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Sample records for microsphere derived cerebral

  1. Radioactive microsphere study of cerebral blood flow under acceleration. Technical report

    SciTech Connect

    Greenlees, K.J.; Yoder, J.E.; Toth, D.M.; Oloff, C.M.; Karl, A.

    1980-11-01

    A study using radioactive microspheres for the investigation of cerebral blood flow during acceleration is described. Details of a technique for the blunt dissection of cerebral tissues are included. Results of flow studies at 3 and 5 G sub z acceleration stress indicate there is no selective regional preservation of cerebral tissue. (Author)

  2. Biomass Vanillin-Derived Polymeric Microspheres Containing Functional Aldehyde Groups: Preparation, Characterization, and Application as Adsorbent.

    PubMed

    Zhang, Huanyu; Yong, Xueyong; Zhou, Jinyong; Deng, Jianping; Wu, Youping

    2016-02-01

    The contribution reports the first polymeric microspheres derived from a biomass, vanillin. It reacted with methacryloyl chloride, providing monomer vanillin methacrylate (VMA), which underwent suspension polymerization in aqueous media and yielded microspheres in high yield (>90 wt %). By controlling the N2 bubbling mode and by optimizing the cosolvent for dissolving the solid monomer, the microspheres were endowed with surface pores, demonstrated by SEM images and mercury intrusion porosimetry measurement. Taking advantage of the reactive aldehyde groups, the microspheres further reacted with glycine, thereby leading to a novel type of Schiff-base chelating material. The functionalized microspheres demonstrated remarkable adsorption toward Cu(2+) (maximum, 135 mg/g) which was taken as representative for metal ions. The present study provides an unprecedented class of biobased polymeric microspheres showing large potentials as adsorbents in wastewater treatment. Also importantly, the reactive aldehyde groups may enable the microspheres to be used as novel materials for immobilizing biomacromolecules, e.g. enzymes. PMID:26752344

  3. Biomass Vanillin-Derived Polymeric Microspheres Containing Functional Aldehyde Groups: Preparation, Characterization, and Application as Adsorbent.

    PubMed

    Zhang, Huanyu; Yong, Xueyong; Zhou, Jinyong; Deng, Jianping; Wu, Youping

    2016-02-01

    The contribution reports the first polymeric microspheres derived from a biomass, vanillin. It reacted with methacryloyl chloride, providing monomer vanillin methacrylate (VMA), which underwent suspension polymerization in aqueous media and yielded microspheres in high yield (>90 wt %). By controlling the N2 bubbling mode and by optimizing the cosolvent for dissolving the solid monomer, the microspheres were endowed with surface pores, demonstrated by SEM images and mercury intrusion porosimetry measurement. Taking advantage of the reactive aldehyde groups, the microspheres further reacted with glycine, thereby leading to a novel type of Schiff-base chelating material. The functionalized microspheres demonstrated remarkable adsorption toward Cu(2+) (maximum, 135 mg/g) which was taken as representative for metal ions. The present study provides an unprecedented class of biobased polymeric microspheres showing large potentials as adsorbents in wastewater treatment. Also importantly, the reactive aldehyde groups may enable the microspheres to be used as novel materials for immobilizing biomacromolecules, e.g. enzymes.

  4. Microspheres

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Vital information on a person's physical condition can be obtained by identifying and counting the population of T-cells and B-cells, lymphocytes of the same shape and size that help the immune system protect the body from the invasion of disease. The late Dr. Alan Rembaum developed a method for identifying the cells. The method involved tagging the T-cells and B-cells with microspheres of different fluorescent color. Microspheres, which have fluorescent dye embedded in them, are chemically treated so that they can link with antibodies. With the help of a complex antibody/antigen reaction, the microspheres bind themselves to specific 'targets,' in this case the T-cells or B-cells. Each group of cells can then be analyzed by a photoelectronic instrument at different wavelengths emitted by the fluorescent dyes. Same concept was applied to the separation of cancer cells from normal cells. Microspheres were also used to conduct many other research projects. Under a patent license Magsphere, Inc. is producing a wide spectrum of microspheres on a large scale and selling them worldwide for various applications.

  5. Simultaneous measurements of cerebral blood flow by the xenon/CT method and the microsphere method. A comparison

    SciTech Connect

    Gur, D.; Yonas, H.; Jackson, D.L.; Wolfson, S.K. Jr.; Rockette, H.; Good, W.F.; Cook, E.E.; Arena, V.C.; Willy, J.A.; Maitz, G.S.

    1985-10-01

    Simultaneous measurements of cerebral blood flow have been performed in baboons to assess the correlation between the acute and invasive nondiffusible microsphere technique and the noninvasive xenon-enhanced CT method. Blood flows in small tissue volumes (approximately 1 cm3) were directly compared. The results of these studies demonstrate a statistically significant association between the two methods (P less than .001). Similar correlations were obtained by both the Kendall tau (tau) and the Spearman (r) methods. The problems and limitations of such correlations are discussed.

  6. Radiosterilisation of indomethacin PLGA/PEG-derivative microspheres: protective effects of low temperature during gamma-irradiation.

    PubMed

    Fernández-Carballido, Ana; Puebla, Patricia; Herrero-Vanrell, Rocío; Pastoriza, Pilar

    2006-04-26

    Currently, gamma-irradiation seems to be a good method for sterilising drug delivery systems made from biodegradable polymers. The gamma-irradiation of microspheres can cause several physicochemical changes in the polymeric matrix. These modifications are affected by the temperature, irradiation dose and nature of the encapsulated drug and additives. This study has aimed to evaluate the influence of temperature during the sterilisation process by gamma irradiation in indomethacin PLGA microspheres including a PEG-derivative. Microspheres were prepared by the solvent evaporation method from o/w emulsion and were then exposed to gamma-irradiation. A dose of 25 kGy was used to ensure effective sterilisation. Some microspheres were sterilised with dry ice protection that guaranteed a low temperature during the process whilst others were sterilised without such dry ice protection. The effects of gamma-irradiation on the characteristics of non-loaded PLGA/PEG-derivative and indomethacin loaded PLGA/PEG-derivative microspheres with and without protection were studied. Non-protected microspheres showed changes in their morphological surface, polymer glass transition temperature, molecular weight and release rate of indomethacin after sterilisation. However, microspheres sterilised with protection did not show significant differences after gamma-irradiation exposure. The sterilisation method was satisfactory when the indomethacin loaded microspheres including a PEG-derivative were exposed to gamma-irradiation at low temperature.

  7. A comparison of measurements of cerebral blood flow in the rabbit using laser Doppler spectroscopy and radionuclide labelled microspheres.

    PubMed

    Eyre, J A; Essex, T J; Flecknell, P A; Bartholomew, P H; Sinclair, J I

    1988-02-01

    Laser Doppler spectroscopy has been evaluated for the measurement of cerebral blood flow (CBF) by correlation with simultaneous measurements by radionuclide labelled microspheres. The experimental procedures were carried out on five anaesthetised rabbits. The cortical tissue was exposed by means of a small burr hole and illuminated by a helium neon laser (632.8 nm). Reflected light was detected using a silicon photodiode, and CBF was calculated continuously from the power of the frequency weighted Doppler spectrum in the reflected light. Three successive measurements of CBF were made using the microsphere technique. Following an initial baseline measurement, CBF was increased by an infusion of metaraminol and then reduced by controlled haemorrhage. Laser Doppler spectroscopy provided continuous monitoring of blood flow fluctuations and during the haemorrhage it was possible to demonstrate CBF autoregulation until the mean blood pressure fell below 6.7 kPa (50 mmHg). A regression analysis was performed between the simultaneous CBF measurements from the two techniques using a least squares best fit straight line analysis (r = 0.92, P less than 0.001). It was concluded that the flow computed from laser Doppler spectroscopy varied linearly with CBF and offers the unique advantage of continuous and instantaneous measurements even during nonsteady state flow.

  8. Intracardiac echocardiography guided transeptal catheter injection of microspheres for assessment of cerebral microcirculation in experimental models.

    PubMed

    Bellapart, Judith; Dunster, Kimble R; Diab, Sara; Platts, David G; Raffel, Christopher; Gabrielian, Levon; Maybauer, Marc O; Barnett, Adrian; Boots, Robert James; Fraser, John F

    2013-01-01

    The use of microspheres for the determination of regional microvascular blood flow (RMBF) has previously used different approaches. This study presents for the first time the intracardiac injection of microspheres using transeptal puncture under intracardiac echocardiography guidance. Five Merino sheep were instrumented and cardiovascularly supported according to local guidelines. Two catheter sheaths into the internal jugular vein facilitated the introduction of an intracardiac probe and transeptal catheter, respectively. Five million colour coded microspheres were injected into the left atrium via this catheter. After euthanasia the brain was used as proof of principle and the endpoint for determination of microcirculation at different time points. Homogeneous allocation of microspheres to different regions of the brain was found over time. Alternate slices from both hemispheres showed the following flow ranges: for slice 02; 0.57-1.02 mL/min/g, slice 04; 0.45-1.42 mL/min/g, slice 06; 0.35-1.87 mL/min/g, slice 08; 0.46-1.77 mL/min/g, slice 10; 0.34-1.28 mL/min/g. A mixed effect regression model demonstrated that the confidence interval did include zero suggesting that the apparent variability intra- and intersubject was not statistically significant, supporting the stability and reproducibility of the injection technique. This study demonstrates the feasibility of the transeptal injection of microspheres, showing a homogeneous distribution of blood flow through the brain unchanged over time and has established a new interventional model for the measurement of RMBF in ovine models.

  9. Intracardiac echocardiography guided transeptal catheter injection of microspheres for assessment of cerebral microcirculation in experimental models.

    PubMed

    Bellapart, Judith; Dunster, Kimble R; Diab, Sara; Platts, David G; Raffel, Christopher; Gabrielian, Levon; Maybauer, Marc O; Barnett, Adrian; Boots, Robert James; Fraser, John F

    2013-01-01

    The use of microspheres for the determination of regional microvascular blood flow (RMBF) has previously used different approaches. This study presents for the first time the intracardiac injection of microspheres using transeptal puncture under intracardiac echocardiography guidance. Five Merino sheep were instrumented and cardiovascularly supported according to local guidelines. Two catheter sheaths into the internal jugular vein facilitated the introduction of an intracardiac probe and transeptal catheter, respectively. Five million colour coded microspheres were injected into the left atrium via this catheter. After euthanasia the brain was used as proof of principle and the endpoint for determination of microcirculation at different time points. Homogeneous allocation of microspheres to different regions of the brain was found over time. Alternate slices from both hemispheres showed the following flow ranges: for slice 02; 0.57-1.02 mL/min/g, slice 04; 0.45-1.42 mL/min/g, slice 06; 0.35-1.87 mL/min/g, slice 08; 0.46-1.77 mL/min/g, slice 10; 0.34-1.28 mL/min/g. A mixed effect regression model demonstrated that the confidence interval did include zero suggesting that the apparent variability intra- and intersubject was not statistically significant, supporting the stability and reproducibility of the injection technique. This study demonstrates the feasibility of the transeptal injection of microspheres, showing a homogeneous distribution of blood flow through the brain unchanged over time and has established a new interventional model for the measurement of RMBF in ovine models. PMID:24102032

  10. Microsphere-Incorporated Hybrid Thermogel for Neuronal Differentiation of Tonsil Derived Mesenchymal Stem Cells.

    PubMed

    Patel, Madhumita; Moon, Hyo Jung; Jung, Bo Kyung; Jeong, Byeongmoon

    2015-07-15

    Neuronal differentiation of tonsil-derived mesenchymal stem cells (TMSCs) is investigated in a 3D hybrid system. The hybrid system is prepared by increasing the temperature of poly(ethylene glycol)-poly(l-alanine) aqueous solution to 37 °C through the heat-induced sol-to-gel transition, in which TMSCs and growth factor releasing microspheres are suspended. The in situ formed gel exhibits a modulus of 800 Pa at 37 °C, similar to that of brain tissue, and it is robust enough to hold the microspheres and cells during the 3D culture of TMSCs. The neuronal growth factors are released over 12-18 d, and the TMSCs in a spherical shape initially undergo multipolar elongation during the 3D culture. Significantly higher expressions of the neuronal biomarkers such as nuclear receptor related protein (Nurr-1), neuron specific enolase, microtubule associated protein-2, neurofilament-M, and glial fibrillary acidic protein are observed in both mRNA level and protein level in the hybrid systems than in the control experiments. This study proves the significance of a controlled drug delivery concept in tissue engineering or regenerative medicine, and a 3D hybrid system with controlled release of growth factors from microspheres in a thermogel can be a very promising tool. PMID:26033880

  11. Microsphere-Incorporated Hybrid Thermogel for Neuronal Differentiation of Tonsil Derived Mesenchymal Stem Cells.

    PubMed

    Patel, Madhumita; Moon, Hyo Jung; Jung, Bo Kyung; Jeong, Byeongmoon

    2015-07-15

    Neuronal differentiation of tonsil-derived mesenchymal stem cells (TMSCs) is investigated in a 3D hybrid system. The hybrid system is prepared by increasing the temperature of poly(ethylene glycol)-poly(l-alanine) aqueous solution to 37 °C through the heat-induced sol-to-gel transition, in which TMSCs and growth factor releasing microspheres are suspended. The in situ formed gel exhibits a modulus of 800 Pa at 37 °C, similar to that of brain tissue, and it is robust enough to hold the microspheres and cells during the 3D culture of TMSCs. The neuronal growth factors are released over 12-18 d, and the TMSCs in a spherical shape initially undergo multipolar elongation during the 3D culture. Significantly higher expressions of the neuronal biomarkers such as nuclear receptor related protein (Nurr-1), neuron specific enolase, microtubule associated protein-2, neurofilament-M, and glial fibrillary acidic protein are observed in both mRNA level and protein level in the hybrid systems than in the control experiments. This study proves the significance of a controlled drug delivery concept in tissue engineering or regenerative medicine, and a 3D hybrid system with controlled release of growth factors from microspheres in a thermogel can be a very promising tool.

  12. PEG-derivative effectively modifies the characteristics of indomethacin-PLGA microspheres destined to intra-articular administration.

    PubMed

    Puebla, Patricia; Pastoriza, Pilar; Barcia, Emilia; Fernández-Carballido, Ana

    2005-11-01

    The aim of this study was to obtain biodegradable indomethacin microspheres for intra-articular administration in rheumatoid arthritis, where angiogenic processes are involved. Indomethacin concentrations to achieve an anti-angiogenic effect would be five-times higher than an anti-inflammatory. Microspheres were prepared by solvent evaporation using PLGA. Indomethacin is a poor water-soluble drug with it being possible that dissolved and non-dissolved drug co-exist within the polymeric matrix resulting in rapid release. To control this release, an oil-PEG-derivative was incorporated, producing changes in morphology, crystallinity and indomethacin release. To minimize the amount of microspheres administered, a two-factor five-level central rotable composite 2(2)+star design was employed with two independent variables: indomethacin percentage and PEG-derivative percentage. The optimum formulation showed mean encapsulation efficiency of 94.3+/-2.2% and released 7.99+/-0.25 microg indomethacin/day/mg microspheres for 21 days. A dose of 20-50 mg of this formulation could be appropriate to achieve both anti-angiogenic and anti-inflammatory effects. Preliminary cytotoxicity studies performed in rat splenocytes showed an adequate cell viability.

  13. Fully automatic input function determination program for simple noninvasive (123)I-IMP microsphere cerebral blood flow quantification method.

    PubMed

    Yamashita, Kosuke; Uchiyama, Yoshikazu; Ofuji, Asato; Mimura, Hiroaki; Okumiya, Shintaro; Takaki, Akihiro; Sone, Teruki; Ito, Shigeki

    2016-09-01

    We recently developed a simple noninvasive (123)I-IMP microsphere (SIMS) method using chest dynamic planar images and brain single photon emission computed tomography. The SIMS method is an automatic analysis method, except for the process of setting the region of interest (ROI) of the input function. If a fully automatic ROI setting algorithm can be developed to determine the input function for the SIMS method, repeatability and reproducibility of the analysis of regional cerebral blood flow (rCBF) of the SIMS method can be guaranteed. The purpose of this study is to develop a fully automatic input function determination program for the SIMS method and to confirm the clinical usefulness of this program. The automatic input function determination program consists of two ROI setting programs for the PA and lung regions, and it is developed using the image phase analysis of a chest RI angiogram. To confirm the clinical usefulness of this program, the rCBF in 34 patients measured using the automatic method were compared with the values obtained through the manual setting method. Input functions by the automatic and manual methods were approximately equal. A good correlation was observed between the rCBF values obtained by the automatic method and those obtained by the manual setting method (r=0.96, p<0.01). Further, the total time taken for the automatic SIMS analysis is 1-2min as compared to 20-30min for the current analysis, and therefore, this technique contributes to the improvement of the throughput of nuclear medical examinations. PMID:27601249

  14. Polymeric microspheres

    DOEpatents

    Walt, David R.; Mandal, Tarun K.; Fleming, Michael S.

    2004-04-13

    The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

  15. Procion red MX-3B-derived poly(HEMA/EGDMA) microspheres for removal of cadmium ions

    SciTech Connect

    Denizli, A.; Bueyuektuncel, E.; Genc, O.; Piskin, E.

    1998-12-01

    The heavy metal pollution is becoming more and more serious an environmental problem throughout the world due to rapid industrialization. Heavy metals such as cadmium and mercury exhibit human toxicity at extremely low concentrations. Poly(hydroxyethyl methacrylate/ethylene glycol dimethacrylate) [poly(HEMA/EGDMA)]-Procion Red MX-3B microspheres were used for removal of Cd(II) ions from aqueous solutions containing different amounts of Cd(II) ions (5--60 ppm). Dye-derived microbeads carrying 8.95 {micro}mol Procion Red MX-3B/g polymer were used in the adsorption-desorption of Cd(II) ions. High adsorption rates were observed at the beginning of adsorption and then equilibrium was achieved in about 5--10 min. The maximum adsorption of Cd(II) ions onto the Procion Red MX-3B-derived microspheres (i.e., by chelate formation of Cd(II) ions with dye molecules) was about 4.2 mg Cd(II) ions/g polymer, which was observed at pH 7.0. While non-specific adsorption onto the underived microspheres was 0.93 mg Cd(II) ions/g polymer. More than 96% of the adsorbed Cd(II) ions was desorbed in 15 min by using 0.1 M HNO{sub 3} as an desorption agent. The regenerability of the dye-derived atmospheres was also sufficient.

  16. Comparison of CT-derived Ventilation Maps with Deposition Patterns of Inhaled Microspheres in Rats

    SciTech Connect

    Jacob, Rick E.; Lamm, W. J.; Einstein, Daniel R.; Krueger, Melissa; Glenny, Robb W.; Corley, Richard A.

    2015-04-01

    Purpose: Computer models for inhalation toxicology and drug-aerosol delivery studies rely on ventilation pattern inputs for predictions of particle deposition and vapor uptake. However, changes in lung mechanics due to disease can impact airflow dynamics and model results. It has been demonstrated that non-invasive, in vivo, 4DCT imaging (3D imaging at multiple time points in the breathing cycle) can be used to map heterogeneities in ventilation patterns under healthy and disease conditions. The purpose of this study was to validate ventilation patterns measured from CT imaging by exposing the same rats to an aerosol of fluorescent microspheres (FMS) and examining particle deposition patterns using cryomicrotome imaging. Materials and Methods: Six male Sprague-Dawley rats were intratracheally instilled with elastase to a single lobe to induce a heterogeneous disease. After four weeks, rats were imaged over the breathing cycle by CT then immediately exposed to an aerosol of ~1µm FMS for ~5 minutes. After the exposure, the lungs were excised and prepared for cryomicrotome imaging, where a 3D image of FMS deposition was acquired using serial sectioning. Cryomicrotome images were spatially registered to match the live CT images to facilitate direct quantitative comparisons of FMS signal intensity with the CT-based ventilation maps. Results: Comparisons of fractional ventilation in contiguous, non-overlapping, 3D regions between CT-based ventilation maps and FMS images showed strong correlations in fractional ventilation (r=0.888, p<0.0001). Conclusion: We conclude that ventilation maps derived from CT imaging are predictive of the 1µm aerosol deposition used in ventilation-perfusion heterogeneity inhalation studies.

