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Membrane Formation (membrane + formation)
Selected AbstractsA Self-assembly Route for Double Bilayer Lipid Membrane FormationCHEMPHYSCHEM, Issue 3 2010Xiaojun Han Dr. Biomembranes: A new method of forming double bilayer lipid membranes uses NHS/EDC chemistry to link adjacent bilayers, both of which remain fluid. This approach provides a novel platform for the study of biomembranes, in which the components of the upper membrane are shielded from the solid substrate by a second membrane (see figure); and for studying more complex membrane protein systems which span double lipid bilayers. [source] The pathology of bronchointerstitial pneumonia in young foals associated with the first outbreak of equine influenza in AustraliaEQUINE VETERINARY JOURNAL, Issue 3 2008J. C. PATTERSON-KANE Summary Objectives: The aim of this study was to describe post mortem lesions in EIV-infected foals. Methods: Post mortem examinations were conducted on 11 young foals (age 2,12 days) submitted to the Scone Veterinary Hospital, New South Wales, Australia over a 2-month period in 2007. The foals had presented with or developed fatal pneumonia, and were known or suspected to be EIV-positive. Equine influenza virus nucleic acid was detected in tissue specimens using an influenza A group reactive real-time reverse transcriptase PCR assay. Results: Grossly there was diffuse or extensive pulmonary consolidation. Histological changes included: bronchiolar and alveolar necrosis; neutrophilic infiltration; hyaline membrane formation; and hyperplasia and squamous metaplasia of airway epithelium. Tissues for 10 foals were EIV-positive, with a positive nasal swab from the remaining animal. Conclusions: This is the first detailed pathological description of bronchointerstitial pneumonia associated with EIV infection in young foals. It is also the first series of such cases in which a causative agent has consistently been detected. Potential relevance: Given the findings in this outbreak, and a previous outbreak in the UK in 1965 involving a similarly naive population, veterinary clinicians and pathologists should be aware that EIV can cause fatal bronchointerstitial pneumonia in young foals that do not have maternal immunity. The lesions did not differ from those previously reported in foals of various ages with bronchointerstitial pneumonia of other or undefined causes, indicating that this is most likely to be a stereotypical response to a variety of insults. Therefore, tissue specimens should be obtained from cases of pneumonia in young foals for virological and bacteriological testing. Reasons for performing study: The first outbreak of equine influenza virus (EIV) infection was confirmed in Australia in 2007. Some EIV-positive young foals died with broncho-interstitial pneumonia, a rare disease process in this age group that is often postulated to be caused by viral infection. [source] Chemical modification of polyethersulfone nanofiltration membranes: A reviewJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009B. Van der Bruggen Abstract Polysulfone (PS) and poly(ether)sulfone (PES) are often used for synthesis of nanofiltration membranes, due to their chemical, thermal, and mechanical stability. The disadvantage for applying PS/PES is their high hydrophobicity, which increases membrane fouling. To optimize the performance of PS/PES nanofiltration membranes, membranes can be modified. An increase in membrane hydrophilicity is a good method to improve membrane performance. This article reviews chemical (and physicochemical) modification methods applied to increase the hydrophilicity of PS/PES nanofiltration membranes. Modification of poly(ether)sulfone membranes in view of increasing hydrophilicity can be carried out in several ways. Physical or chemical membrane modification processes after formation of the membrane create more hydrophilic surfaces. Such modification processes are (1) graft polymerization that chemically attaches hydrophilic monomers to the membrane surface; (2) plasma treatment, that introduces different functional groups to the membrane surface; and (3) physical preadsorption of hydrophilic components to the membrane surface. Surfactant modification, self-assembly of hydrophilic nanoparticles and membrane nitrification are also such membrane modification processes. Another approach is based on modification of polymers before membrane formation. This bulk modification implies the modification of membrane materials before membrane synthesis of the incorporation of hydrophilic additives in the membrane matrix during membrane synthesis. Sulfonation, carboxylation, and nitration are such techniques. To conclude, polymer blending also results in membranes with improved surface characteristics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Identification of Novel Regulators Associated With Early-Phase Osteoblast Differentiation,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2004Diana S de Jong Abstract Key regulatory components of the BMP-induced osteoblast differentiation cascade