightly adjusting the hydrophobic PMMA length of the template or adding desired amount of PMMA homopolymer as a pore expander. Additionally, it is found that the pore wall thickness of OMCs with possible face-centered cubic symmetry can be adjusted from 8.1 to 10.4 nm by simply increasing the weight ratio of resol to the template ( R w).

Thermoplastic elastomers with multi-walled carbon nanotubes: Influence of dispersion methods on morphology

PBT-block-PTMO thermoplastic elastomers derived from dimethyl terephthalate (DMT), 1,4-butanediol(BD) and poly(tetramethylene glycol) (PTMG) were synthesized in the presence of oxidized multi-walled carbon nanotubes (MWCNTs) by a two-stage process involving transesterification and in situ polycondensation. Two procedures were applied to nanotubes in the polymer matrices were used. In procedure 1, nanotubes were dispersed in DMT + BD before the transesterification, while in procedure 2 nanotubes were dispersed in PTMG after transesterification. The mole ratio of the starting components was selected to produce copolymers with a constant hard to soft segment weight ratio of 45:55. Characterization of the new nanocomposites was performed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), small- and wide-angle X-ray scattering (SAXS/WAXS). A better nanotube dispersion can be achieved when oxidized MWCNTs are added to the DMT + BD monomers before transesterification (procedure 1). Oxidized MWCNTs exhibit strong interfacial adhesion to the polymer matrix for both procedures.