  17. Comparison of CT-derived ventilation maps with deposition patterns of inhaled microspheres in rats

    PubMed Central

    Jacob, Richard E.; Lamm, Wayne J.; Einstein, Daniel R.; Krueger, Melissa A.; Glenny, Robb W.; Corley, Richard A.

    2016-01-01

    Purpose Computer models for inhalation toxicology and drug-aerosol delivery studies rely on ventilation pattern inputs for predictions of particle deposition and vapor uptake. However, changes in lung mechanics due to disease can impact airflow dynamics and model results. It has been demonstrated that non-invasive, in vivo, 4DCT imaging (3D imaging at multiple time points in the breathing cycle) can be used to map heterogeneities in ventilation patterns under healthy and disease conditions. The purpose of this study was to validate ventilation patterns measured from CT imaging by exposing the same rats to an aerosol of fluorescent microspheres (FMS) and examining particle deposition patterns using cryomicrotome imaging. Materials and Methods Six male Sprague-Dawley rats were intratracheally instilled with elastase to a single lobe to induce a heterogeneous disease. After four weeks, rats were imaged over the breathing cycle by CT then immediately exposed to an aerosol of ~1μm FMS for ~5 minutes. After the exposure, the lungs were excised and prepared for cryomicrotome imaging, where a 3D image of FMS deposition was acquired using serial sectioning. Cryomicrotome images were spatially registered to match the live CT images to facilitate direct quantitative comparisons of FMS signal intensity with the CT-based ventilation maps. Results Comparisons of fractional ventilation in contiguous, non-overlapping, 3D regions between CT-based ventilation maps and FMS images showed strong correlations in fractional ventilation (r=0.888, p<0.0001). Conclusion We conclude that ventilation maps derived from CT imaging are predictive of the 1μm aerosol deposition used in ventilation-perfusion heterogeneity inhalation studies. PMID:25513951

  18. Internal carotid occlusion: assessment, by Tc-99m-tagged microspheres, of bypass from superficial temporal to middle cerebral artery

    SciTech Connect

    Etani, H.; Kimura, K.; Iwata, Y.; Yoneda, S.; Imaizumi, M.; Nukada, T.

    1981-01-01

    The assessment of regional blood perfusion through the STA-MCA anastomosis was performed by the method of intracarotid injection of Tc-99m-labeled human albumin microspheres (HAM scintigraphy). This study included 11 anastomoses in 10 cases with occlusion of the internal carotid artery, who were treated by bypass surgery. The area of intracranial perfusion through the bypass was well defined in all cases by HAM scintigraphy. This method is excellent for imaging the regional blood perfusion through the anastomotic vessel, and the scintigraphic findings agree well with those of postoperative angiography. HAM scintigraphy will partially replace postoperative angiography because of its simplicity and low invasiveness.

  19. Internal carotid occlusion: assessment, by Tc-99m-tagged microspheres, of bypass from superficial temporal to middle cerebral artery

    SciTech Connect

    Etani, H.; Kimura, K.; Iwata, Y.

    1981-10-01

    The assessment of regional blood perfusion through the STA-MCA anastomosis was performed by the method of intracarotid injection of Tc-99m-labeled human albumin microspheres (HAM scintigraphy). This study included 11 anastomoses in 10 cases with occlusion of the internal carotid artery, who were treated by bypass surgery. The area of intracranial perfusion through the bypass was well defined in all cases by HAM scintigraphy. This method is excellent for imaging the regional blood perfusion through the anastomotic vessel, and the scintigraphic findings agree well with those of postoperative angiography. HAM scintigraphy will partially replace postoperative angiography because of its simplicity and low invasiveness.

  20. Effects of traumatic brain injury on regional cerebral blood flow in rats as measured with radiolabeled microspheres

    SciTech Connect

    Yamakami, I.; McIntosh, T.K.

    1989-02-01

    To clarify the effect of experimental brain injury on regional CBF (rCBF), repeated rCBF measurements were performed using radiolabeled microspheres in rats subjected to fluid-percussion traumatic brain injury. Three consecutive microsphere injections in six uninjured control rats substantiated that the procedure induces no significant changes in hemodynamic variables or rCBF. Animals were subjected to left parietal fluid-percussion brain injury of moderate severity (2.1-2.4 atm) and rCBF values were determined (a) prior to injury and 15 min and 1 h following injury (n = 7); and (b) prior to injury and 30 min and 2 h following injury (n = 7). At 15 min post injury, there was a profound reduction of rCBF in all brain regions studied (p less than 0.01). Although rCBF in the hindbrain had recovered to near-normal by 30 min post injury, rCBF in both injured and contralateral (uninjured) forebrain areas remained significantly suppressed up to 1 h post injury. At 2 h post injury, recovery of rCBF to near-normal values was observed in all brain regions except the focal area of injury (left parietal cortex) where rCBF remained significantly depressed (p less than 0.01). This prolonged focal oligemia at the injury site was associated with the development of reproducible cystic necrosis in the left parietotemporal cortex at 4 weeks post injury. Our results demonstrate that acute changes in rCBF occur following experimental traumatic brain injury in rats and that rCBF remains significantly depressed up to 2 h post injury in the area circumscribing the trauma site.

  1. Synthesis of lithium iron phosphate/carbon microspheres by using polyacrylic acid coated iron phosphate nanoparticles derived from iron(III) acrylate.

    PubMed

    Xu, Dongwei; He, Yan-Bing; Chu, Xiaodong; Ding, Zhaojun; Li, Baohua; He, Jianfu; Du, Hongda; Qin, Xianying; Kang, Feiyu

    2015-03-01

    Lithium iron phosphate/carbon (LiFePO4 /C) microspheres with high rate and cycling performance are synthesized from iron phosphate/polyacrylic acid (FePO4 /PAA) nanoparticles. Iron(III) acrylate is used as a precursor for both the iron and carbon sources. FePO4 nanoparticles are first produced by a coprecipitation reaction. The byproduct, acrylic acid ions, is polymerized in situ to form a uniform PAA layer on the surface of the FePO4 nanoparticles. The as-prepared LiFePO4 /C microspheres are composed of primary nanoparticles with sizes of 40-50 nm. The nanoparticles are fully coated with a thin, uniform carbon layer derived from the decomposition of the PAA layer. The uniform carbon-coating layer cooperates with interstitial and boundary carbon derived from sucrose successfully to construct an excellent interconnecting conductive network in the microspheres. As a result of the unique structure, the as-prepared LiFePO4 /C microspheres display both high electronic and ionic conductivities, which contribute to their high rate performance (162.9 mAh g(-1) at 0.1C and 126.1 mAh g(-1) at 5C) and excellent cycling stability (97.1% of capacity retention after 500 cycles at 5C/5C). PMID:25469674

  2. Synthesis of lithium iron phosphate/carbon microspheres by using polyacrylic acid coated iron phosphate nanoparticles derived from iron(III) acrylate.

    PubMed

    Xu, Dongwei; He, Yan-Bing; Chu, Xiaodong; Ding, Zhaojun; Li, Baohua; He, Jianfu; Du, Hongda; Qin, Xianying; Kang, Feiyu

    2015-03-01

    Lithium iron phosphate/carbon (LiFePO4 /C) microspheres with high rate and cycling performance are synthesized from iron phosphate/polyacrylic acid (FePO4 /PAA) nanoparticles. Iron(III) acrylate is used as a precursor for both the iron and carbon sources. FePO4 nanoparticles are first produced by a coprecipitation reaction. The byproduct, acrylic acid ions, is polymerized in situ to form a uniform PAA layer on the surface of the FePO4 nanoparticles. The as-prepared LiFePO4 /C microspheres are composed of primary nanoparticles with sizes of 40-50 nm. The nanoparticles are fully coated with a thin, uniform carbon layer derived from the decomposition of the PAA layer. The uniform carbon-coating layer cooperates with interstitial and boundary carbon derived from sucrose successfully to construct an excellent interconnecting conductive network in the microspheres. As a result of the unique structure, the as-prepared LiFePO4 /C microspheres display both high electronic and ionic conductivities, which contribute to their high rate performance (162.9 mAh g(-1) at 0.1C and 126.1 mAh g(-1) at 5C) and excellent cycling stability (97.1% of capacity retention after 500 cycles at 5C/5C).

  3. Conferring Natural-Derived Porous Microspheres with Surface Multifunctionality through Facile Coordination-Enabled Self-Assembly Process.

    PubMed

    Han, Pingping; Shi, Jiafu; Nie, Teng; Zhang, Shaohua; Wang, Xueyan; Yang, Pengfei; Wu, Hong; Jiang, Zhongyi

    2016-03-01

    In this study, multifunctional chitin microspheres are synthesized and utilized as a platform for multiple potential applications in enzyme immobilization, catalytic reduction and adsorption. Porous chitin microspheres with an average diameter of 111.5 μm and a porous architecture are fabricated through a thermally induced phase separation method. Then, the porous chitin microspheres are conferred with surface multifunctionality through facile coordination-enabled self-assembly of tannic acid (TA) and titanium (Ti(IV)) bis(ammonium lactate)dihydroxide (Ti-BALDH). The multipoint hydrogen bonds between TA and chitin microspheres confer the TA-Ti(IV) coating with high adhesion capability to adhere firmly to the surface of the chitin microspheres. In view of the biocompatibility, porosity and surface activity, the multifunctional chitin microspheres are used as carriers for enzyme immobilization. The enzyme-conjugated multifunctional porous microspheres exhibit high catalytic performance (102.8 U·mg(-1) yeast alcohol dehydrogenase). Besides, the multifunctional chitin microspheres also find potential applications in the catalytic reduction (e.g., reduction of silver ions to silver nanoparticles) and efficient adsorption of heavy metal ions (e.g., Pb(2+)) taking advantages of their porosity, reducing capability and chelation property.

  4. Unique insights into the intestinal absorption, transit, and subsequent biodistribution of polymer-derived microspheres

    PubMed Central

    Reineke, Joshua J.; Cho, Daniel Y.; Dingle, Yu-Ting; Morello, A. Peter; Jacob, Jules; Thanos, Christopher G.; Mathiowitz, Edith

    2013-01-01

    Polymeric microspheres (MSs) have received attention for their potential to improve the delivery of drugs with poor oral bioavailability. Although MSs can be absorbed into the absorptive epithelium of the small intestine, little is known about the physiologic mechanisms that are responsible for their cellular trafficking. In these experiments, nonbiodegradable polystyrene MSs (diameter range: 500 nm to 5 µm) were delivered locally to the jejunum or ileum or by oral administration to young male rats. Following administration, MSs were taken up rapidly (≤5 min) by the small intestine and were detected by transmission electron microscopy and confocal laser scanning microscopy. Gel permeation chromatography confirmed that polymer was present in all tissue samples, including the brain. These results confirm that MSs (diameter range: 500 nm to 5 µm) were absorbed by the small intestine and distributed throughout the rat. After delivering MSs to the jejunum or ileum, high concentrations of polystyrene were detected in the liver, kidneys, and lungs. The pharmacologic inhibitors chlorpromazine, phorbol 12-myristate 13-acetate, and cytochalasin D caused a reduction in the total number of MSs absorbed in the jejunum and ileum, demonstrating that nonphagocytic processes (including endocytosis) direct the uptake of MSs in the small intestine. These results challenge the convention that phagocytic cells such as the microfold cells solely facilitate MS absorption in the small intestine. PMID:23922388

  5. Unique insights into the intestinal absorption, transit, and subsequent biodistribution of polymer-derived microspheres.

    PubMed

    Reineke, Joshua J; Cho, Daniel Y; Dingle, Yu-Ting; Morello, A Peter; Jacob, Jules; Thanos, Christopher G; Mathiowitz, Edith

    2013-08-20

    Polymeric microspheres (MSs) have received attention for their potential to improve the delivery of drugs with poor oral bioavailability. Although MSs can be absorbed into the absorptive epithelium of the small intestine, little is known about the physiologic mechanisms that are responsible for their cellular trafficking. In these experiments, nonbiodegradable polystyrene MSs (diameter range: 500 nm to 5 µm) were delivered locally to the jejunum or ileum or by oral administration to young male rats. Following administration, MSs were taken up rapidly (≤ 5 min) by the small intestine and were detected by transmission electron microscopy and confocal laser scanning microscopy. Gel permeation chromatography confirmed that polymer was present in all tissue samples, including the brain. These results confirm that MSs (diameter range: 500 nm to 5 µm) were absorbed by the small intestine and distributed throughout the rat. After delivering MSs to the jejunum or ileum, high concentrations of polystyrene were detected in the liver, kidneys, and lungs. The pharmacologic inhibitors chlorpromazine, phorbol 12-myristate 13-acetate, and cytochalasin D caused a reduction in the total number of MSs absorbed in the jejunum and ileum, demonstrating that nonphagocytic processes (including endocytosis) direct the uptake of MSs in the small intestine. These results challenge the convention that phagocytic cells such as the microfold cells solely facilitate MS absorption in the small intestine. PMID:23922388

  6. Tissue engineered bulking agent with adipose-derived stem cells and silk fibroin microspheres for the treatment of intrinsic urethral sphincter deficiency.

    PubMed

    Shi, Li Bing; Cai, Hong Xia; Chen, Long Kun; Wu, Yan; Zhu, Shou An; Gong, Xiao Nan; Xia, Ya Xian; Ouyang, Hong Wei; Zou, Xiao Hui

    2014-02-01

    In this study we developed a tissue engineered bulking agent that consisted of adipose-derived stem cells (ADSCs) and silk fibroin microspheres to treat stress urinary incontinence caused by severe intrinsic sphincter deficiency (ISD). ISD models were established by completely transection of the bilateral pudendal nerve (PNT) and confirmed by the decreased leak-point pressure (LPP) and increased lumen area of urethra. Injection of silk fibroin microspheres could recover LPP and lumen area at 4 weeks but its efficacy disappears at 8, 12 weeks. Moreover, it was exciting to find that tissue engineered bulking agent brought long-term efficacy (at 4, 8, 12 weeks post-injection) on the recovery of LPP and lumen area. Concomitantly with the function, tissue engineered bulking agent treated group also improved the urethral sphincter structure as exhibited by better tissue regeneration. The findings showed that silk fibroin microspheres alone could work effectively in short-term, while tissue engineered bulking agent that combined silk fibroin microspheres with ADSCs exhibited promising long-term efficacy. This study developed a new strategy of tissue engineered bulking agent for future ISD therapy.

  7. Combination of chondroitinase ABC, glial cell line-derived neurotrophic factor and Nogo A antibody delayed-release microspheres promotes the functional recovery of spinal cord injury.

    PubMed

    Zhang, Yu; Gu, Zuchao; Qiu, Guixing; Song, Yueming

    2013-11-01

    Spinal cord injury (SCI) is one of the most devastating injuries for patients. Glial cell line-derived neurotrophic factor (GDNF) is an important neurotrophic factor for the regeneration of the spinal neuraxial bundle, but GDNF would degrade rapidly if the protein was injected into the site of injury; thus, it cannot exert its fullest effects. Therefore, we introduced a delivery system of GDNF, poly(lactide-co-glycolic acid) (PLGA) delayed-release microspheres, in the current study and observed the effect of PLGA-GDNF and the combination of PLGA-GDNF and another 2 agents PLGA-chondroitinase ABC (ChABC) and PLGA-Nogo A antibody in the treatment of SCI rats. Our results showed that PLGA-GDNF and the combination of chABC, GDNF, and Nogo A antibody microspheres could elevate the locomotor scores of SCI rats. The effect of PLGA-GDNF was much better than that of GDNF. The cortical somatosensory evoked potential was also improved by PLGA-GDNF and the combination of chABC, GDNF, and Nogo A antibody microspheres. Our results suggest that PLGA delayed-release microsphere may be a useful and effective tool in delivering protein agents into the injury sites of patients with SCI. This novel combination therapy may provide a new idea in promoting the functional recovery of the damaged spinal cord.

  8. Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods.

    PubMed

    Hu, Gaoshuang; Sheng, Wei; Zhang, Yan; Wang, Junping; Wu, Xuening; Wang, Shuo

    2016-05-18

    A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L(-1) in buffer and 0.5 μg kg(-1) in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24-25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods.

  9. Upconversion Nanoparticles and Monodispersed Magnetic Polystyrene Microsphere Based Fluorescence Immunoassay for the Detection of Sulfaquinoxaline in Animal-Derived Foods.

    PubMed

    Hu, Gaoshuang; Sheng, Wei; Zhang, Yan; Wang, Junping; Wu, Xuening; Wang, Shuo

    2016-05-18

    A novel fluorescence immunoassay for detecting sulfaquinoxaline (SQX) in animal-derived foods was developed using NaYF4:Yb/Tm upconversion nanoparticles (UCNPs) conjugated with antibodies as fluorescence signal probes, and monodisperse magnetic polystyrene microspheres (MMPMs) modified with coating antigen as immune-sensing capture probes for trapping and separating the signal probes. Based on a competitive immunoassay format, the detection limit of the proposed method for detecting SQX was 0.1 μg L(-1) in buffer and 0.5 μg kg(-1) in food samples. The recoveries of SQX in spiked samples ranged from 69.80 to 133.00%, with coefficients of variation of 0.24-25.06%. The extraction procedure was fast, simple, and environmentally friendly, requiring no organic solvents. In particular, milk samples can be analyzed directly after simple dilution. This method has appealing properties, such as sensitive fluorescence response, a simple and fast extraction procedure, and environmental friendliness, and could be applied to detecting SQX in animal-derived foods. PMID:27134048

  10. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow

    SciTech Connect

    Goodman, M.M.; Knapp, F.F. Jr.

    1990-02-13

    This patent describes radiopharmaceuticals useful in brain imaging. They comprise radiohalogenated thienylethylamine derivatives. The compounds are 5-halo-thiophene-2-isopropyl amines able to cross the blood-brain barrier and be retained for a sufficient length of time to allow the evaluation or regional blood flow by radioimaging of the brain.

  11. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow

    DOEpatents

    Goodman, Mark M.; Knapp, Jr., Furn F.

    1990-01-01

    Radiopharmaceuticals useful in brain imaging comprising radiohalogenated thienylethylamine derivatives. The compounds are 5-halo-thiophene-2-isopropyl amines able to cross the blood-brain barrier and be retained for a sufficient length of time to allow the evaluation or regional blood flow by radioimaging of the brain.

  12. In vitro and in vivo evaluation of mucoadhesive microspheres prepared for the gastrointestinal tract using polyglycerol esters of fatty acids and a poly(acrylic acid) derivative.