remain to be established. Microarray and subsequent expression analyses in mice identified two transcription factors, Hey1 and Tcf7, with in vitro and in vivo expression characteristics very similar to Cbfa1. Transfection studies suggest that Tcf7 modulates BMP2-induced osteoblast differentiation. This study contributes to a better definition of the onset of BMP-induced osteoblast differentiation. Introduction: Elucidation of the genetic cascade guiding mesenchymal stem cells to become osteoblasts is of extreme importance for improving the treatment of bone-related diseases such as osteoporosis. The aim of this study was to identify regulators of the early phases of bone morphogenetic protein (BMP)2-induced osteoblast differentiation. Materials and Methods: Osteoblast differentiation of mouse C2C12 cells was induced by treatment with BMP2, and regulation of gene expression was studied during the subsequent 24 h using high-density microarrays. The regulated genes were grouped by means of model-based clustering, and protein functions were assigned. Real-time quantitative RT-PCR analysis was used to validate BMP2-induced gene expression patterns in C2C12 cells. Osteoblast specificity was studied by comparing these expression patterns with those in C3H10T1/2 and NIH3T3 cells under similar conditions. In situ hybridization of mRNA in embryos at embryonic day (E)14.5 and E16.5 of gestation and on newborn mouse tails were used to study in vivo expression patterns. Cells constitutively expressing the regulated gene Tcf7 were used to investigate its influence on BMP-induced osteoblast differentiation. Results and Conclusions: A total of 184 genes and expressed sequence tags (ESTs) were differentially expressed in the first 24 h after BMP2 treatment and grouped in subsets of immediate early, intermediate early, and late early response genes. Signal transduction regulatory factors mainly represented the subset of immediate early genes. Regulation of expression of these genes was direct, independent of de novo protein synthesis and independent of the cell type studied. The intermediate early and late early genes consisted primarily of genes related to processes that modulate morphology, basement membrane formation, and synthesis of extracellular calcified matrix. The late early genes require de novo protein synthesis and show osteoblast specificity. In vivo and in vitro experiments showed that the transcription factors Hey1 and Tcf7 exhibited expression characteristics and cell type specificity very similar to those of the osteoblast specific transcription factor Cbfa1, and constitutive expression of Tcf7 in C2C12 cells differentially regulated osteoblast differentiation marker genes. [source] Acute inorganic mercury vapor inhalation poisoningPATHOLOGY INTERNATIONAL, Issue 3 2000Sigeyuki Asano Abstract Mercury contamination is a serious environmental problem worldwide. Two primary sources of contamination are dumping of large quantities of inorganic mercury and exposure in the mining industry. Although the actual fatal level of mercury vapor is not known, exposure to more than 1,2 mg/m3 of elemental mercury vapor (Hg0) for a few hours causes acute chemical bronchiolitis and pneumonitis. Two hours after exposure, lung injury appears as hyaline membrane formation, and finally, extensive pulmonary fibrosis occurs. Clinical findings correlate with the duration of exposure, the concentration of mercury, and the survival time after exposure. There is no correlation between pathological findings and the concentration of mercury in the tissues. Necrosis of proximal convoluted tubules may be attributed to the disruption of the enzyme systems of Hg2+ -sulfhydryl compounds. Metallothionein protein (MT), induced by the accumulation of Hg2+ in the kidneys, may play an important role in detoxication after it forms a non-toxic Hg2+ -MT compound. Despite the deposition of mercury in the brain, compared with organic mercury, inorganic mercury did not seem to damage the neurons. Drugs such as chelating agents and corticosteroids appear to effectively decrease the inflammation and delay pulmonary fibrosis. [source] Mixed matrix membrane materials with glassy polymers.POLYMER ENGINEERING & SCIENCE, Issue 7 2002Part Analysis presented in Part 1 of this paper indicated the importance of optimization of the transport properties of the interfacial region to achieve ideal mixed matrix materials. This insight is used in this paper to guide mixed matrix material formation with more conventional gas separation polymers. Conventional gas separation materials are rigid, and, as seen earlier, lead to the formation of an undesirable interphase under conventional casting techniques. We show in this study that if flexibility can be maintained during membrane formation with a polymer that interacts favorably with the sieve, successful mixed matrix materials result, even with rigid polymeric materials. Flexibility during membrane formation can be achieved by formation of films at temperatures close to the glass transition temperature of the polymer. Moreover, combination of