    PubMed

    Akiyama, Y; Nagahara, N; Kashihara, T; Hirai, S; Toguchi, H

    1995-03-01

    Two types of polyglycerol ester of fatty acid (PGEF)-based microspheres were prepared: Carbopol 934P (CP)-coated microspheres (CPC-microspheres) and CP-dispersion microspheres (CPD-microspheres). Comparative studies on mucoadhesion were done with these microspheres and PGEF-based microspheres without CP (PGEF-microspheres). In an in vitro adhesion test, the CPD-microspheres adhered strongly to mucosa prepared from rat stomach and small intestine because each CP particle in the CPD-microsphere was hydrated and swelled with part of it remaining within the microsphere and part extending to the surface serving to anchor the microsphere to the mucus layer. The gastrointestinal transit patterns after administration of the CPD-microspheres and PGEF-microspheres to fasted rats were fitted to a model in which the microspheres are emptied from the stomach monoexponentially with a lag time and then transit through the small intestine at zero-order. Parameters obtained by curve fitting confirmed that the gastrointestinal transit time of the CPD-microspheres was prolonged compared with that of the PGEF-microspheres. MRT in the gastrointestinal tract was also prolonged after administration of the CPD-microspheres compared with that following the administration of the PGEF-microspheres.

  13. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow

    SciTech Connect

    Goodman, M.M.; Knapp, F.F. Jr.

    1988-12-22

    An improved method of chemical synthesis of radiohalogenated thienylethylamine derivatives useful in brain imaging is described. These 5-halo-thiophene-2-isopropyl amines readily cross the blood- brain barrier and are retained in the brain for a sufficient length of time to allow evaluation of regional blood flow in the cerebrum. The advantages of the invention include a simpler synthesis route and a final compound which is less diluted with nonradioactive halogen. Use of this invention will allow clearer radioimaging or lower radiation doses to the patient, depending on the objective. 2 figs., 1 tab. (MHB)

  14. Hierarchical porous carbon microspheres derived from porous starch for use in high-rate electrochemical double-layer capacitors.

    PubMed

    Du, Si-Hong; Wang, Li-Qun; Fu, Xiao-Ting; Chen, Ming-Ming; Wang, Cheng-Yang

    2013-07-01

    Porous starch was used as a precursor for hierarchical porous carbon microspheres. The preparation consisted of stabilisation, carbonisation and KOH activation, and the resultant hierarchical porous carbon microspheres had a large BET surface area of 3251 m(2)g(-1). Due to the large surface area and the hierarchical pore structure, electrodes made of the hierarchical porous carbon microsphere materials had high specific capacitances of 304 Fg(-1) at a current density of 0.05 Ag(-1) and 197 Fg(-1) at a current density of 180 Ag(-1) when used in a symmetric capacitor with 6M KOH as the electrolyte. After 10,000 cycles, the capacitor still exhibited a stable performance with a capacitance retention of 98%. These results indicate that porous starch is an excellent precursor to prepare high performance electrode materials for EDLCs.

  15. Trading polymeric microspheres: exchanging DNA molecules via microsphere interaction.

    PubMed

    Morimoto, Nobuyuki; Muramatsu, Kanna; Nomura, Shin-ichiro M; Suzuki, Makoto

    2015-04-01

    A new class of artificial molecular transport system is constructed by polymeric microspheres. The microspheres are prepared by self-assembly of poly(ethylene glycol)-block-poly(3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate), PEG-b-PDMAPS, by intermolecular dipole-dipole interaction of sulfobetaine side chains in water. Below the upper critical solution temperature (UCST) of PEG-b-PDMAPS, the microspheres (∼1μm) interact with other microspheres by partial and transit fusion. In order to apply the interaction between microspheres, a 3'-TAMRA-labeled single-stranded DNA oligomer (ssDNA) is encapsulated into a PEG-b-PDMAPS microsphere by thermal treatment. The exchange of ssDNA between microspheres is confirmed by fluorescence resonance energy transfer (FRET) quenching derived from double-stranded formation with complementary 5'-BHQ-2-labeled ssDNA encapsulated in PEG-b-PDMAPS microspheres. The exchange rate of ssDNA is controllable by tuning the composition of the polymer. The contact-dependent transport of molecules can be applied in the areas of microreactors, sensor devices, etc. PMID:25731098

  16. Trading polymeric microspheres: exchanging DNA molecules via microsphere interaction.

    PubMed

    Morimoto, Nobuyuki; Muramatsu, Kanna; Nomura, Shin-ichiro M; Suzuki, Makoto

    2015-04-01

    A new class of artificial molecular transport system is constructed by polymeric microspheres. The microspheres are prepared by self-assembly of poly(ethylene glycol)-block-poly(3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate), PEG-b-PDMAPS, by intermolecular dipole-dipole interaction of sulfobetaine side chains in water. Below the upper critical solution temperature (UCST) of PEG-b-PDMAPS, the microspheres (∼1μm) interact with other microspheres by partial and transit fusion. In order to apply the interaction between microspheres, a 3'-TAMRA-labeled single-stranded DNA oligomer (ssDNA) is encapsulated into a PEG-b-PDMAPS microsphere by thermal treatment. The exchange of ssDNA between microspheres is confirmed by fluorescence resonance energy transfer (FRET) quenching derived from double-stranded formation with complementary 5'-BHQ-2-labeled ssDNA encapsulated in PEG-b-PDMAPS microspheres. The exchange rate of ssDNA is controllable by tuning the composition of the polymer. The contact-dependent transport of molecules can be applied in the areas of microreactors, sensor devices, etc.

  17. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1987-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  18. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1986-01-01

    Microspheres of acrolein homopolymers and copolymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  19. Polyacrolein microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1983-01-01

    Microspheres of acrolein homopolymers and co-polymer with hydrophillic comonomers such as methacrylic acid and/or hydroxyethylmethacrylate are prepared by cobalt gamma irradiation of dilute aqueous solutions of the monomers in presence of suspending agents, especially alkyl sulfates such as sodium dodecyl sulfate. Amine or hydroxyl modification is achieved by forming adducts with diamines or alkanol amines. Carboxyl modification is effected by oxidation with peroxides. Pharmaceuticals or other aldehyde reactive materials can be coupled to the microspheres. The microspheres directly form antibody adducts without agglomeration.

  20. Subcutaneous Construction of Engineered Adipose Tissue with Fat Lobule-Like Structure Using Injectable Poly-Benzyl-L-Glutamate Microspheres Loaded with Adipose-Derived Stem Cells.

    PubMed

    Sun, Wentao; Fang, Jianjun; Yong, Qi; Li, Sufang; Xie, Qingping; Yin, Jingbo; Cui, Lei

    2015-01-01

    Porous microcarriers were fabricated from synthesized poly(γ-benzyl-L-glutamate) (PBLG) polymer to engineer adipose tissue with lobule-like structure via the injectable approach. The adipogenic differentiation of human adipose-derived stem cells (hASCs) seeded on porous PBLG microcarriers was determined by adipogenic gene expression and glycerol-3-phosphate dehydrogenase enzyme activity. In vitro adipogenic cultivation was performed for 7 days, and induced hASC/PBLG complex (Adi-ASC/PBLG group) was subcutaneously injected into nude mice. Injections of PBLG microcarriers alone (PBLG group) and non-induced hASC/PBLG complex (ASC/PBLG group) served as controls. Newly formed tissues were harvested after 4 and 8 weeks. Generation of subcutaneous adipose tissue with typical lobule-like structure separated by fibrous septa was observed upon injection of adipogenic-induced hASC/microsphere complex. Adipogenesis significantly increased in the Adi-ASC/PBLG group compared with the control groups. The angiogenesis in the engineered adipose tissue was comparable to that in normal tissue as determined by capillary density and luminal diameter. Cell tracking assay demonstrated that labeled hASCs remained detectable in the neo-generated tissues 8 weeks post-injection using green fluorescence protein-labeled hASCs. These results indicate that adipose tissue with typical lobule-like structure could be engineered using injectable porous PBLG microspheres loaded with adipogenic-induced hASCs.

  1. Potentiated endothelium-derived hyperpolarizing factor-mediated dilations in cerebral arteries following mild head injury.

    PubMed

    Golding, E M; You, J; Robertson, C S; Bryan, R M

    2001-07-01

    Evidence in the literature suggests that endothelium-derived hyperpolarizing factor (EDHF) may act in a compensatory manner such that during conditions of compromised nitric oxide (NO), EDHF serves as a back-up mechanism. Given that constitutive NO synthase is chronically downregulated after head trauma, we tested the hypothesis that EDHF is potentiated following injury. Male adult rats were subjected to either sham injury (n = 27) or mild controlled cortical impact (CCI) injury (n = 26). Branches of the middle cerebral artery (MCA) directly within the contusion site were harvested either 1 or 24 h later, pressurized to 60 mm Hg in a vessel chamber and allowed to develop spontaneous tone. Relaxation to luminal application of adenosine triphosphate (ATP) was similar in all groups. Relaxation to ATP in the presence of L-NAME (N(G)-nitro-L-arginine methyl ester) and indomethacin was similar in all groups except for vessels isolated at 24 h following mild CCI injury. In this case, L-NAME and indomethacin had no effect on the ATP-mediated dilation. The ATP-mediated dilation in L-NAME and indomethacin-treated MCA branches was inhibited by charybdotoxin, an inhibitor of large conductance Ca2+-sensitive K+ channels. These findings suggest that there is a significant potentiation of the EDHF-mediated dilation to ATP in cerebral arteries isolated at 24 h following mild CCI injury.

  2. Intraventricular brain-derived neurotrophic factor reduces infarct size after focal cerebral ischemia in rats.

    PubMed

    Schäbitz, W R; Schwab, S; Spranger, M; Hacke, W

    1997-05-01

    Brain-derived neurotrophic factor (BDNF), acting through the high-affinity receptor tyrosine kinase (TrkB), is widely distributed throughout the central nervous system and displays in vitro trophic effects on a wide range of neuronal cells, including hippocampal, cerebellar, and cortical neurons. In vivo, BDNF rescues motorneurons, hippocampal, and substantia nigral dopaminergic cells from traumatic and toxic brain injury. After transient middle cerebral artery occlusion (MCAO), upregulation of BDNF-mRNA in cortical neurons suggests that BDNF potentially plays a neuroprotective role in focal cerebral ischemia. In the current study, BDNF (2.1 micrograms/d) in vehicle or vehicle alone (controls) was delivered intraventricularly for 8 days, beginning 24 hours before permanent middle cerebral artery occlusion by intraluminal suture in Wistar rats (n = 13 per group). There were no differences in physiological variables recorded during surgery for the two groups. Neurological deficit (0 to 4 scale), which was assessed on a daily basis, improved in BDNF-treated animals compared with controls (P < 0.05; analysis of variance and Scheffe's test). There were no significant differences in weight in BDNF-treated animals and controls during the experiment. After elective killing on day 7 after MCAO, brains underwent 2,3,5-triphenyltetrazolium chloride staining for calculation of the infarct volume and for histology (hematoxylin and eosin and glial fibrillary acid protein). The mean total infarct volume was 83.1 +/- 27.1 mm3 in BDNF-treated animals and 139.2 +/- 56.4 mm3 in controls (mean +/- SD; P < 0.01, unpaired, two-tailed t-test). The cortical infarct volume was 10.8 +/- 7.1 mm3 in BDNF-treated animals and 37.9 +/- 19.8 mm3 in controls (mean +/- SD; P < 0.05; unpaired, two-tailed t-test), whereas ischemic lesion volume in caudoputaminal infarction was not significantly different. These results show that pretreatment with intraventricular BDNF reduces infarct size after focal

  3. Brain-Derived Neurotrophic Factor Stimulates Production of Prostacyclin in Cerebral Arteries

    PubMed Central

    Santhanam, Anantha Vijay R.; Smith, Leslie A.; Katusic, Zvonimir S.

    2009-01-01

    Background The role of Brain Derived Neurotrophic Factor (BDNF) and its receptor, tropomyosin receptor kinase B (TrkB), in control of cerebral circulation is poorly understood. The present study was designed to investigate the cerebral vascular effects of BDNF in vivo. Methods Replication incompetent adenovirus encoding either rat BDNF (AdBDNF) or green fluorescent protein (AdGFP) was injected intracisternally into rabbits. Forty eight hours later, animals were euthanized. Plasma and cerebrospinal fluid (CSF) levels of BDNF were measured by ELISA, vasomotor function of isolated basilar arteries was studied in organ chambers, protein expression in the basilar arteries was studied by Western blotting, prostanoid levels measured by ELISA and cyclic adenosine 3′,5′-monophosphate (cyclic AMP) levels were measured by radioimmunoassay. Results The levels of BDNF in the CSF were significantly elevated in AdBDNF-treated rabbits as compared to AdGFP-treated rabbits (37 ± 5 ng/ml vs. 0.006 ± 0.003 ng/ml, respectively, P<0.05, n=14). Western blotting studies revealed that in basilar arteries AdBDNF increased protein expression of prostacyclin (PGI2) synthase, while expression of endothelial nitric oxide synthase (eNOS) and phosphorylated (Ser 1177) eNOS remained unchanged. During incubation with arachidonic acid (1 μmol/L), PGI2 production and levels of cyclic AMP were significantly elevated only in AdBDNF-treated rabbit basilar arteries (P<0.05, n=6). Relaxations to acetylcholine (10−9 to 10−5 mol/L) and arachidonic acid (10−9 to 10−5 mol/L) were significantly potentiated in basilar arteries from rabbits injected with AdBDNF. Potentiation of relaxations to acetylcholine in AdBDNF-treated basilar arteries was inhibited by the non-selective cyclooxygenase inhibitor, indomethacin (10−5 mol/l, P<0.05, n=6) and constitutive phospholipase A2 inhibitor, AACOCF3 (2 × 10−5 mol/L, P<0.05, n=5). Conclusion Our results demonstrate that in cerebral arteries, BDNF

  4. Porous nitrogen-doped carbon microspheres derived from microporous polymeric organic frameworks for high performance electric double-layer capacitors.

    PubMed

    Han, Jinpeng; Xu, Guiyin; Dou, Hui; MacFarlane, Douglas R

    2015-02-01

    This research presents a simple and efficient method to synthesize porous nitrogen-doped carbon microspheres (PNCM) by the carbonization of microporous poly(terephthalaldehyde-pyrrole) organic frameworks (PtpOF). The common KOH activation process is used to tune the porous texture of the PNCM and produce an activated-PNCM (A-PNCM). The PNCM and A-PNCM with specific surface area of 921 and 1303 m(2)  g(-1) , respectively, are demonstrated as promising candidates for EDLCs. At a current density of 0.5 A g(-1) , the specific capacitances of the PNCM and A-PNCM are 248 and 282 F g(-1) , respectively. At the relatively high current density of 20 A g(-1) , the capacitance remaining is 95 and 154 F g(-1) , respectively. Capacity retention of the A-PNCM is more than 92% after 10000 charge/discharge cycles at a current density of 2 A g(-1) .

  5. Glass microspheres

    SciTech Connect

    Day, D.E.; Ehrhardt, G.J.

    1988-12-06

    This patent describes a glass microsphere having a diameter of about 54 micrometers or less and adapted for radiation therapy of a mammal. The glass consists of essentially an yttrium oxide-aluminosilicate glass composition lying substantially within a quadrilateral region of the ternary composition diagram of the yttria-alumina-silica system, the quadrilateral region being defined by its four corners having the following combination of weight proportions of the components: 20% silica, 10% alumina, 70% yttria; 70% silica, 10% alumina, 20% yttria; 70% silica, 20% alumina, 10% yttria; and 20% silica, 45% alumina, 35% yttria, the glass having a chemical durability such that subsequent to irradiation and administration of the microsphere to the mammal, the mircosphere will not release a significant amount of yttrium-90 into the mammal's system.

  6. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, R.M.

    A method and apparatus is disclosed for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  7. Microradiographic microsphere manipulator

    DOEpatents

    Singleton, Russell M.

    1980-01-01

    A method and apparatus for radiographic characterization of small hollow spherical members (microspheres), constructed of either optically transparent or opaque materials. The apparatus involves a microsphere manipulator which holds a batch of microspheres between two parallel thin plastic films for contact microradiographic characterization or projection microradiography thereof. One plastic film is translated to relative to and parallel to the other to roll the microspheres through any desired angle to allow different views of the microspheres.

  8. Pharmacological Effects of Erythropoietin and its Derivative Carbamyl erythropoietin in Cerebral White Matter Injury

    NASA Astrophysics Data System (ADS)

    Liu, Wei

    Periventricular leukomalacia (PVL) is the predominant form of brain injury in the premature infant and the most common cause of cerebral palsy, yet no therapy currently exists for this serious human disorder. As PVL often occurs in preterm infants suffering from cerebral hypoxia/ischemia with or without prior exposure to maternal-fetal infection/inflammation, we used hypoxia/ischemia with or without lipopolysaccharide (LPS) injection, to produce clinically relevant PVL-like lesions in the white matter in postnatal day six (P6) mice. We studied the white matter pathology under different conditions, such as different durations of hypoxia and different doses of LPS, to evaluate the effects of those etiological factors on neonatal white matter injury. Distinct related pathological events were investigated at different time points during the progression of PVL. We used immunohistochemistry, histological analysis, and electron microscopy (EM) to study demylination that occurs in the white matter area, which is consistent with the pathology of human PVL. Previous studies have shown that erythropoietin (EPO) and its derivative carbamylated EPO (CEPO) are neuroprotective in various experimental models of brain injury. However, none of these studies investigated their efficacy against white matter injury using appropriate animal models of PVL. We produced unilateral or bilateral white matter injury in P6 mice using unilateral carotid ligation (UCL) followed by hypoxia (6% oxygen, 35 min) or by UCL/hypoxia plus LPS injection, respectively. We administered a single intraperitoneal (i.p.) dose of EPO or CEPO (5000 IU/kg) immediately after the insult, and found both drugs to provide significant protection against white matter injury in PVL mice compared to vehicle-treated groups. In addition, EPO and CEPO treatments attenuated neurobehavioral dysfunctions in an acute manner after PVL injury. EPO and CEPO have relatively few adverse effects, and thus may be a therapeutic agent

  9. Hybrid microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1985-01-01

    Substrates, particularly inert synthetic organic resin beads (10) or sheet (12) such as polystyrene are coated with a covalently bound layer (24) of polyacrolein by irradiation a solution (14) of acrolein or other aldehyde with high intensity radiation. Individual microspheres (22) are formed which attach to the surface to form the aldehyde containing layer (24). The aldehyde groups can be converted to other functional groups by reaction with materials such as hydroxylamine. Adducts of proteins such as antibodies or enzymes can be formed by direct reaction with the surface aldehyde groups.

  10. Co-delivery of adipose-derived stem cells and growth factor-loaded microspheres in RGD-grafted N-methacrylate glycol chitosan gels for focal chondral repair.

    PubMed

    Sukarto, Abby; Yu, Claire; Flynn, Lauren E; Amsden, Brian G

    2012-08-13

    The coencapsulation of growth factor-loaded microspheres with adipose-derived stem cells (ASCs) within a hydrogel matrix was studied as a potential means to enhance ASC chondrogenesis in the development of a cell-based therapeutic strategy for the regeneration of partial thickness chondral defects. A photopolymerizable N-methacrylate glycol chitosan (MGC) was employed to form an in situ gel used to encapsulate microspheres loaded with bone morphogenetic protein 6 (BMP-6) and transforming growth factor-β3 (TGF-β3) with human ASCs. ASC viability and retention were enhanced when the Young's modulus of the MGC ranged between 225 and 380 kPa. Grafting an RGD-containing peptide onto the MGC backbone (RGD-MGC) improved ASC viability within the gels, remaining at greater than 90% over 14 days in culture. The effects of BMP-6 and TGF-β3 released from the polymer microspheres on ASC chondrogenesis were assessed, and the level of differentiation was compared to ASCs in control gels containing nongrowth factor-loaded microspheres cultured with and without the growth factors supplied in the medium. There was enhanced expression of chondrogenic markers at earlier time points when the ASCs were induced with the sustained and local release of BMP-6 and TGF-β3 from the microspheres. More specifically, the normalized glycosaminoglycan and collagen type II protein expression levels were significantly higher than in the controls. In addition, the ratio of collagen type II to type I was significantly higher in the microsphere delivery group and increased over time. End-point RT-PCR analysis supported that there was a more rapid induction and enhancement of ASC chondrogenesis in the controlled release group. Interestingly, in all of the assays, there was evidence of chondrogenic differentiation when the ASCs were cultured in the gels in the absence of growth factor stimulation. Overall, the co-delivery of growth-factor-loaded microspheres and ASCs in RGD-modified MGC gels

  11. [Studying the neuroprotective effect of the novel glutamic acid derivative neiroglutam on focal cerebral ischemia in rats].

    PubMed

    Tiurenkov, I N; Kurkin, D V; Bakulin, D A; Volotova, E V

    2014-01-01

    We have studied the neuroprotective effect of the novel glutamic acid derivative neiroglutam on reversible focal cerebral ischemia in rats. The neuroprotective drug action was assessed by the ability to reduce the severity of neurological deficit (1, 2, 3, 5 and 7 days), forelimb fine-motor disorders (in the ladder test), hind limb motor activity (beam-walking test), and volume of the infarct zone upon 7-day pathologic exposure. It was found that the therapeutic administration of neiroglutam (26 mg/kg, i.p., for 7 days) reduces the volume of necrosis of cerebral tissues in case of focal brain ischemia in animals (on the average by 38%, (p < 0.05) and decreases the severity of motor disorders, which indicates the presence of neuroprotective effect of this compound. PMID:25365863

  12. A derivative of the CRMP2 binding compound lanthionine ketimine provides neuroprotection in a mouse model of cerebral ischemia.

    PubMed

    Nada, Shadia E; Tulsulkar, Jatin; Raghavan, Aparna; Hensley, Kenneth; Shah, Zahoor A

    2012-12-01

    Lanthionines are novel neurotrophic and neuroprotective small molecules that show promise for the treatment of neurodegenerative diseases. In particular, a recently developed, cell permeable lanthionine derivative known as LKE (lanthionine ketimine 5-ethyl ester) promotes neurite growth at low nanomolar concentrations. LKE also has neuroprotective, anti-apoptotic, and anti-inflammatory properties. Its therapeutic potential in cerebral ischemia and its mechanisms of neurotrophic action remain to be fully elucidated. Here, we hypothesize that the neuroprotective actions of LKE could result from induction or modulation of CRMP2. We found that treating primary cultured mouse neurons with LKE provided significant protection against t-butyl hydroperoxide-induced neuronal death possibly through CRMP2 upregulation. Similarly, in vivo studies showed that LKE pre and/or post-treatment protects mice against permanent distal middle cerebral artery occlusion (p-MCAO) as evidenced by lower stroke lesions and improved functional outcomes in terms of rotarod, grip strength and neurologic deficit scores in treated groups. Protein expression levels of CRMP2 were higher in brain cortices of LKE pretreated mice, suggesting that LKE's neuroprotective activity may be CRMP2 dependent. Lower activity of cleaved PARP-1 and higher activity of SIRT-1 was also observed in LKE treated group suggesting its anti-apoptotic properties. Our results suggest that LKE has potential as a therapeutic intervention in cerebral ischemia and that part of its protective mechanism may be attributed to CRMP2 mediated action and PARP-1/SIRT-1 modulation. PMID:23036362

  13. A derivative of the CRMP2 binding compound lanthionine ketimine provides neuroprotection in a mouse model of cerebral ischemia.

    PubMed

    Nada, Shadia E; Tulsulkar, Jatin; Raghavan, Aparna; Hensley, Kenneth; Shah, Zahoor A

    2012-12-01

    Lanthionines are novel neurotrophic and neuroprotective small molecules that show promise for the treatment of neurodegenerative diseases. In particular, a recently developed, cell permeable lanthionine derivative known as LKE (lanthionine ketimine 5-ethyl ester) promotes neurite growth at low nanomolar concentrations. LKE also has neuroprotective, anti-apoptotic, and anti-inflammatory properties. Its therapeutic potential in cerebral ischemia and its mechanisms of neurotrophic action remain to be fully elucidated. Here, we hypothesize that the neuroprotective actions of LKE could result from induction or modulation of CRMP2. We found that treating primary cultured mouse neurons with LKE provided significant protection against t-butyl hydroperoxide-induced neuronal death possibly through CRMP2 upregulation. Similarly, in vivo studies showed that LKE pre and/or post-treatment protects mice against permanent distal middle cerebral artery occlusion (p-MCAO) as evidenced by lower stroke lesions and improved functional outcomes in terms of rotarod, grip strength and neurologic deficit scores in treated groups. Protein expression levels of CRMP2 were higher in brain cortices of LKE pretreated mice, suggesting that LKE's neuroprotective activity may be CRMP2 dependent. Lower activity of cleaved PARP-1 and higher activity of SIRT-1 was also observed in LKE treated group suggesting its anti-apoptotic properties. Our results suggest that LKE has potential as a therapeutic intervention in cerebral ischemia and that part of its protective mechanism may be attributed to CRMP2 mediated action and PARP-1/SIRT-1 modulation.

  14. Skin-derived precursor cells promote angiogenesis and stimulate proliferation of endogenous neural stem cells after cerebral infarction.

    PubMed

    Mao, Duo; Yao, Xinpeng; Feng, Guowei; Yang, Xiaoqing; Mao, Lina; Wang, Xiaomin; Ke, Tingyu; Che, Yongzhe; Kong, Deling

    2015-01-01

    Stroke is one of the most common diseases that caused high mortality and has become burden to the health care systems. Stem cell transplantation has shown therapeutic effect in ameliorating ischemic damage after cerebral artery occlusion mainly due to their neurogenesis, immune regulation, or effects on the plasticity, proliferation, and survival of host cells. Recent studies demonstrated that skin-derived precursor cells (SKPs) could promote central nervous system regeneration in spinal cord injury model or the neonatal peripheral neuron. Here, we investigated the therapeutic potential of SKPs in a rat model of cerebral ischemia. SKPs were isolated, expanded, and transplanted into rat cortex and striatum after transient middle cerebral artery occlusion. Our results revealed that SKPs transplantation could improve the behavioral measures of neurological deficit. Moreover, immunohistology confirmed that SKPs could secrete basic FGF and VEGF in the ischemic region and further markedly increase the proliferation of endogenous nestin(+) and βIII-tubulin(+) neural stem cells. Furthermore, increased angiogenesis induced by SKPs was observed by vWF and α-SMA staining. These data suggest that SKPs induced endogenous neurogenesis and angiogenesis and protected neuron from hypoxic-ischemic environment. In conclusion, SKPs transplantation may be a promising approach in treatment of stroke.

  15. microsphere assemblies

    NASA Astrophysics Data System (ADS)

    Peña-Flores, Jesús I.; Palomec-Garfias, Abraham F.; Márquez-Beltrán, César; Sánchez-Mora, Enrique; Gómez-Barojas, Estela; Pérez-Rodríguez, Felipe

    2014-09-01

    The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe+3 ion concentration increases.

  16. NO-Donor Dihydroartemisinin Derivatives as Multitarget Agents for the Treatment of Cerebral Malaria.

    PubMed

    Bertinaria, Massimo; Orjuela-Sanchez, Pamela; Marini, Elisabetta; Guglielmo, Stefano; Hofer, Anthony; Martins, Yuri C; Zanini, Graziela M; Frangos, John A; Gasco, Alberto; Fruttero, Roberta; Carvalho, Leonardo J M

    2015-10-01

    Hybrid products in which the dihydroartemisinin scaffold is combined with NO-donor furoxan and NONOate moieties have been synthesized and studied as potential tools for the treatment of cerebral malaria (CM). The designed products were able to dilate rat aorta strips precontracted with phenylephrine with a NO-dependent mechanism. All hybrid compounds showed preserved antiplasmodial activity in vitro and in vivo against Plasmodium berghei ANKA, comparable to artesunate and artemether. Hybrid 10, selected for additional studies, was capable of increasing survival of mice with late-stage CM from 27.5% to 51.6% compared with artemether. Artemisinin-NO-donor hybrid compounds show promise as potential new drugs for treating cerebral malaria. PMID:26367273

  17. Cyclooxygenase-derived vasoconstriction restrains hypoxia-mediated cerebral vasodilation in young adults with metabolic syndrome

    PubMed Central

    Harrell, John W.

    2013-01-01

    Poor cerebrovascular function in metabolic syndrome (MetSyn) likely contributes to elevated risk of cerebrovascular disease in this growing clinical population. Younger MetSyn adults without clinical evidence of cerebrovascular disease exhibit preserved hypercapnic vasodilation yet markedly impaired hypoxic vasodilation, but the mechanisms behind reduced hypoxic vasodilation are unknown. Based on data from rats, we tested the hypothesis that younger adults with MetSyn exhibit reduced cerebral hypoxic vasodilation due to loss of vasodilating prostaglandins. Middle cerebral artery velocity (MCAv) was measured with transcranial Doppler ultrasound in adults with MetSyn (n = 13, 33 ± 3 yr) and healthy controls (n = 15, 31 ± 2 yr). Isocapnic hypoxia was induced by titrating inspired oxygen to lower arterial saturation to 90% and 80% for 5 min each. Separately, hypercapnia was induced by increasing end-tidal CO2 10 mmHg above baseline levels. Cyclooxygenase inhibition (100 mg indomethacin) was conducted in a randomized double-blind, placebo controlled design. MCAv was normalized for group differences in blood pressure (healthy: 89 ± 2 mmHg vs. MetSyn: 102 ± 2 mmHg) as cerebrovascular conductance index (CVCi), and used to assess cerebral vasodilation. Hypoxia increased CVCi in both groups; however, vasodilation was ∼55% lower in MetSyn at SpO2 = 80% (P < 0.05). Indomethacin tended to decrease hypoxic vasodilation in healthy controls, and unexpectedly increased dilation in MetSyn (P < 0.05). In contrast to hypoxia, hypercapnia-mediated vasodilation was similar between groups, as was the decrease in vasodilation with indomethacin. These data indicate increased production of vasoconstrictor prostaglandins restrains hypoxic cerebral vasodilation in MetSyn, preventing them from responding appropriately to this important physiological stressor. PMID:24213610

  18. Derivative spectrophotometric analysis of cerebrospinal fluid for the detection of a ruptured cerebral aneurysm

    NASA Astrophysics Data System (ADS)

    Bhadri, P. R.; Majumder, A.; Morgan, C. J.; Pyne, G. J.; Zuccarello, M.; Jauch, E.; Wagner, K. R.; Clark, J. F.; Caffery, J., Jr.; Beyette, Fred R., Jr.

    2003-11-01

    A cerebral aneurysm is a weakened portion of an artery in the brain. When a cerebral aneurysm ruptures, a specific type of bleeding known as a subarachnoid hemorrhage (SAH) occurs. No test exists currently to screen people for the presence of an aneurysm. The diagnosis of a SAH is made after an aneurysm ruptures, and the literature indicates that nearly one-third of patients with a SAH are initially misdiagnosed and subjected to the risks associated with aneurysm re-rupture. For those individuals with a suspected SAH, a computerized tomography (CT) scan of the brain usually demonstrates evidence of the bleeding. However, in a considerable portion of people, the CT scan is unable to detect the blood that has escaped from the blood vessel. For circumstances when a SAH is suspected despite a normal CT scan, physicians make the diagnosis of SAH by performing a spinal tap. A spinal tap uses a needle to sample the cerebrospinal fluid (CSF) collected from the patient"s back; CSF is tainted with blood after the aneurysm ruptures. To distinguish between a common headache and a SAH, a fast and an effective solution is required. We describe the development of an effective detection system integrating hardware and a powerful software interface solution. Briefly, CSF from the patient is aspirated and excited with an appropriate wavelength of light. The software employs spectrophotometric analysis of the output spectra and lays the foundation for the development of portable and user-friendly equipment for detection of a ruptured cerebral aneurysm.

  19. Economic Evaluation for the Production of Sorbents and Catalysts Derived from Hydrous Titanium Oxide Microspheres Prepared by the HMTA Internal Gelation Process

    SciTech Connect

    Collins, J.L.

    2001-01-11

    Hydrous metal oxides of Zr, Ti, Hf, Fe, Al, etc. are inorganic ion exchangers that have high selectivities and efficiencies for separating and removing fission products, actinides, and other undesirable elements from aqueous waste streams. In most cases, these ion exchangers are commercially available only as fine powders or as unstable granular particles that are not readily adaptable to continuous processing techniques such as column chromatography. Hydrous metal oxides can be prepared as microspheres by the internal gelation process. This process is unique in that it provides a means of making a usable engineered form of inorganic ion exchanger that can be used in large-scale column separations. With such material, the flow dynamics in column operations would be greatly enhanced. In addition, the microspheres are in a stable form that has little or no tendency to degrade under dynamic conditions. Another advantage of the process is that the gelation time and size of the microspheres can be controlled. Also, microspheres can be reproducibly prepared on either a small or a large scale-which is not always true for batch preparation of the powdered or granular forms. The use of these materials can be expanded in a number of ways. The process allows for the microspheres to be homogeneously embedded with fine particles of other selective ion exchangers, and for the microspheres (undried) to be chemically converted to microspheres of other ion-exchanger materials such as phosphates, silicophosphates, hexacyanoferrates, tungstates, and molybdates. This report presents an economic evaluation of the preparation of hydrous titanium oxide (HTiO) microspheres by an internal gelation process for use in making ion exchangers, catalysts, and getters. It also examines the estimated costs for a company to produce the material but does not discuss the price to be charged since that value would take into account company policy-matters that cannot be covered here. Since the volume

  20. Bone marrow derived mesenchymal stem cells alleviated brain injury via down-regulation of interleukin-1β in focal cerebral ischemic rats

    PubMed Central

    Zhao, Yansong; Wang, Xiaoli; Dong, Peng; Xu, Qinyan; Ma, Ze; Mu, Qingjie; Sun, Xihe; Jiang, Zhengchen; Wang, Xin

    2016-01-01

    Interleukin-1β (IL-1β) plays an important role in brain injury after focal ischemia, and bone marrow-derived mesenchymal stem cells (BMSCs) are capable of reducing the expression of IL-1β, we investigated the effects of BMSCs transplantation on brain edema and cerebral infarction as well as the underlying mechanisms via IL-1β. Male Sprague-Dawley rats were randomly divided into five groups: Normal + phosphate-buffered saline (PBS), middle cerebral artery occlusion (MCAO) + PBS, Normal + BMSCs, MCAO + BMSCs and MCAO + IL-1ra (an antagonist of IL-1β). BMSCs were transplanted 24 hours after MCAO, and brain edema was evaluated by Magnetic Resonance Imaging (MRI) and brain water content method after BMSCs transplantation. The expression of NeuN and AQP4 was analyzed by immunofluorescence staining. Protein level of AQP4 and IL-1β was detected by western blot analysis 48 hours after transplantation. The results showed that BMSCs transplantation reduced brain edema by measurement of brain water content and ADC Value of MRI, as well as the expression of AQP4 and IL-1β. It was also found that BMSCs transplantation could alleviate the cerebral infarction volume and neuronal damage. Both the brain edema and the cerebral infarction were associated with IL-1β expression. In conclusion, BMSCs transplantation was capable of alleviating brain edema as well as reducing cerebral infarction via down-regulation of IL-1β expression, thus repair the injured brain in focal cerebral ischemic rats. PMID:27186280

  1. Iodoamphetamine as a new tracer for local cerebral blood flow in the rat: comparison with isopropyliodoamphetamine.

    PubMed

    Rapin, J R; Le Poncin-Lafitte, M; Duterte, D; Rips, R; Morier, E; Lassen, N A

    1984-06-01

    Rats were injected with iodoamphetamine synthesized and labeled with 125I or with 125I- isopropyliodoamphetamine , a molecule of established value for the determination of local cerebral blood flow. The blood kinetics, tissue distribution, and brain uptake index for each tracer exhibited practically no differences. Autoradiographic quantification of the local cerebral blood flow, calculated according to the microsphere model, produced identical results for both molecules. However, compared with the values reported for other tracers, our values constituted an underestimation of white matter blood flow and a more real estimation of hippocampal flow. It is concluded from the brain uptake of the derivatives of both amphetamines during the first minutes following their injection that these tracers can be used as a chemical microembolus for the measurement of local cerebral blood flow. PMID:6725437

  2. Iodoamphetamine as a new tracer for local cerebral blood flow in the rat: comparison with isopropyliodoamphetamine

    SciTech Connect

    Rapin, J.R.; Le Poncin-Lafitte, M.; Duterte, D.; Rips, R.; Morier, E.; Lassen, N.A.

    1984-06-01

    Rats were injected with iodoamphetamine synthesized and labeled with /sup 125/I or with /sup 125/I- isopropyliodoamphetamine, a molecule of established value for the determination of local cerebral blood flow. The blood kinetics, tissue distribution, and brain uptake index for each tracer exhibited practically no differences. Autoradiographic quantification of the local cerebral blood flow, calculated according to the microsphere model, produced identical results for both molecules. However, compared with the values reported for other tracers, our values constituted an underestimation of white matter blood flow and a more real estimation of hippocampal flow. It is concluded from the brain uptake of the derivatives of both amphetamines during the first minutes following their injection that these tracers can be used as a chemical microembolus for the measurement of local cerebral blood flow.

  3. Engineering vascularized soft tissue flaps in an animal model using human adipose-derived stem cells and VEGF+PLGA/PEG microspheres on a collagen-chitosan scaffold with a flow-through vascular pedicle.

    PubMed

    Zhang, Qixu; Hubenak, Justin; Iyyanki, Tejaswi; Alred, Erik; Turza, Kristin C; Davis, Greg; Chang, Edward I; Branch-Brooks, Cynthia D; Beahm, Elisabeth K; Butler, Charles E

    2015-12-01

    Insufficient neovascularization is associated with high levels of resorption and necrosis in autologous and engineered fat grafts. We tested the hypothesis that incorporating angiogenic growth factor into a scaffold-stem cell construct and implanting this construct around a vascular pedicle improves neovascularization and adipogenesis for engineering soft tissue flaps. Poly(lactic-co-glycolic-acid/polyethylene glycol (PLGA/PEG) microspheres containing vascular endothelial growth factor (VEGF) were impregnated into collagen-chitosan scaffolds seeded with human adipose-derived stem cells (hASCs). This setup was analyzed in vitro and then implanted into isolated chambers around a discrete vascular pedicle in nude rats. Engineered tissue samples within the chambers were harvested and analyzed for differences in vascularization and adipose tissue growth. In vitro testing showed that the collagen-chitosan scaffold provided a supportive environment for hASC integration and proliferation. PLGA/PEG microspheres with slow-release VEGF had no negative effect on cell survival in collagen-chitosan scaffolds. In vivo, the system resulted in a statistically significant increase in neovascularization that in turn led to a significant increase in adipose tissue persistence after 8 weeks versus control constructs. These data indicate that our model-hASCs integrated with a collagen-chitosan scaffold incorporated with VEGF-containing PLGA/PEG microspheres supported by a predominant vascular vessel inside a chamber-provides a promising, clinically translatable platform for engineering vascularized soft tissue flap. The engineered adipose tissue with a vascular pedicle could conceivably be transferred as a vascularized soft tissue pedicle flap or free flap to a recipient site for the repair of soft-tissue defects.