chemical coupling and flexibility during membrane formation produces even more significant improvements in membrane performance. This approach leads to the formation of mixed matrix material with transport properties exceeding the upper bound currently achieved by conventional membrane materials. Another approach to form successful mixed matrix materials involves tailoring the interface by use of integral chemical linkages that are intrinsically part of the chain backbone. Such linkages appear to tighten the interface sufficiently to prevent "nonselective leakage" along the interface. This approach is demonstrated by directly bonding a reactive polymer onto the sieve surface under proper processing conditions. [source] Preparation of oily core polyamide microcapsules via interfacial polycondensation,POLYMER INTERNATIONAL, Issue 4 2003L Soto-Portas Abstract Microcapsules obtained by interfacial polycondensation from an original system based on the polyaddition of specific di- or polyamines and more classical acyl chloride molecules were studied. The originality of the system lies in the fact that the encapsulated agent is the internal phase allowing its incorporation without an organic solvent, which is an advantage from the point of view of environmental protection. Once the optimal parameters of the emulsion were determined, the membrane formation was studied by optimizing the emulsification and reaction times in relation to simultaneous acyl chloride hydrolysis. The microcapsules were obtained by interfacial polycondensation between an excess of amine functions (diamine and diethylenetriamine) and acyl chloride (sebacoyl chloride and 1,3,5-benzene tricarbonyl trichloride) from an oil-in-water emulsion in the presence of 88% hydrolyzed poly(vinyl alcohol) as a surfactant. Various formulations in terms of COCl concentration, crosslinking agent concentration, excess of amine functions, emulsification and reaction times were prepared. The hydrolysis of acyl halide functions is the main parameter which influences the growth of the membrane. The increase in acyl chloride function concentration allows compensation for that lost by hydrolysis, and increases the encapsulation yield to about 90%. The degree of crosslinking of the membrane was controlled in order to minimize the subsequent release of oil by the addition of trifunctional monomers. An optimal formulation was developed offering high encapsulation yield and optimal elastic behaviour. Almost spherical capsules, with a membrane thickness of approximately 500,nm, relatively smooth internal walls and crumpled external walls, were observed by scanning electron microscopy. © 2003 Society of Chemical Industry [source] SARS: clinical virology and pathogenesisRESPIROLOGY, Issue 2003John NICHOLLS Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus, called the SARS coronavirus (SARS-CoV). Over 95% of well characterized cohorts of SARS have evidence of recent SARS-CoV infection. The genome of SARS-CoV has been sequenced and it is not related to any of the previously known human or animal coronaviruses. It is probable that SARS-CoV was an animal virus that adapted to human-human transmission in the recent past. The virus can be found in nasopharyngeal aspirate, urine and stools of SARS patients. Second generation reverse transcriptase polymerase chain reaction assays are able to detect SARS-CoV in nasopharyngeal aspirates of approximately 80% of patients with SARS within the first 3 days of illness. Seroconversion for SARS-CoV using immunofluorescence on infected cells is an excellent method of confirming the diagnosis, but antibody responses only appear around day 10 of the illness. Within the first 10 days the histological picture is that of acute phase diffuse alveolar damage (DAD) with a mixture of inflammatory infiltrate, oedema and hyaline membrane formation. Desquamation of pneumocytes is prominent and consistent. After 10 days of illness the picture changes to one of organizing DAD with increased fibrosis, squamous metaplasia and multinucleated giant cells. The role of cytokines in the pathogenesis of SARS is still unclear. [source] Intravitreal anti-vascular endothelial growth factor therapy with bevacizumab for tuberous sclerosis with macular oedemaACTA OPHTHALMOLOGICA, Issue 3 2010Wataru Saito Abstract. Purpose:, To describe two patients with macular oedema secondary to tuberous sclerosis complex (TSC) who were treated with intravitreal bevacizumab injection. Methods:, Interventional case reports. Bevacizumab 1.25 mg was injected into the vitreous of two patients with TSC-associated macular oedema / exudative retinal detachment. Vascular endothelial growth factor (VEGF) concentration in the vitreous fluid was measured by enzyme-linked immunosorbent assay (ELISA) in one of these patients. Results:, Patient 1: a 22-year-old woman with TSC was diagnosed as having multiple retinal hamartomas in both eyes. Eleven years later, the patient developed macular oedema with epiretinal membrane formation in the right eye. The patient underwent pars-plana vitrectomy with retinal photocoagulation