  4. Chromogranin A-derived peptides: interaction with the rat posterior cerebral artery.

    PubMed

    Mandalà, Maurizio; Brekke, Johan Fredrik; Serck-Hanssen, Guldborg; Metz-Boutigue, Marie-Hélène; Helle, Karen B

    2005-01-15

    Chromogranin A (CgA), an acidic granule protein of the regulated secretory pathway in the diffuse neuroendocrine system, is postulated to serve as a prohormone for regulatory peptides. Betagranin (rCgA(1-128)), the first N-terminal cleavage product of rat CgA, is 87% homologous to the bovine vasostatin I (bCgA(1-76)), previously shown to be vasoinhibitory in bovine resistance arteries. In this study the vasoactivity of homologous rat and bovine peptides was investigated in the rat posterior cerebral artery. Firstly, we examined the interaction of rhodamine (Rh)-labelled bCgA(7-40) and bCgA(47-70) with elements of the arterial wall by fluorescence microscopy. Secondly, rCgA(7-57), bCgA(1-40), bCgA(7-40) and bCgA(47-66) (chromofungin) were studied for effects on arterial tone and intracellular calcium as function of pressure in an arteriograph. Although without dilator or constrictor responses at 60-150 mm Hg, the rat peptide (rCgA(7-57)) evoked a significant delay in the onset of forced dilatation at 170 mm Hg, in contrast to the bovine peptides bCgA(1-40), bCgA(7-40) and bCgA(47-66) (chromofungin). Neither Rh-bCgA(7-40) nor Rh-bCgA(47-70) stained the endothelial layer, while Rh-bCgA(47-70) but not Rh-bCgA(7-40) stained the smooth muscle compartment. Analogously, bCgA(47-66) but not bCgA(7-40) reduced intracellular calcium, however without modifying the myogenic response. Thus, the betagranin peptide rCgA(7-57) and the two bovine chromofungin-containing peptides, highly homologous to the corresponding sequence (rCgA(47-66)), affected the rat cerebral artery without vasodilator effects, indicating significant species differences in vasoactivity of the N-terminal domain of CgA.

  5. Production of hollow aerogel microspheres

    DOEpatents

    Upadhye, Ravindra S.; Henning, Sten A.

    1993-01-01

    A method is described for making hollow aerogel microspheres of 800-1200 .mu. diameter and 100-300 .mu. wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  6. Production of hollow aerogel microspheres

    SciTech Connect

    Upadhye, R.S.; Henning, S.A.

    1990-12-31

    A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

  7. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolysis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  8. Metabolism of proteinoid microspheres

    NASA Technical Reports Server (NTRS)

    Nakashima, T.; Fox, S. W. (Principal Investigator)

    1987-01-01

    The literature of metabolism in proteinoids and proteinoid microspheres is reviewed and criticized from a biochemical and experimental point of view. Closely related literature is also reviewed in order to understand the function of proteinoids and proteinoid microspheres. Proteinoids or proteinoid microspheres have many activities. Esterolyis, decarboxylation, amination, deamination, and oxidoreduction are catabolic enzyme activities. The formation of ATP, peptides or oligonucleotides is synthetic enzyme activities. Additional activities are hormonal and inhibitory. Selective formation of peptides is an activity of nucleoproteinoid microspheres; these are a model for ribosomes. Mechanisms of peptide and oligonucleotide syntheses from amino acids and nucleotide triphosphate by proteinoid microspheres are tentatively proposed as an integrative consequence of reviewing the literature.

  9. The Effects of Antecedent Exercise on Motor Function Recovery and Brain-derived Neurotrophic Factor Expression after Focal Cerebral Ischemia in Rats

    PubMed Central

    Kim, Gyeyeop; Kim, Eunjung

    2013-01-01

    [Purpose] In the present study, we investigated the effect of antecedent exercise on functional recovery and brain-derived neurotrophic factor (BDNF) expression following focal cerebral ischemia injury. [Subjects] The rat middle cerebral artery occlusion (MCAO) model was employed. Adult male Sprague-Dawley rats were randomly divided into 4 groups. Group I included untreated normal rats (n=10); Group II included untreated rats with focal cerebral ischemia (n=10); Group III included rats that performed treadmill exercise (20 m/min) training after focal cerebral ischemia (n=10); and Group IV included rats that performed antecedent treadmill exercise (20 m/min) training before focal cerebral ischemia (n=10) as well as treadmill exercise after ischemia. At different time points (1, 7, 14, and 21 days) Garcia’s score, and the hippocampal expressions level of BDNF were examined. [Results] In the antecedent exercise group, improvements in the motor behavior index (Garcia’s score) were observed and hippocampal BDNF protein expression levels increased. [Conclusion] These results indicate that antecedent treadmill exercise, before permanent brain ischemia exerts a neuroprotective effect against ischemia brain injury by improving motor performance and increasing the level of BDNF expression. Furthermore, the antecedent treadmill exercise of appropriate intensity is critical for post-stroke rehabilitation. PMID:24259800

  10. Microsphere zeolite materials derived from coal fly ash cenospheres as precursors to mineral-like aluminosilicate hosts for 135,137Cs and 90Sr

    NASA Astrophysics Data System (ADS)

    Vereshchagina, Tatiana A.; Vereshchagin, Sergei N.; Shishkina, Nina N.; Vasilieva, Nataly G.; Solovyov, Leonid A.; Anshits, Alexander G.

    2013-06-01

    Hollow microsphere zeolite materials with a bilayered zeolite/glass crystalline shell bearing NaP1 zeolite were synthesized by the hydrothermal treatment of coal fly ash cenospheres (Si/Al = 2.7) in an alkaline medium. Cs+ and/or Sr2+ forms of zeolitized cenospheres with the different Cs+ and/or Sr2+ loading were prepared by the ion exchange from nitrate solutions. The resulted (Cs,Na)P1, (Sr,Na)P1 and (Cs,Sr,Na)P1 bearing microsphere zeolites were converted to glass ceramics by heating at 900-1000 °C. The differential scanning calorimetry and quantitative phase analysis were used to monitor the solid-phase transformation of the initial and ion exchanged zeolite materials. It was established that the final solidified forms of Cs+ and/or Sr2+ are glass-crystalline ceramic materials based on pollucite-nepheline, Sr-feldspar-nepheline and Sr-feldspar-pollucite composites including ˜60 wt.% of the major host phases (pollucite, Sr-feldspar) and 10-20 wt.% of glass. The 137Cs leaching rate of 4.1 × 10-7 g cm-2 day-1 was determined for the pollucite glass-ceramic according to Russian State Standard (GOST) No. 52126 P-2003 (7 day, 25 °C, distilled water).

  11. Characterisation of radioiodinated flavonoid derivatives for SPECT imaging of cerebral prion deposits.

    PubMed

    Fuchigami, Takeshi; Yamashita, Yuki; Kawasaki, Masao; Ogawa, Ayaka; Haratake, Mamoru; Atarashi, Ryuichiro; Sano, Kazunori; Nakagaki, Takehiro; Ubagai, Kaori; Ono, Masahiro; Yoshida, Sakura; Nishida, Noriyuki; Nakayama, Morio

    2015-01-01

    Prion diseases are fatal neurodegenerative diseases characterised by deposition of amyloid plaques containing abnormal prion protein aggregates (PrP(Sc)). This study aimed to evaluate the potential of radioiodinated flavonoid derivatives for single photon emission computed tomography (SPECT) imaging of PrP(Sc). In vitro binding assays using recombinant mouse PrP (rMoPrP) aggregates revealed that the 4-dimethylamino-substituted styrylchromone derivative (SC-NMe2) had higher in vitro binding affinity (Kd = 24.5 nM) and capacity (Bmax = 36.3 pmol/nmol protein) than three other flavonoid derivatives (flavone, chalcone, and aurone). Fluorescent imaging using brain sections from mouse-adapted bovine spongiform encephalopathy (mBSE)-infected mice demonstrated that SC-NMe2 clearly labelled PrP(Sc)-positive prion deposits in the mice brain. Two methoxy SC derivatives, SC-OMe and SC-(OMe)2, also showed high binding affinity for rMoPrP aggregates with Ki values of 20.8 and 26.6 nM, respectively. In vitro fluorescence and autoradiography experiments demonstrated high accumulation of [(125)I]SC-OMe and [(125)I]SC-(OMe)2 in prion deposit-rich regions of the mBSE-infected mouse brain. SPECT/computed tomography (CT) imaging and ex vivo autoradiography demonstrated that [(123)I]SC-OMe showed consistent brain distribution with the presence of PrP(Sc) deposits in the mBSE-infected mice brain. In conclusion, [(123)I]SC-OMe appears a promising SPECT radioligand for monitoring prion deposit levels in the living brain. PMID:26669576

  12. Characterisation of radioiodinated flavonoid derivatives for SPECT imaging of cerebral prion deposits

    PubMed Central

    Fuchigami, Takeshi; Yamashita, Yuki; Kawasaki, Masao; Ogawa, Ayaka; Haratake, Mamoru; Atarashi, Ryuichiro; Sano, Kazunori; Nakagaki, Takehiro; Ubagai, Kaori; Ono, Masahiro; Yoshida, Sakura; Nishida, Noriyuki; Nakayama, Morio

    2015-01-01

    Prion diseases are fatal neurodegenerative diseases characterised by deposition of amyloid plaques containing abnormal prion protein aggregates (PrPSc). This study aimed to evaluate the potential of radioiodinated flavonoid derivatives for single photon emission computed tomography (SPECT) imaging of PrPSc. In vitro binding assays using recombinant mouse PrP (rMoPrP) aggregates revealed that the 4-dimethylamino-substituted styrylchromone derivative (SC-NMe2) had higher in vitro binding affinity (Kd = 24.5 nM) and capacity (Bmax = 36.3 pmol/nmol protein) than three other flavonoid derivatives (flavone, chalcone, and aurone). Fluorescent imaging using brain sections from mouse-adapted bovine spongiform encephalopathy (mBSE)-infected mice demonstrated that SC-NMe2 clearly labelled PrPSc-positive prion deposits in the mice brain. Two methoxy SC derivatives, SC-OMe and SC-(OMe)2, also showed high binding affinity for rMoPrP aggregates with Ki values of 20.8 and 26.6 nM, respectively. In vitro fluorescence and autoradiography experiments demonstrated high accumulation of [125I]SC-OMe and [125I]SC-(OMe)2 in prion deposit-rich regions of the mBSE-infected mouse brain. SPECT/computed tomography (CT) imaging and ex vivo autoradiography demonstrated that [123I]SC-OMe showed consistent brain distribution with the presence of PrPSc deposits in the mBSE-infected mice brain. In conclusion, [123I]SC-OMe appears a promising SPECT radioligand for monitoring prion deposit levels in the living brain. PMID:26669576

  13. Inhalation of water electrolysis-derived hydrogen ameliorates cerebral ischemia-reperfusion injury in rats - A possible new hydrogen resource for clinical use.

    PubMed

    Cui, Jin; Chen, Xiao; Zhai, Xiao; Shi, Dongchen; Zhang, Rongjia; Zhi, Xin; Li, Xiaoqun; Gu, Zhengrong; Cao, Liehu; Weng, Weizong; Zhang, Jun; Wang, Liping; Sun, Xuejun; Ji, Fang; Hou, Jiong; Su, Jiacan

    2016-10-29

    Hydrogen is a kind of noble gas with the character to selectively neutralize reactive oxygen species. Former researches proved that low-concentration of hydrogen can be used to ameliorating cerebral ischemia/reperfusion injury. Hydrogen electrolyzed from water has a hydrogen concentration of 66.7%, which is much higher than that used in previous studies. And water electrolysis is a potential new hydrogen resource for regular clinical use. This study was designed and carried out for the determination of safety and neuroprotective effects of water electrolysis-derived hydrogen. Sprague-Dawley rats were used as experimental animals, and middle cerebral artery occlusion was used to make cerebral ischemia/reperfusion model. Pathologically, tissues from rats in hydrogen inhalation group showed no significant difference compared with the control group in HE staining pictures. The blood biochemical findings matched the HE staining result. TTC, Nissl, and TUNEL staining showed the significant improvement of infarction volume, neuron morphology, and neuron apoptosis in rat with hydrogen treatment. Biochemically, hydrogen inhalation decreased brain caspase-3, 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine-positive cells and inflammation factors concentration. Water electrolysis-derived hydrogen inhalation had neuroprotective effects on cerebral ischemia/reperfusion injury in rats with the effect of suppressing oxidative stress and inflammation, and it is a possible new hydrogen resource to electrolyze water at the bedside clinically. PMID:27555551

  14. Inhalation of water electrolysis-derived hydrogen ameliorates cerebral ischemia-reperfusion injury in rats - A possible new hydrogen resource for clinical use.

    PubMed

    Cui, Jin; Chen, Xiao; Zhai, Xiao; Shi, Dongchen; Zhang, Rongjia; Zhi, Xin; Li, Xiaoqun; Gu, Zhengrong; Cao, Liehu; Weng, Weizong; Zhang, Jun; Wang, Liping; Sun, Xuejun; Ji, Fang; Hou, Jiong; Su, Jiacan

    2016-10-29

    Hydrogen is a kind of noble gas with the character to selectively neutralize reactive oxygen species. Former researches proved that low-concentration of hydrogen can be used to ameliorating cerebral ischemia/reperfusion injury. Hydrogen electrolyzed from water has a hydrogen concentration of 66.7%, which is much higher than that used in previous studies. And water electrolysis is a potential new hydrogen resource for regular clinical use. This study was designed and carried out for the determination of safety and neuroprotective effects of water electrolysis-derived hydrogen. Sprague-Dawley rats were used as experimental animals, and middle cerebral artery occlusion was used to make cerebral ischemia/reperfusion model. Pathologically, tissues from rats in hydrogen inhalation group showed no significant difference compared with the control group in HE staining pictures. The blood biochemical findings matched the HE staining result. TTC, Nissl, and TUNEL staining showed the significant improvement of infarction volume, neuron morphology, and neuron apoptosis in rat with hydrogen treatment. Biochemically, hydrogen inhalation decreased brain caspase-3, 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine-positive cells and inflammation factors concentration. Water electrolysis-derived hydrogen inhalation had neuroprotective effects on cerebral ischemia/reperfusion injury in rats with the effect of suppressing oxidative stress and inflammation, and it is a possible new hydrogen resource to electrolyze water at the bedside clinically.

  15. Organic aerogel microspheres

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  16. Organic aerogel microspheres

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  17. Method for sizing hollow microspheres

    DOEpatents

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  18. Cerebral Palsy

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Cerebral Palsy KidsHealth > For Teens > Cerebral Palsy Print A A ... do just what everyone else does. What Is Cerebral Palsy? Cerebral palsy (CP) is a disorder of the ...

  19. Method for preparing hollow metal oxide microsphere

    DOEpatents

    Schmitt, C.R.

    1974-02-12

    Hollow refractory metal oxide microspheres are prepared by impregnating resinous microspheres with a metallic compound, drying the impregnated microspheres, heating the microspheres slowly to carbonize the resin, and igniting the microspheres to remove the carbon and to produce the metal oxide. Zirconium oxide is given as an example. (Official Gazette)

  20. Protections of SMND-309, a novel derivate of salvianolic acid B, on brain mitochondria contribute to injury amelioration in cerebral ischemia rats.

    PubMed

    Tian, Jingwei; Fu, Fenghua; Li, Guisheng; Gao, Yubai; Zhang, Yunjuan; Meng, Qingsheng; Li, Changlu; Liu, Fu

    2009-08-01

    SMND-309, a novel compound named (2E)-2-{6-[(E)-2-carboxylvinyl]-2,3-dihydroxyphenyl}-3-(3,4-dihydroxyphenyl) propenoic acid, is a new derivate of salvianolic acid B. The present study was conducted to investigate whether SMND-309 has a protective effect on brain injury after focal cerebral ischemia, and if it did so, to investigate its effects on brain mitochondria. Adult male SD rats were subjected to middle cerebral artery occlusion (MCAO) by bipolar electro-coagulation. Behavioral tests and brain patho-physiological tests were used to evaluate the damage to central nervous system. Origin targets including mitochondria production of reactive oxygen species, antioxidant potentia, membrane potential, energy metabolism, mitochondrial respiratory enzymes activities and mitochondria swelling degree were evaluated. The results showed that SMND-309 decreased neurological deficit scores, reduced the number of dead hippocampal neuronal cells in accordance with its depression on mitochondria swelling degree, reactive oxygen species production, improvements on mitochondria swelling, energy metabolism, membrane potential level and mitochondrial respiratory chain complex activities. All of these findings indicate that SMND-309 exerted potent neuroprotective effects in the model of permanent cerebral ischemia, contributed to its protections on brain mitochondrial structure and function. PMID:19481432

  1. Protections of SMND-309, a novel derivate of salvianolic acid B, on brain mitochondria contribute to injury amelioration in cerebral ischemia rats.

    PubMed

    Tian, Jingwei; Fu, Fenghua; Li, Guisheng; Gao, Yubai; Zhang, Yunjuan; Meng, Qingsheng; Li, Changlu; Liu, Fu

    2009-08-01

    SMND-309, a novel compound named (2E)-2-{6-[(E)-2-carboxylvinyl]-2,3-dihydroxyphenyl}-3-(3,4-dihydroxyphenyl) propenoic acid, is a new derivate of salvianolic acid B. The present study was conducted to investigate whether SMND-309 has a protective effect on brain injury after focal cerebral ischemia, and if it did so, to investigate its effects on brain mitochondria. Adult male SD rats were subjected to middle cerebral artery occlusion (MCAO) by bipolar electro-coagulation. Behavioral tests and brain patho-physiological tests were used to evaluate the damage to central nervous system. Origin targets including mitochondria production of reactive oxygen species, antioxidant potentia, membrane potential, energy metabolism, mitochondrial respiratory enzymes activities and mitochondria swelling degree were evaluated. The results showed that SMND-309 decreased neurological deficit scores, reduced the number of dead hippocampal neuronal cells in accordance with its depression on mitochondria swelling degree, reactive oxygen species production, improvements on mitochondria swelling, energy metabolism, membrane potential level and mitochondrial respiratory chain complex activities. All of these findings indicate that SMND-309 exerted potent neuroprotective effects in the model of permanent cerebral ischemia, contributed to its protections on brain mitochondrial structure and function.

  2. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1980-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  3. Polyvinyl pyridine microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Gupta, Amitava (Inventor); Volksen, Willi (Inventor)

    1979-01-01

    Microspheres are produced by cobalt gamma radiation initiated polymerization of a dilute aqueous vinyl pyridine solution. Addition of cross-linking agent provides higher surface area beads. Addition of monomers such as hydroxyethylmethacrylate acrylamide or methacrylamide increases hydrophilic properties and surface area of the beads. High surface area catalytic supports are formed in the presence of controlled pore glass substrate.

  4. Doped zinc oxide microspheres

    DOEpatents

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  5. Doped zinc oxide microspheres

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-12-14

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  6. Microsphere insulation systems

    NASA Technical Reports Server (NTRS)

    Allen, Mark S. (Inventor); Willen, Gary S. (Inventor); Mohling, Robert A. (Inventor)

    2005-01-01

    A new insulation system is provided that contains microspheres. This insulation system can be used to provide insulated panels and clamshells, and to insulate annular spaces around objects used to transfer, store, or transport cryogens and other temperature-sensitive materials. This insulation system provides better performance with reduced maintenance than current insulation systems.

  7. Fusion microsphere targets

    SciTech Connect

    Koo, J.C.

    1980-07-28

    It was shown that a microsphere within the structure limitations is hydrodynamically stable. To insure its perfect formation, the initial chemical compositions must have a blowing capability, more important, the resultant liquid compositions must also have sufficient surface tension and low viscosity.

  8. Cerebral Hypoxia

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Cerebral Hypoxia Information Page Synonym(s): Hypoxia, Anoxia Table of Contents ( ... Trials Organizations Publicaciones en Español What is Cerebral Hypoxia? Cerebral hypoxia refers to a condition in which ...