for retinal tumours. VEGF concentration in the vitreous fluid was high compared to that in patients without retinal vascular diseases. Recurrent macular oedema disappeared by intravitreal injection of bevacizumab. Patient 2: a 32-year-old woman with TSC-associated retinal hamartoma, temporally showing macular exudative retinal detachment, developed neovascularization originated from the tumour. By intravitreal bevacizumab injection, the tumour size reduced markedly with regression of neovascularization. Conclusion:, These results suggest that VEGF derived from retinal hamartomas causes macular oedema associated with TSC. Intravitreal injections of bevacizumab may be a useful therapeutic option for macular oedema secondary to TSC. [source] Is there still a place for vitrectomy in the treatment of macular edema due to venous occlusion ?ACTA OPHTHALMOLOGICA, Issue 2009CJ POURNARAS Purpose Persistent macular edema (ME) is the main cause of poor visual outcome in either non-ischemic BRVO or CRVO. Among multiples treatment approaches, vitreoretinal surgery with the goal to achieve the recanalisation of the occluded vessels and/or the resolution of ME, were proposed. Methods Vitrectomy with peeling of the posterior hyaloid and/or the internal limiting membrane,asociated to intravitreal (IVT) triamcinolone , neurotomy, sheathotomy, intravascular rtPA injection were studied in numerous nonrandomized cases series. Results Pars plana vitrectomy has been shown to reduce macular oedema and restore the normal foveal contour without significant change in best corrected visual acuity. In contrast, visual improvement occurs after vitrectomy for vitreous haemorrhage, epiretinal membrane formation and retinal detachment complicating BRVO. Evidence to date does not support any therapeutic benefit from radial optic neurotomy, optic nerve decompression, arteriovenous crossing sheathotomy or intravascular rtPA. Vitrectomy combined with IVT triamcinolone, induces a ME decrease rapidly and durably, without any improvement in visual acuity. Conclusion Vitrectomy with IVT triamcinolne seems to have a more durable effect than IVT triamcinolone alone.Vitrectomy, A-V sheathotomy combined with intravenous t-PA may offer benefits in BRVO. Despite uncertainty and open questions, surgical interventions are likely to be a therapeutic option for RVO in the future. Randomized and controlled studies are needed to confirm these results and to compare them to the natural course of the disease. [source] Boston type I in pediatric patientsACTA OPHTHALMOLOGICA, Issue 2009J AQUAVELLA Purpose To present a retrospective review of keratoprosthetic implantation and retention in patients with congenital corneal opacities. Methods Pediatric patients younger than seven years old, the average age of permanent visual loss from understimulation of the visual cortex, were selected from a single center Boston Type I keratoprosthesis database and categorized by 1) primary diagnosis, 2) short-term visual outcome, and 3) post-operative complications. Results Seventeen patients, with an age range of 41 days up to 6 years, were selected from a database of over one hundred and forty patients. Six had a primary diagnosis of sclerocornea and eleven had Peter's anomaly. Visual outcome after one year improved in fourteen of the patients, with patients who previously could not detect light to subsequently being able to fixate and follow or even read allen cards. The remaining three patients showed no improvement in visual acuity but also no worsening from their baseline condition. In terms of post-operative complications of the optic, two had retroprosthetic membrane formation, and another patient required replacement of the keratoprosthesis due to phthisis and optic melting. From a retinal standpoint, four patients had retinal detachments. There were no cases of choroidal hemorrhaging or hypotony in these patients. Conclusion Based on visual outcome, the Boston Type I keratoprosthesis is a safe and effective procedure for patients with congenital corneal opacities. With great retention, the artificial cornea is a viable option for prevention of amblyopia. Due to comorbidities such as congenital cataracts, congenital glaucoma, and retinal detachments, it is crucial to have glaucoma and vitreo-retinal surgeons on hand when managing and implanting keratoprosthesis in a pediatric population. [source] Dense membrane formation after combined phacoemulsification,trabeculectomy surgeryCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2005Colin CK Chan MB BS(Hons) Abstract A case is reported of formation of a dense intraocular membrane following combined phacoemulsification,trabeculectomy surgery. The membrane might have originated from a loose piece of pigment epithelium or might have resulted from dense pigment deposition on a postoperative pupillary membrane. Postoperative membranes have been reported particularly after combined procedures. A combination of intensive topical dexamethasone, homatropine and a Nd:YAG laser was used to speed resolution of the membrane. [source] | |||||||||||||