  9. Porous microsphere and its applications

    PubMed Central

    Cai, Yunpeng; Chen, Yinghui; Hong, Xiaoyun; Liu, Zhenguo; Yuan, Weien

    2013-01-01

    Porous microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of porous microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the porous microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies. PMID:23515359

  10. Functional magnetic microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Landel, Robert F. (Inventor)

    1981-01-01

    Functional magnetic particles are formed by dissolving a mucopolysaccharide such as chitosan in acidified aqueous solution containing a mixture of ferrous chloride and ferric chloride. As the pH of the solution is raised magnetite is formed in situ in the solution by raising the pH. The dissolved chitosan is a polyelectrolyte and forms micelles surrounding the granules at pH of 8-9. The chitosan precipitates on the granules to form microspheres containing the magnetic granules. On addition of the microspheres to waste aqueous streams containing dissolved ions, the hydroxyl and amine functionality of the chitosan forms chelates binding heavy metal cations such as lead, copper, and mercury and the chelates in turn bind anions such as nitrate, fluoride, phosphate and borate.

  11. Microbiological and clinical effects of enamel matrix derivative and sustained-release micro-spherical minocycline application as an adjunct to non-surgical therapy in peri-implant mucosal inflammation

    PubMed Central

    Goharfar, Zahra; Pourabbas, Reza; Kashefimehr, Atabak; Shirmohmmadi, Adileh

    2015-01-01

    Objectives The purpose of this study was to compare the microbial and clinical effects of mechanical debridement (MD) alone or in combination with the application of enamel matrix derivative (EMD) and sustained-release micro-spherical minocycline (MSM) for treatment of peri-implant mucosal infl ammation (PIMI). Materials and Methods Subjects with at least one implant with PIMI were included and divided into control and two different test groups. In all three groups, MD was performed. In the MSM group, following MD, MSM was placed subgingivally around the implants. In the EMD group, after MD, EMD was placed in the sulcus around the implants. Sampling of peri-implant crevicular fl uid for microbial analysis with real-time polymerase chain reaction and recording of probing depth (PD) and bleeding on probing (BOP) were performed prior to as well as two weeks and three months after treatment. Median values and interquartile range were estimated for each variable during the various assessment intervals of the study. Results In all groups, at two weeks and three months, the counts of Porphyromonas gingivalis decreased significantly compared to baseline. Levels of P. gingivalis were significantly reduced in MSM (P<0.001) and EMD (P=0.026) groups compared to the control group. Also, clinical parameters improved significantly at two weeks and three months. Reduction of PD was significant in MSM (P<0.001) and EMD (P<0.001) groups. The decrease in BOP in the MSM, EMD, and control groups was 60%, 50%, and 20%, respectively. Conclusion The use of MSM and EMD can be an adjunctive treatment for management of PIMI and improves clinical parameters and reduces P. gingivalis burden three months after treatment. PMID:26339576

  12. Imaging the time-integrated cerebral metabolic activity with subcellular resolution through nanometer-scale detection of biosynthetic products deriving from (13)C-glucose.

    PubMed

    Takado, Yuhei; Knott, Graham; Humbel, Bruno M; Masoodi, Mojgan; Escrig, Stéphane; Meibom, Anders; Comment, Arnaud

    2015-11-01

    Glucose is the primary source of energy for the brain but also an important source of building blocks for proteins, lipids, and nucleic acids. Little is known about the use of glucose for biosynthesis in tissues at the cellular level. We demonstrate that local cerebral metabolic activity can be mapped in mouse brain tissue by quantitatively imaging the biosynthetic products deriving from [U-(13)C]glucose metabolism using a combination of in situ electron microscopy and secondary ion mass-spectroscopy (NanoSIMS). Images of the (13)C-label incorporated into cerebral ultrastructure with ca. 100 nm resolution allowed us to determine the timescale on which the metabolic products of glucose are incorporated into different cells, their sub-compartments and organelles. These were mapped in astrocytes and neurons in the different layers of the motor cortex. We see evidence for high metabolic activity in neurons via the nucleus (13)C enrichment. We observe that in all the major cell compartments, such as e.g. nucleus and Golgi apparatus, neurons incorporate substantially higher concentrations of (13)C-label than astrocytes. PMID:26409162

  13. Quantitative agreement between [(15)O]H2O PET and model free QUASAR MRI-derived cerebral blood flow and arterial blood volume.

    PubMed

    Heijtel, D F R; Petersen, E T; Mutsaerts, H J M M; Bakker, E; Schober, P; Stevens, M F; van Berckel, B N M; Majoie, C B L M; Booij, J; van Osch, M J P; van Bavel, E T; Boellaard, R; Lammertsma, A A; Nederveen, A J

    2016-04-01

    The purpose of this study was to assess whether there was an agreement between quantitative cerebral blood flow (CBF) and arterial cerebral blood volume (CBVA) measurements by [(15)O]H2O positron emission tomography (PET) and model-free QUASAR MRI. Twelve healthy subjects were scanned within a week in separate MRI and PET imaging sessions, after which quantitative and qualitative agreement between both modalities was assessed for gray matter, white matter and whole brain region of interests (ROI). The correlation between CBF measurements obtained with both modalities was moderate to high (r(2): 0.28-0.60, P < 0.05), although QUASAR significantly underestimated CBF by 30% (P < 0.001). CBVA was moderately correlated (r(2): 0.28-0.43, P < 0.05), with QUASAR yielding values that were only 27% of the [(15)O]H2O-derived values (P < 0.001). Group-wise voxel statistics identified minor areas with significant contrast differences between [(15)O]H2O PET and QUASAR MRI, indicating similar qualitative CBVA and CBF information by both modalities. In conclusion, the results of this study demonstrate that QUASAR MRI and [(15)O]H2O PET provide similar CBF and CBVA information, but with systematic quantitative discrepancies.

  14. Metal containing polymeric functional microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1979-01-01

    Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing. After collection of the labeled cells, the magnetic field is discontinued and the labeled sub-cell population recovered.

  15. Immunofluorescence detection methods using microspheres

    NASA Astrophysics Data System (ADS)

    Szurdoki, Ferenc; Michael, Karri L.; Agrawal, Divya; Taylor, Laura C.; Schultz, Sandra L.; Walt, David R.

    1999-01-01

    Microsphere-based immunoassays were devised for compounds of agricultural and biomedical interest (e.g., digoxin, theophylline, and zearalenone). Commercially available microspheres with surface functional groups for chemical derivatization were used as solid carriers. After immobilizing the target substances, the surface of the haptenized microspheres was blocked by a protein to reduce aspecific binding. Competitive immunoassays were performed using the functionalized microspheres and antibodies labeled with horseradish peroxidase. Immunofluorescence signal amplification was achieved by enzyme-catalyzed reporter deposition (CARD). An epifluorescence microscope, a CCD camera interfaced with a computer, and microscopy image analysis software were employed for quantitative detection of fluorescent light emitted from individual microspheres. Integration of several such immunoassays and application of an optical encoding method enabled multianalyte determination. These immunoassays can also be utilized in an immunosensor array format. This immunoarray format could facilitate miniaturization and automation of multianalyte immunoassays.

  16. Dose calculation of 142Pr microspheres as a potential treatment for arteriovenous malformations

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Woo; Reece, Warren Daniel

    2005-01-01

    Arteriovenous malformation (AVM), especially cryptic AVM, can cause highly variable cerebral neurological defects. Injection of 142Pr microspheres into arteries feeding an AVM in order to simulate radio-embolism has been proposed as a novel treatment method. To investigate optimization of radiation dose to the clinically important arterial wall area, preliminary dosimetric studies have been performed. Monte Carlo calculations were performed for simulated arteries filled with microspheres packed by random packing. Arterial radii from 0.05 mm to 3 mm and microsphere radii from 0.01 mm to 0.7 mm were used in the simulation. For constant arterial size, dose varied significantly with microspheres radius. Inter-arterial effect was also simulated using simplified geometry. For the inter-arterial sites, the dose rate was calculated between two arteries of the same size parallel to each other. The dose increased significantly for large arteries (>1 mm radius) filled with large microspheres (>0.3 mm radius). The dose increase between small arteries (<0.3 mm radius) was not as significant as that between large arteries. Overall results indicate that arterial size and microsphere size significantly affect the dose profile. This factor should be taken into account in future clinical applications.

  17. In vitro and in vivo evaluation of biodegradable embolic microspheres with tunable anticancer drug release.

    PubMed

    Weng, Lihui; Rostamzadeh, Parinaz; Nooryshokry, Navid; Le, Hung C; Golzarian, Jafar

    2013-06-01

    Natural polymer-derived materials have attracted increasing interest in the biomedical field. Polysaccharides have obvious advantages over other polymers employed for biomedical applications due to their exceptional biocompatibility and biodegradability. None of the spherical embolic agents used clinically is biodegradable. In the current study, microspheres prepared from chitosan and carboxymethyl cellulose (CMC) were investigated as a biodegradable embolic agent for arterial embolization applications. Aside from the enzymatic degradability of chitosan units, the cross-linking bonds in the matrix, Schiff bases, are susceptible to hydrolytic cleavage in aqueous conditions, which would overcome the possible shortage of enzymes inside the arteries. The size distribution, morphology, water retention capacity and degradability of the microspheres were found to be affected by the modification degree of CMC. An anticancer drug, doxorubicin, was successfully incorporated into these microspheres for local release and thus for killing cancerous cells. These microspheres demonstrated controllable degradation time, variable swelling and tunable drug release profiles. Co-culture with human umbilical vein endothelial cells revealed non-cytotoxic nature of these microspheres compared to monolayer control (P>0.95). In addition, a preliminary study on the in vivo degradation of the microspheres (100-300μm) was performed in a rabbit renal embolization model, which demonstrated that the microspheres were compatible with microcatheters for delivery, capable of occluding the arteries, and biodegradable inside arteries. These microspheres with biodegradability would be promising for embolization therapies. PMID:23419554

  18. Hydrostatic determinants of cerebral perfusion

    SciTech Connect

    Wagner, E.M.; Traystman, R.J.

    1986-05-01

    We examined the cerebral blood flow response to alterations in perfusion pressure mediated through decreases in mean arterial pressure, increases in cerebrospinal fluid (CSF) pressure, and increases in jugular venous (JV) pressure in 42 pentobarbital anesthetized dogs. Each of these three pressures was independently controlled. Cerebral perfusion pressure was defined as mean arterial pressure minus JV or CSF pressure, depending on which was greater. Mean hemispheric blood flow was measured with the radiolabeled microsphere technique. Despite 30-mm Hg reductions in mean arterial pressure or increases in CSF or JV pressure, CBF did not change as long as the perfusion pressure remained greater than approximately 60 mm Hg. However, whenever perfusion pressure was reduced to an average of 48 mm Hg, cerebral blood flow decreased 27% to 33%. These results demonstrate the capacity of the cerebral vascular bed to respond similarly to changes in the perfusion pressure gradient obtained by decreasing mean arterial pressure, increasing JV pressure or increasing CSF pressure, and thereby support the above definition of cerebral perfusion pressure.

  19. Carboxymethyldextran/magnetite hybrid microspheres designed for hyperthermia.

    PubMed

    Miyazaki, Toshiki; Anan, Shota; Ishida, Eiichi; Kawashita, Masakazu

    2013-05-01

    Recently, organic-inorganic hybrids composed of derivatives of dextran, a polysaccharide, and magnetite nanoparticles have attracted much attention as novel thermoseeds. If they can be fabricated into microspheres of size 20-30 μm, they are expected to show not only hyperthermia effects but also embolization effects in human liver and kidney cancers. In this study, we examined the fabrication of carboxymethyldextran/magnetite microspheres using a water/oil emulsion as the reaction medium. Improvement of the chemical stability of the microcapsules by coating with silica using a sol-gel process was also investigated. The obtained hollow microspheres contained particles of size 20-30 μm. Silica coating using an appropriate catalyst for hydrolysis and polycondensation of alkoxysilanes was found to be effective for preventing dissolution and collapse in simulated body environments.

  20. Carboxymethyldextran/magnetite hybrid microspheres designed for hyperthermia.

    PubMed

    Miyazaki, Toshiki; Anan, Shota; Ishida, Eiichi; Kawashita, Masakazu

    2013-05-01

    Recently, organic-inorganic hybrids composed of derivatives of dextran, a polysaccharide, and magnetite nanoparticles have attracted much attention as novel thermoseeds. If they can be fabricated into microspheres of size 20-30 μm, they are expected to show not only hyperthermia effects but also embolization effects in human liver and kidney cancers. In this study, we examined the fabrication of carboxymethyldextran/magnetite microspheres using a water/oil emulsion as the reaction medium. Improvement of the chemical stability of the microcapsules by coating with silica using a sol-gel process was also investigated. The obtained hollow microspheres contained particles of size 20-30 μm. Silica coating using an appropriate catalyst for hydrolysis and polycondensation of alkoxysilanes was found to be effective for preventing dissolution and collapse in simulated body environments. PMID:23371771

  1. A facile one-pot sonochemical synthesis of surface-coated mannosyl protein microspheres for detection and killing of bacteria.

    PubMed

    Skirtenko, Natalia; Richman, Michal; Nitzan, Yeshayahu; Gedanken, Aharon; Rahimipour, Shai

    2011-12-01

    We report a remarkably facile one-pot sonochemical approach to prepare protein microspheres whose shells are covalently decorated with a mannosyl derivative to target Escherichia coli (E. coli), while their cores are encapsulated with tetracycline. Conjugated microspheres induced the agglutination of E. coli and increased the anti-bacterial activity of the encapsulated tetracycline by five fold.

  2. Towards Monodispersed Polymer Microspheres

    NASA Astrophysics Data System (ADS)

    Senuma, Yoshinori; Hilborn, Jons

    1998-03-01

    Uniform polymer microspheres prepared by Spinning Disk Atomization Our spinning disk atomization (SDA) can, relative to other existing techniques, produce micron-sized particles of very narrow size distribution. Around the edge of the disk, small teeth channel the flow into identical droplets that are flung off over the disk rim. These solidify during flight to form spherical particles. Applications for spheres produced by SDA can be found in areas such as adhesives, powder coatings, food, biomedical use, drug delivery systems, etc. We have atomized polyethyleneglycol into very narrowly dispersed microspheres ranging from 50 to 500 =B5m. The aim of this work is to model the droplet formation occurring at the rim of the spinning disk in order to better understand the experimental results. The viscosity contribution in the fluid breakup is qualitatively analyzed and is adapted to the theoretical model to show how it affects the droplet size. We have used the pendant drop model (Ramesh Babu, S. Journal of Colloid and Interface Science 116, 350-372 (1987).) for spinning disk atomization to describe the drop-shape evolution during growth.

  3. Convective microsphere monolayer deposition

    NASA Astrophysics Data System (ADS)

    Gilchrist, James

    2011-03-01

    There is perhaps no simpler way of modifying surface chemistry and morphology than surface deposition of particles. Micron-sized microspheres were deposited into thin films via rapid convective deposition, similar to the `coffee ring effect' using a similar method to that studied by Prevo and Velev, Langmuir, 2003. By varying deposition rate and blade angle, the optimal operating ranges in which 2D close-packed arrays of microspheres existed were obtained. Self-assembly of colloidal particles through a balance of electrostatic and capillary forces during solvent evaporation was revealed. These interactions were explored through a model comparing the residence time of a particle in the thin film and the characteristic time of capillary-driven crystallization to describe the morphology and microstructure of deposited particles. Co-deposition of binary suspensions of micron and nanoscale particles was tailored to generate higher-quality surface coatings and a simple theory describes the immergence of instabilities that result in formation of stripes. Optical and biomedical applications that utilize the described nanoscale control over surface morphology will also be discussed.

  4. Microsphere based saliva diagnostics

    NASA Astrophysics Data System (ADS)

    Rissin, David M.; DiCesare, Christopher; Hayman, Ryan B.; Blicharz, Timothy M.; Walt, David R.

    2005-11-01

    Saliva presents a minimally invasive alternative medium to blood for performing diagnostics1. Microsphere sensors for ions, small organic molecules, and proteins are currently being developed and optical microarrays containing thousands of these sensors will be used for simultaneous multi-analyte analysis. The fiber bundle platform in use is 1mm in diameter and contains approximately 50,000 individually addressable 3.1μm fibers, each with an etched well capable of housing a single 3.1μm microsphere sensor. Micron-sized bead-based chemistries are produced in house, followed by deposition onto a fiber-optic bundle platform, allowing for multiplexed analysis. The ultimate goal is to develop a universal diagnostic system using saliva as the diagnostic medium. This platform will permit multiplexed analysis of a sample by integrating microfluidics with the optical arrays loaded with sensors capable of detecting relevant biomarkers associated with a wide range of disease states. Disease states that are currently under investigation include end stage renal disease (ESRD) and Sjoegrens Syndrome (SS).

  5. Cerebral Palsy

    MedlinePlus

    ... Got Homework? Here's Help White House Lunch Recipes Cerebral Palsy KidsHealth > For Kids > Cerebral Palsy Print A A ... the things that kids do every day. What's CP? Some kids with CP use wheelchairs and others ...

  6. Cerebral Palsy

    MedlinePlus

    ... Loss > Birth defects & other health conditions > Cerebral palsy Cerebral palsy E-mail to a friend Please fill in ... movement problems a child has. What is spastic CP? Spastic means tight or stiff muscles, or muscles ...

  7. Cerebral Palsy

    MedlinePlus

    Cerebral palsy is a group of disorders that affect a person's ability to move and to maintain balance ... do not get worse over time. People with cerebral palsy may have difficulty walking. They may also have ...

  8. Mechanical Injury Induces Brain Endothelial-Derived Microvesicle Release: Implications for Cerebral Vascular Injury during Traumatic Brain Injury.

    PubMed

    Andrews, Allison M; Lutton, Evan M; Merkel, Steven F; Razmpour, Roshanak; Ramirez, Servio H

    2016-01-01

    . These results indicate that following TBI, the cerebral endothelium undergoes vascular remodeling through shedding of eMVs containing TJPs and endothelial markers. The detection of this shedding potentially allows for a novel methodology for real-time monitoring of cerebral vascular health (remodeling), BBB status and neuroinflammation following a TBI event. PMID:26973460

  9. Mechanical Injury Induces Brain Endothelial-Derived Microvesicle Release: Implications for Cerebral Vascular Injury during Traumatic Brain Injury

    PubMed Central

    Andrews, Allison M.; Lutton, Evan M.; Merkel, Steven F.; Razmpour, Roshanak; Ramirez, Servio H.

    2016-01-01

    . These results indicate that following TBI, the cerebral endothelium undergoes vascular remodeling through shedding of eMVs containing TJPs and endothelial markers. The detection of this shedding potentially allows for a novel methodology for real-time monitoring of cerebral vascular health (remodeling), BBB status and neuroinflammation following a TBI event. PMID:26973460

  10. Cerebral Palsy

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS NINDS Cerebral Palsy Information Page Clinical Trials Trial of Erythropoietin Neuroprotection ... en Español Additional resources from MedlinePlus What is Cerebral Palsy? The term cerebral palsy refers to a group ...

  11. Cerebral Aneurysms

    MedlinePlus

    ... Enhancing Diversity Find People About NINDS NINDS Cerebral Aneurysms Information Page Synonym(s): Aneurysm, Brain Aneurysm Condensed from ... Español Additional resources from MedlinePlus What is Cerebral Aneurysms? A cerebral aneurysm is a weak or thin ...

  12. A tetracycline derivative, minocycline, reduces inflammation and protects against focal cerebral ischemia with a wide therapeutic window

    PubMed Central

    Yrjänheikki, Juha; Tikka, Tiina; Keinänen, Riitta; Goldsteins, Gundars; Chan, Pak H.; Koistinaho, Jari

    1999-01-01

    The only treatment of patients with acute ischemic stroke is thrombolytic therapy, which benefits only a fraction of stroke patients. Both human and experimental studies indicate that ischemic stroke involves secondary inflammation that significantly contributes to the outcome after ischemic insult. Minocycline is a semisynthetic second-generation tetracycline that exerts antiinflammatory effects that are completely separate from its antimicrobial action. Because tetracycline treatment is clinically well tolerated, we investigated whether minocycline protects against focal brain ischemia with a wide therapeutic window. Using a rat model of transient middle cerebral artery occlusion, we show that daily treatment with minocycline reduces cortical infarction volume by 76 ± 22% when the treatment is started 12 h before ischemia and by 63 ± 35% when started even 4 h after the onset of ischemia. The treatment inhibits morphological activation of microglia in the area adjacent to the infarction, inhibits induction of IL-1β-converting enzyme, and reduces cyclooxygenase-2 expression and prostaglandin E2 production. Minocycline had no effect on astrogliosis or spreading depression, a wave of ionic transients thought to contribute to enlargement of cortical infarction. Treatment with minocycline may act directly on brain cells, because cultured primary neurons were also salvaged from glutamate toxicity. Minocycline may represent a prototype of an antiinflammatory compound that provides protection against ischemic stroke and has a clinically relevant therapeutic window. PMID:10557349

  13. Novel pentameric thiophene derivatives for in vitro and in vivo optical imaging of a plethora of protein aggregates in cerebral amyloidoses

    PubMed Central

    Åslund, Andreas; Sigurdson, Christina J.; Klingstedt, Therése; Grathwohl, Stefan; Bolmont, Tristan; Dickstein, Dara L.; Glimsdal, Eirik; Prokop, Stefan; Lindgren, Mikael; Konradsson, Peter; Holtzman, David M.; Hof, Patrick R.; Heppner, Frank L.; Gandy, Samuel; Jucker, Mathias; Aguzzi, Adriano; Hammarström, Per; Nilsson, K. Peter R.

    2010-01-01

    Molecular probes for selective identification of protein aggregates are important to advance our understanding of the molecular pathogenesis underlying cerebral amyloidoses. Here we report the chemical design of pentameric thiophene derivatives, denoted luminescent conjugated oligothiophenes (LCOs), which could be used for real-time visualization of cerebral protein aggregates in transgenic mouse models of neurodegenerative diseases by multiphoton microscopy. One of the LCOs, p-FTAA, showed conformation-dependent optical properties and could be utilized for ex vivo spectral assignment of distinct prion deposits from two mouse-adapted prion strains. p-FTAA also revealed staining of transient soluble pre-fibrillar non-thioflavinophilic Aβ- assemblies during in vitro fibrillation of Aβ peptides. In brain tissue samples, Aβ deposits and neurofibrillary tangles (NFTs) were readily identified by a strong fluorescence from p-FTAA and the LCO staining showed complete co-localization with conventional antibodies (6E10 and AT8), indicating that p-FTAA detects all the immuno-positive aggregated proteinaceous species in Alzheimer disease, but with significantly shorter imaging time (100 fold) compared to immunofluorescence. In addition, a patchy islet-like staining of individual Aβ plaque was unveiled by the anti-oligomer A11 antibody during co-staining with p-FTAA, suggesting that pre-fibrillar species are likely an intrinsic component of Aβ plaques in human brain. The major hallmarks of Alzheimer’s disease, namely Aβ aggregates versus NFTs could also be distinguished due to distinct emission spectra from p-FTAA. Overall, we demonstrate that LCOs can be utilized as powerful practical research tools for studying protein aggregation diseases and facilitate the study of amyloid origin, evolution and maturation, Aβ−tau interactions and pathogenesis both ex vivo and in vivo. PMID:19624097

  14. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  15. A short term quality control tool for biodegradable microspheres.

    PubMed

    D'Souza, Susan; Faraj, Jabar A; Dorati, Rossella; DeLuca, Patrick P

    2014-06-01

    Accelerated in vitro release testing methodology has been developed as an indicator of product performance to be used as a discriminatory quality control (QC) technique for the release of clinical and commercial batches of biodegradable microspheres. While product performance of biodegradable microspheres can be verified by in vivo and/or in vitro experiments, such evaluation can be particularly challenging because of slow polymer degradation, resulting in extended study times, labor, and expense. Three batches of Leuprolide poly(lactic-co-glycolic acid) (PLGA) microspheres having varying morphology (process variants having different particle size and specific surface area) were manufactured by the solvent extraction/evaporation technique. Tests involving in vitro release, polymer degradation and hydration of the microspheres were performed on the three batches at 55°C. In vitro peptide release at 55°C was analyzed using a previously derived modification of the Weibull function termed the modified Weibull equation (MWE). Experimental observations and data analysis confirm excellent reproducibility studies within and between batches of the microsphere formulations demonstrating the predictability of the accelerated experiments at 55°C. The accelerated test method was also successfully able to distinguish the in vitro product performance between the three batches having varying morphology (process variants), indicating that it is a suitable QC tool to discriminate product or process variants in clinical or commercial batches of microspheres. Additionally, data analysis utilized the MWE to further quantify the differences obtained from the accelerated in vitro product performance test between process variants, thereby enhancing the discriminatory power of the accelerated methodology at 55°C. PMID:24519488

  16. A short term quality control tool for biodegradable microspheres.

    PubMed

    D'Souza, Susan; Faraj, Jabar A; Dorati, Rossella; DeLuca, Patrick P

    2014-06-01

    Accelerated in vitro release testing methodology has been developed as an indicator of product performance to be used as a discriminatory quality control (QC) technique for the release of clinical and commercial batches of biodegradable microspheres. While product performance of biodegradable microspheres can be verified by in vivo and/or in vitro experiments, such evaluation can be particularly challenging because of slow polymer degradation, resulting in extended study times, labor, and expense. Three batches of Leuprolide poly(lactic-co-glycolic acid) (PLGA) microspheres having varying morphology (process variants having different particle size and specific surface area) were manufactured by the solvent extraction/evaporation technique. Tests involving in vitro release, polymer degradation and hydration of the microspheres were performed on the three batches at 55°C. In vitro peptide release at 55°C was analyzed using a previously derived modification of the Weibull function termed the modified Weibull equation (MWE). Experimental observations and data analysis confirm excellent reproducibility studies within and between batches of the microsphere formulations demonstrating the predictability of the accelerated experiments at 55°C. The accelerated test method was also successfully able to distinguish the in vitro product performance between the three batches having varying morphology (process variants), indicating that it is a suitable QC tool to discriminate product or process variants in clinical or commercial batches of microspheres. Additionally, data analysis utilized the MWE to further quantify the differences obtained from the accelerated in vitro product performance test between process variants, thereby enhancing the discriminatory power of the accelerated methodology at 55°C.

  17. Core-double-shell Fe3O4@carbon@poly(In(III)-carboxylate) microspheres: cycloaddition of CO2 and epoxides on coordination polymer shells constituted by imidazolium-derived Al(III)-Salen bifunctional catalysts.

    PubMed

    An, Qiao; Li, Zifeng; Graff, Robert; Guo, Jia; Gao, Haifeng; Wang, Changchun

    2015-03-01

    A hydrid microsphere Fe3O4@carbon@poly(In(III)-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous In(III)-carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ∼5 nm of mesopore, 174.7 m(2)/g of surface area and 0.2175 cm(3)/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@In(III)-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field.

  18. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, William E.

    1984-01-01

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  19. Fabrication of glass microspheres with conducting surfaces

    DOEpatents

    Elsholz, W.E.

    1982-09-30

    A method for making hollow glass microspheres with conducting surfaces by adding a conducting vapor to a region of the glass fabrication furnace. As droplets or particles of glass forming material pass through multiple zones of different temperature in a glass fabrication furnace, and are transformed into hollow glass microspheres, the microspheres pass through a region of conducting vapor, forming a conducting coating on the surface of the microspheres.

  20. Mesenchymal stem cell-encapsulated collagen microspheres for bone tissue engineering.

    PubMed

    Chan, Barbara Pui; Hui, Ting Yan; Wong, Mei Yi; Yip, Kevin Hak Kong; Chan, Godfrey Chi Fung

    2010-04-01

    There is a demonstrated clinical need for alternatives of autologous fresh bone graft with excellent biological performance in osteoconductivity, osteoinductivity, and osteogenicity. We previously developed a collagen microencapsulation technology entrapping bone marrow-derived mesenchymal stem cells (MSCs) in a biomimetic collagen fiber meshwork and produced injectable collagen-MSC microspheres. In this study, we hypothesize that injectable microspheres with osteoconductivity, osteogenicity, and osteoinductivity can be fabricated by differentiating the encapsulated MSCs, from either human or mouse sources, toward osteogenic lineages in these three-dimensional microspheres. The osteogenicity, osteoconductivity, and osteoinductivity of the microspheres were evaluated in vitro. Osteogenic markers of the differentiating MSCs including alkaline phosphatase and calcium deposition showed positive staining. Osteoconductivity of the collagen meshwork in the microsphere was demonstrated by the presence of calcium phosphate deposits among the collagen fibers and by the significantly increased calcium content extracted from the microspheres. Moreover, osteoinductivity of the MSC-encapsulated microspheres was demonstrated by the ability to induce osteogenic differentiation of undifferentiated MSCs in both contact and noncontact coculture. This study contributes toward the future development of injectable alternatives for fresh bone grafts using autologous MSCs.

  1. Microspheres and their methods of preparation

    DOEpatents

    Bose, Anima B; Yang, Junbing

    2015-03-24

    Carbon microspheres are doped with boron to enhance the electrical and physical properties of the microspheres. The boron-doped carbon microspheres are formed by a CVD process in which a catalyst, carbon source and boron source are evaporated, heated and deposited onto an inert substrate.

  2. Novel ¹⁸F-labeled benzoxazole derivatives as potential positron emission tomography probes for imaging of cerebral β-amyloid plaques in Alzheimer's disease.

    PubMed

    Cui, Mengchao; Ono, Masahiro; Kimura, Hiroyuki; Ueda, Masashi; Nakamoto, Yuji; Togashi, Kaori; Okamoto, Yoko; Ihara, Masafumi; Takahashi, Ryosuke; Liu, Boli; Saji, Hideo

    2012-11-01

    Two radiofluoro-pegylated phenylbenzoxazole derivatives, 4-(5-(2-(2-(2-[(18)F]fluoroethoxy)ethoxy)ethoxy)benzo[d]oxazol-2-yl)-N-methylaniline ([(18)F]24) and 4-(5-(2-(2-(2-[(18)F]fluoroethoxy)ethoxy)ethoxy)benzo[d]oxazol-2-yl)-N,N-dimethylaniline ([(18)F]32), were synthesized and evaluated as probes for imaging cerebral β-amyloid (Aβ) plaques in living brain tissue by PET. [(18)F]24 and [(18)F]32 displayed high affinity for Aβ(1-42) aggregates (K(i) = 9.3 and 3.9 nM, respectively). In vitro autoradiography with sections of post-mortem AD brain and transgenic mouse brain confirmed the affinity of these tracers. Initial high uptake into and rapid washout from the brain in normal mice were observed. [(18)F]24 also displayed excellent binding to Aβ plaques in ex vivo autoradiographic experiments with Tg2576 mice. Furthermore, small-animal PET studies demonstrated significant differences in the clearance profile after the administration of [(18)F]24 between Tg2576 and wild-type mice. The results suggest [(18)F]24 to be a useful PET agent for detecting Aβ plaques in the living human brain.

  3. Multilayered polymer microspheres by thermal imprinting during microsphere growth.

    PubMed

    Takekoh, Ryu; Li, Wen-Hui; Burke, Nicholas A D; Stöver, Harald D H

    2006-01-11

    Modulation of the polymerization temperature in precipitation polymerizations was used to form onion-type polymer microspheres consisting of multiple nested layers. Specifically, the copolymerization of chloromethylstyrene and divinylbenzene-55 in acetonitrile, at temperatures ramping between 65 and 75 degrees C, led to monodisperse, cross-linked microspheres of about 10 mum diameter that have radial density profiles closely reflecting the thermal profiles used. This thermal imprinting is attributed to the copolymer formed being close to its theta point during the polymerization. As the microspheres grow by continuously capturing oligomers from solution, the resulting transient surface gel layer expands and contracts with temperature, and thus records the reaction temperature profile in the form of a corresponding density profile, even as it cross-links.

  4. Multilayered polymer microspheres by thermal imprinting during microsphere growth.

    PubMed

    Takekoh, Ryu; Li, Wen-Hui; Burke, Nicholas A D; Stöver, Harald D H

    2006-01-11

    Modulation of the polymerization temperature in precipitation polymerizations was used to form onion-type polymer microspheres consisting of multiple nested layers. Specifically, the copolymerization of chloromethylstyrene and divinylbenzene-55 in acetonitrile, at temperatures ramping between 65 and 75 degrees C, led to monodisperse, cross-linked microspheres of about 10 mum diameter that have radial density profiles closely reflecting the thermal profiles used. This thermal imprinting is attributed to the copolymer formed being close to its theta point during the polymerization. As the microspheres grow by continuously capturing oligomers from solution, the resulting transient surface gel layer expands and contracts with temperature, and thus records the reaction temperature profile in the form of a corresponding density profile, even as it cross-links. PMID:16390152

  5. Optical trapping of coated microspheres.

    PubMed

    Bormuth, Volker; Jannasch, Anita; Ander, Marcel; van Kats, Carlos M; van Blaaderen, Alfons; Howard, Jonathon; Schäffer, Erik

    2008-09-01

    In an optical trap, micron-sized dielectric particles are held by a tightly focused laser beam. The optical force on the particle is composed of an attractive gradient force and a destabilizing scattering force. We hypothesized that using anti-reflection-coated microspheres would reduce scattering and lead to stronger trapping. We found that homogeneous silica and polystyrene microspheres had a sharp maximum trap stiffness at a diameter of around 800 nm--the trapping laser wavelength in water--and that a silica coating on a polystyrene microsphere was a substantial improvement for larger diameters. In addition, we noticed that homogeneous spheres of a correct size demonstrated anti-reflective properties. Our results quantitatively agreed with Mie scattering calculations and serve as a proof of principle. We used a DNA stretching experiment to confirm the large linear range in detection and force of the coated microspheres and performed a high-force motor protein assay. These measurements show that the surfaces of the coated microspheres are compatible with biophysical assays.

  6. Advances in Microsphere Insulation Systems

    NASA Astrophysics Data System (ADS)

    Allen, M. S.; Baumgartner, R. G.; Fesmire, J. E.; Augustynowicz, S. D.

    2004-06-01

    Microsphere insulation, typically consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. Microspheres provide robust, low-maintenance insulation systems for cryogenic transfer lines and dewars. They also do not suffer from compaction problems typical of perlite that result in the necessity to reinsulate dewars because of degraded thermal performance and potential damage to its support system. Since microspheres are load bearing, autonomous insulation panels enveloped with lightweight vacuum-barrier materials can be created. Comprehensive testing performed at the Cryogenics Test Laboratory located at the NASA Kennedy Space Center demonstrated competitive thermal performance with other bulk materials. Test conditions were representative of actual-use conditions and included cold vacuum pressure ranging from high vacuum to no vacuum and compression loads from 0 to 20 psi. While microspheres have been recognized as a legitimate insulation material for decades, actual implementation has not been pursued. Innovative microsphere insulation system configurations and applications are evaluated.

  7. Improved Quantification of Cerebral Hemodynamics Using Individualized Time Thresholds for Assessment of Peak Enhancement Parameters Derived from Dynamic Susceptibility Contrast Enhanced Magnetic Resonance Imaging

    PubMed Central

    Nasel, Christian; Kalcher, Klaudius; Boubela, Roland; Moser, Ewald

    2014-01-01

    Purpose Assessment of cerebral ischemia often employs dynamic susceptibility contrast enhanced magnetic resonance imaging (DSC-MRI) with evaluation of various peak enhancement time parameters. All of these parameters use a single time threshold to judge the maximum tolerable peak enhancement delay that is supposed to reliably differentiate sufficient from critical perfusion. As the validity of this single threshold approach still remains unclear, in this study, (1) the definition of a threshold on an individual patient-basis, nevertheless (2) preserving the comparability of the data, was investigated. Methods The histogram of time-to-peak (TTP) values derived from DSC-MRI, the so-called TTP-distribution curve (TDC), was modeled using a double-Gaussian model in 61 patients without severe cerebrovascular disease. Particular model-based zf-scores were used to describe the arterial, parenchymal and venous bolus-transit phase as time intervals Ia,p,v. Their durations (delta Ia,p,v), were then considered as maximum TTP-delays of each phase. Results Mean-R2 for the model-fit was 0.967. Based on the generic zf-scores the proposed bolus transit phases could be differentiated. The Ip-interval reliably depicted the parenchymal bolus-transit phase with durations of 3.4 s–10.1 s (median = 4.3s), where an increase with age was noted (∼30 ms/year). Conclusion Individual threshold-adjustment seems rational since regular bolus-transit durations in brain parenchyma obtained from the TDC overlap considerably with recommended critical TTP-thresholds of 4 s–8 s. The parenchymal transit time derived from the proposed model may be utilized to individually correct TTP-thresholds, thereby potentially improving the detection of critical perfusion. PMID:25521121

  8. Simultaneous study of haemodynamic, metabolic and behavioural sequelae in a model of cerebral ischaemia in aged rats: effects of nicergoline.

    PubMed

    Le Poncin-Lafitte, M; Grosdemouge, C; Duterte, D; Rapin, J R

    1984-01-01

    Unilateral cerebral ischaemia was induced in 18-month-old Long-Evans rats by injection of 2,000 labelled microspheres (phi 50 microns) into the carotid blood stream. This results in an ipsilateral decrease in cerebral blood flow, development of severe oedema and modifications of glucose uptake and consumption. Furthermore, this ischaemia led to a deterioration of the avoidance response in conditioned animals. All these disturbances, including the cerebral oedema, diminished with nicergoline pretreatment. PMID:6706123

  9. Polarization Dependent Whispering Gallery Modes in Microspheres

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)

    2016-01-01

    A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.

  10. Sustained-release microsphere formulation containing an agrochemical by polyurethane polymerization during an agitation granulation process.

    PubMed

    Terada, Takatoshi; Tagami, Manabu; Ohtsubo, Toshiro; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2016-07-25

    In this report, a new solventless microencapsulation method by synthesizing polyurethane (PU) from polyol and isocyanate during an agglomeration process in a high-speed mixing apparatus was developed. Clothianidin (CTD), which is a neonicotinoid insecticide and highly effective against a wide variety of insect pests, was used as the model compound. The microencapsulated samples covered with PU (CTD microspheres) had a median diameter of <75μm and sustained-release properties. The CTD microspheres were analyzed by synchrotron X-ray computed tomography measurements. Multiple cores of CTD and other solid excipient were dispersed in PU. Although voids appeared in the CTD microspheres after CTD release, the spherical shape of the microspheres remained stable and no change in its framework was observed. The experimental release data were highly consistent with the Baker-Lonsdale model derived from drug release of spherical monolithic dispersions and consistent with the computed tomography measurements. PMID:27246815

  11. Microstructured microspheres of hydroxyapatite bioceramic.

    PubMed

    Sunny, M C; Ramesh, P; Varma, H K

    2002-07-01

    Hydroxyapatite (HAP) particles having spherical geometry and 125-1000 microm in size range were prepared using a solid-in-water-in-oil (S/W/O) emulsion, cross-linking technique. An aqueous solution of chitosan containing different loading of HAP was dispersed as droplet in liquid paraffin using a stabilizing agent. Cross-linking of chitosan was induced by adding appropriate amount of glutaraldehyde saturated toluene. Chitosan microspheres containing HAP were sintered at 1150 degrees C to obtain pure HAP microspheres. The spheres thus produced were examined by scanning electron microscopy. The percentage yield and size distributions of the spheres were also determined.

  12. Production of monodisperse, polymeric microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Rhim, Won-Kyu (Inventor); Hyson, Michael T. (Inventor); Chang, Manchium (Inventor)

    1990-01-01

    Very small, individual polymeric microspheres with very precise size and a wide variation in monomer type and properties are produced by deploying a precisely formed liquid monomer droplet, suitably an acrylic compound such as hydroxyethyl methacrylate into a containerless environment. The droplet which assumes a spheroid shape is subjected to polymerizing radiation such as ultraviolet or gamma radiation as it travels through the environment. Polymeric microspheres having precise diameters varying no more than plus or minus 5 percent from an average size are recovered. Many types of fillers including magnetic fillers may be dispersed in the liquid droplet.

  13. Cerebral palsy.

    PubMed

    Wimalasundera, Neil; Stevenson, Valerie L

    2016-06-01

    Cerebral palsy has always been known as a disorder of movement and posture resulting from a non-progressive injury to the developing brain; however, more recent definitions allow clinicians to appreciate more than just the movement disorder. Accurate classification of cerebral palsy into distribution, motor type and functional level has advanced research. It also facilitates appropriate targeting of interventions to functional level and more accurate prognosis prediction. The prevalence of cerebral palsy remains fairly static at 2-3 per 1000 live births but there have been some changes in trends for specific causal groups. Interventions for cerebral palsy have historically been medical and physically focused, often with limited evidence to support their efficacy. The use of more appropriate outcome measures encompassing quality of life and participation is helping to deliver treatments which are more meaningful for people with cerebral palsy and their carers.

  14. Hypothermia reduces cerebral metabolic rate and cerebral blood flow in newborn pigs

    SciTech Connect

    Busija, D.W.; Leffler, C.W. )

    1987-10-01

    The authors examined effects of hypothermia on cerebral metabolic rate and cerebral blood flow in anesthetized, newborn pigs (1-4 days old). Cerebral blood flow (CBF) was determined with 15-{mu}m radioactive microspheres. Regional CBF ranged from 44 to 66 ml{center dot}min{sup {minus}1}{center dot}100 g{sup {minus}1}, and cerebral metabolic rate was 1.94 {plus minus} 0.23 ml O{sub 2}{center dot}100 g{sup {minus}1}{center dot}min{sup {minus}1} during normothermia (39{degree}C). Reduction of rectal temperature to 34-35{degree}C decreased CBF and cerebral metabolic rate 40-50%. In another group of piglets, they examined responsiveness of the cerebral circulation to arterial hypercapnia during hypothermia. Although absolute values for normocapnic and hypercapnic CBF were reduced by hypothermia and absolute values for normocapnic and hypercapnic cerebrovascular resistance were increased, the percentage changes from control in these variables during hypercapnia were similar during normothermia and hypothermia. In another group of animals that were maintained normothermic and exposed to two episodes of hypercapnia, there was no attenuation of cerebrovascular dilation during the second episode. They conclude that hypothermia reduces CBF secondarily to a decrease in cerebral metabolic rate and that percent dilator responsiveness to arterial hypercapnia is unaltered when body temperature is reduced.

  15. Cerebral palsy.

    PubMed

    Graham, H Kerr; Rosenbaum, Peter; Paneth, Nigel; Dan, Bernard; Lin, Jean-Pierre; Damiano, Diane L; Becher, Jules G; Gaebler-Spira, Deborah; Colver, Allan; Reddihough, Dinah S; Crompton, Kylie E; Lieber, Richard L

    2016-01-07

    Cerebral palsy is the most common cause of childhood-onset, lifelong physical disability in most countries, affecting about 1 in 500 neonates with an estimated prevalence of 17 million people worldwide. Cerebral palsy is not a disease entity in the traditional sense but a clinical description of children who share features of a non-progressive brain injury or lesion acquired during the antenatal, perinatal or early postnatal period. The clinical manifestations of cerebral palsy vary greatly in the type of movement disorder, the degree of functional ability and limitation and the affected parts of the body. There is currently no cure, but progress is being made in both the prevention and the amelioration of the brain injury. For example, administration of magnesium sulfate during premature labour and cooling of high-risk infants can reduce the rate and severity of cerebral palsy. Although the disorder affects individuals throughout their lifetime, most cerebral palsy research efforts and management strategies currently focus on the needs of children. Clinical management of children with cerebral palsy is directed towards maximizing function and participation in activities and minimizing the effects of the factors that can make the condition worse, such as epilepsy, feeding challenges, hip dislocation and scoliosis. These management strategies include enhancing neurological function during early development; managing medical co-morbidities, weakness and hypertonia; using rehabilitation technologies to enhance motor function; and preventing secondary musculoskeletal problems. Meeting the needs of people with cerebral palsy in resource-poor settings is particularly challenging.

  16. Cerebral palsy.

    PubMed

    Graham, H Kerr; Rosenbaum, Peter; Paneth, Nigel; Dan, Bernard; Lin, Jean-Pierre; Damiano, Diane L; Becher, Jules G; Gaebler-Spira, Deborah; Colver, Allan; Reddihough, Dinah S; Crompton, Kylie E; Lieber, Richard L

    2016-01-01

    Cerebral palsy is the most common cause of childhood-onset, lifelong physical disability in most countries, affecting about 1 in 500 neonates with an estimated prevalence of 17 million people worldwide. Cerebral palsy is not a disease entity in the traditional sense but a clinical description of children who share features of a non-progressive brain injury or lesion acquired during the antenatal, perinatal or early postnatal period. The clinical manifestations of cerebral palsy vary greatly in the type of movement disorder, the degree of functional ability and limitation and the affected parts of the body. There is currently no cure, but progress is being made in both the prevention and the amelioration of the brain injury. For example, administration of magnesium sulfate during premature labour and cooling of high-risk infants can reduce the rate and severity of cerebral palsy. Although the disorder affects individuals throughout their lifetime, most cerebral palsy research efforts and management strategies currently focus on the needs of children. Clinical management of children with cerebral palsy is directed towards maximizing function and participation in activities and minimizing the effects of the factors that can make the condition worse, such as epilepsy, feeding challenges, hip dislocation and scoliosis. These management strategies include enhancing neurological function during early development; managing medical co-morbidities, weakness and hypertonia; using rehabilitation technologies to enhance motor function; and preventing secondary musculoskeletal problems. Meeting the needs of people with cerebral palsy in resource-poor settings is particularly challenging. PMID:27188686

  17. Development of Risperidone PLGA Microspheres

    PubMed Central

    D'Souza, Susan; Faraj, Jabar A.; Giovagnoli, Stefano; DeLuca, Patrick P.

    2014-01-01

    The aim of this study was to design and evaluate biodegradable PLGA microspheres for sustained delivery of Risperidone, with an eventual goal of avoiding combination therapy for the treatment of schizophrenia. Two PLGA copolymers (50 : 50 and 75 : 25) were used to prepare four microsphere formulations of Risperidone. The microspheres were characterized by several in vitro techniques. In vivo studies in male Sprague-Dawley rats at 20 and 40 mg/kg doses revealed that all formulations exhibited an initial burst followed by sustained release of the active moiety. Additionally, formulations prepared with 50 : 50 PLGA had a shorter duration of action and lower cumulative AUC levels than the 75 : 25 PLGA microspheres. A simulation of multiple dosing at weekly or 15-day regimen revealed pulsatile behavior for all formulations with steady state being achieved by the second dose. Overall, the clinical use of Formulations A, B, C, or D will eliminate the need for combination oral therapy and reduce time to achieve steady state, with a smaller washout period upon cessation of therapy. Results of this study prove the suitability of using PLGA copolymers of varying composition and molecular weight to develop sustained release formulations that can tailor in vivo behavior and enhance pharmacological effectiveness of the drug. PMID:24616812

  18. Microspheres and nanoparticles from ultrasound

    NASA Astrophysics Data System (ADS)

    Suh, Won Hyuk

    Improved preparations of various examples of monodispersed, porous, hollow, and core-shell metal and semiconductor nanoparticles or nanowires have been developed. Now titania microspheres and nanoparticles and silica microspheres can be synthesized using an inexpensive high frequency (1.7 MHz) ultrasonic generator (household humidifier; ultrasonic spray pyrolysis; USP). Morphology and pore size of titania microspheres were controlled by the silica to Ti(IV) ratio and silica particle size. Fine tuning the precursor ratio affords sub-50 nm titania nanoparticles as well. In terms of silica microspheres, morphology was controlled by the silica to organic monomer ratio. In liquids irradiated with high intensity ultrasound (20 kHz; HIUS), acoustic cavitation produces high energy chemistry through intense local heating inside the gas phase of collapsing bubbles in the liquid. HIUS and USP confine the chemical reactions to isolated sub-micron reaction zones, but sonochemistry does so in a heated gas phase within a liquid, while USP uses a hot liquid droplet carried by a gas flow. Thus, USP can be viewed as a method of phase-separated synthesis using submicron-sized droplets as isolated chemical reactors for nanomaterial synthesis. While USP has been used to create both titania and silica spheres separately, there are no prior reports of titania-silica composites. Such nanocomposites of metal oxides have been produced, and by further manipulation, various porous structures with fascinating morphologies were generated. Briefly, a precursor solution was nebulized using a commercially available household ultrasonic humidifier (1.7 MHz ultrasound generator), and the resulting mist was carried in a gas stream of air through a quartz glass tube in a hot furnace. After exiting the hot zone, these microspheres are porous or hollow and in certain cases magnetically responsive. In the case of titania microspheres, they are rapidly taken up into the cytoplasm of mammalian cells and

  19. Cerebral blood flow with [15O]water PET studies using an image-derived input function and MR-defined carotid centerlines

    NASA Astrophysics Data System (ADS)

    Fung, Edward K.; Carson, Richard E.

    2013-03-01

    Full quantitative analysis of brain PET data requires knowledge of the arterial input function into the brain. Such data are normally acquired by arterial sampling with corrections for delay and dispersion to account for the distant sampling site. Several attempts have been made to extract an image-derived input function (IDIF) directly from the internal carotid arteries that supply the brain and are often visible in brain PET images. We have devised a method of delineating the internal carotids in co-registered magnetic resonance (MR) images using the level-set method and applying the segmentations to PET images using a novel centerline approach. Centerlines of the segmented carotids were modeled as cubic splines and re-registered in PET images summed over the early portion of the scan. Using information from the anatomical center of the vessel should minimize partial volume and spillover effects. Centerline time-activity curves were taken as the mean of the values for points along the centerline interpolated from neighboring voxels. A scale factor correction was derived from calculation of cerebral blood flow (CBF) using gold standard arterial blood measurements. We have applied the method to human subject data from multiple injections of [15O]water on the HRRT. The method was assessed by calculating the area under the curve (AUC) of the IDIF and the CBF, and comparing these to values computed using the gold standard arterial input curve. The average ratio of IDIF to arterial AUC (apparent recovery coefficient: aRC) across 9 subjects with multiple (n = 69) injections was 0.49 ± 0.09 at 0-30 s post tracer arrival, 0.45 ± 0.09 at 30-60 s, and 0.46 ± 0.09 at 60-90 s. Gray and white matter CBF values were 61.4 ± 11.0 and 15.6 ± 3.0 mL/min/100 g tissue using sampled blood data. Using IDIF centerlines scaled by the average aRC over each subjects’ injections, gray and white matter CBF values were 61.3 ± 13.5 and 15.5 ± 3.4 mL/min/100 g tissue. Using global

  20. Optically active microspheres constructed by helical substituted polyacetylene and used for adsorption of organic compounds in aqueous systems.

    PubMed

    Liang, Junya; Song, Ci; Deng, Jianping

    2014-11-12

    This article reports optically active microspheres consisting of chiral helical substituted polyacetylene and β-cyclodextrin-derivative (β-CD-A). The microspheres showed remarkable adsorption toward various organic compounds in water. To prepare the microspheres, an acetylenic-derived helical macro-monomer was synthesized and then underwent aqueous suspension copolymerization with octadecyl acrylate and butyl acrylate by using azobis(isobutyronitrile) as initiator and β-CD-A simultaneously as comonomer and cross-linking agent. The helical macro-monomer chains enabled the microspheres to exhibit desirable enantio-differentiating adsorption capacity toward chiral compounds respectively dissolved in organic solvent, dispersed in water, and dissolved in water. The saturated absorbency toward (R)-(+)- and (S)-(-)-1-phenylethylamine was 29 and 12 mg · g(-1), respectively. The microspheres also showed large oil absorbency (e.g., 22 g · g(-1) CCl4) and a large adsorption toward methyl red (as a model for organic dyes) dispersed in water. The presence of β-CD-A moieties improved the adsorption performance of the microspheres. The present optically active microspheres open a new approach for preparing adsorbents particularly chiral adsorbents with potentials for wastewater treatment. PMID:25290256

  1. Cerebral palsy

    MedlinePlus

    ... with pain and spasticity Place feeding tubes Release joint contractures ... the hip joint Injuries from falls Pressure sores Joint ... of the people who are affected by cerebral palsy) Social stigma

  2. Cerebral Palsy

    MedlinePlus

    ... Español (Spanish) Recommend on Facebook Tweet Share Compartir Cerebral palsy (CP) is a group of disorders that affect a ... ability to move and maintain balance and posture. CP is the most common motor disability in childhood. ...

  3. Cerebral Arteriosclerosis

    MedlinePlus

    ... Cerebral arteriosclerosis is the result of thickening and hardening of the walls of the arteries in the ... cause an ischemic stroke. When the thickening and hardening is uneven, arterial walls can develop bulges (called ...

  4. Cerebral hypoxia

    MedlinePlus

    ... death. Treatment depends on the cause of the hypoxia. Basic life support is most important. Treatment involves: Breathing ... Complications of cerebral hypoxia include a prolonged vegetative ... sleep-wake cycle, and eye opening, but the person is not alert ...

  5. Cerebral Paragonimiasis.

    PubMed

    Miyazaki, I

    1975-01-01

    The first case of cerebral paragonimiasis was reported by Otani in Japan in 1887. This was nine years after Kerbert's discovery of the fluke in the lungs of Bengal tigers and seven years after a human pulmonary infection by the fluke was demonstrated by Baelz and Manson. The first case was a 26-year-old man who had been suffering from cough and hemosputum for one year. The patient developed convulsive seizures with subsequent coma and died. The postmortem examination showed cystic lesions in the right frontal and occipital lobes. An adult fluke was found in the occipital lesion and another was seen in a gross specimen of normal brain tissue around the affected occipital lobe. Two years after Otani's discovery, at autopsy a 29-year-old man with a history of Jacksonian seizure was reported as having cerebral paragonimiasis. Some time later, however, it was confirmed that the case was actually cerebral schistosomiasis japonica. Subsequently, cases of cerebral paragonimiasis were reported. However, the majority of these cases were not confirmed histologically. It was pointed out that some of these early cases were probably not Paragonimus infection. After World War II, reviews as well as case reports were published. Recently, investigations have been reported from Korea, with a clinicla study on 62 cases of cerebral paragonimiasis seen at the Neurology Department of the National Medical Center, Seoul, between 1958 and 1964. In 1971 Higashi described a statistical study on 105 cases of cerebral paragonimiasis that had been treated surgically in Japan.

  6. Cerebral Paragonimiasis.

    PubMed

    Miyazaki, I

    1975-01-01

    The first case of cerebral paragonimiasis was reported by Otani in Japan in 1887. This was nine years after Kerbert's discovery of the fluke in the lungs of Bengal tigers and seven years after a human pulmonary infection by the fluke was demonstrated by Baelz and Manson. The first case was a 26-year-old man who had been suffering from cough and hemosputum for one year. The patient developed convulsive seizures with subsequent coma and died. The postmortem examination showed cystic lesions in the right frontal and occipital lobes. An adult fluke was found in the occipital lesion and another was seen in a gross specimen of normal brain tissue around the affected occipital lobe. Two years after Otani's discovery, at autopsy a 29-year-old man with a history of Jacksonian seizure was reported as having cerebral paragonimiasis. Some time later, however, it was confirmed that the case was actually cerebral schistosomiasis japonica. Subsequently, cases of cerebral paragonimiasis were reported. However, the majority of these cases were not confirmed histologically. It was pointed out that some of these early cases were probably not Paragonimus infection. After World War II, reviews as well as case reports were published. Recently, investigations have been reported from Korea, with a clinicla study on 62 cases of cerebral paragonimiasis seen at the Neurology Department of the National Medical Center, Seoul, between 1958 and 1964. In 1971 Higashi described a statistical study on 105 cases of cerebral paragonimiasis that had been treated surgically in Japan. PMID:1095292

  7. Self-Assembly of pH-Responsive Microspheres for Intestinal Delivery of Diverse Lipophilic Therapeutics.

    PubMed

    Zhou, Xing; Zhao, Yang; Chen, Siyu; Han, Songling; Xu, Xiaoqiu; Guo, Jiawei; Liu, Mengyu; Che, Ling; Li, Xiaohui; Zhang, Jianxiang

    2016-08-01

    Targeted delivery of therapeutics to the intestine is preferred for the management of many diseases due to its diverse advantages. Currently, there are still challenges in creating cost-effective and translational pH-responsive microspheres for intestinal delivery of various hydrophobic drugs. Herein we report a multiple noncovalent interactions-mediated assembly strategy in which carboxyl-bearing compounds (CBCs) are guest molecules, while poly(N-isopropylacrylamide) (PNIPAm) serves as a host polymer. Formation of microparticles and therapeutic packaging can be achieved simultaneously by this assembly approach, leading to well-shaped microspheres with extremely higher drug loading capacity as compared to microspheres based on two FDA-approved materials of poly(d,l-lactide-co-glycolide) (PLGA) and an enteric coating polymer EudragitS 100 (S100). Also, carboxyl-deficient hydrophobic drugs can be effectively entrapped. These assembled microspheres, with excellent reconstitution capability as well as desirable scalability, could selectively release drug molecules under intestinal conditions. By significantly enhancing drug dissolution/release in the intestine, these pH-responsive assemblies may notably improve the oral bioavailability of loaded therapeutics. Moreover, the assembled microspheres possessed superior therapeutic performance in rodent models of inflammation and tumor over the control microspheres derived from PLGA and S100. Therapy with newly developed microspheres did not cause undesirable side effects. Furthermore, in vivo evaluation in mice revealed the carrier material PNIPAm was safe for oral delivery at doses as high as 10 g/kg. Collectively, our findings demonstrated that this type of pH-responsive microsphere may function as superior and translational intestine-directed delivery systems for a diverse array of therapeutics. PMID:27398635

  8. Filling Porous Microspheres With Magnetic Material

    NASA Technical Reports Server (NTRS)

    Chang, Manchium; Colvin, Michael S.

    1990-01-01

    New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

  9. Microsphere coated substrate containing reactive aldehyde groups

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Richard C. K. (Inventor)

    1984-01-01

    A synthetic organic resin is coated with a continuous layer of contiguous, tangential, individual microspheres having a uniform diameter preferably between 100 Angstroms and 2000 Angstroms. The microspheres are an addition polymerized polymer of an unsaturated aldehyde containing 4 to 20 carbon atoms and are covalently bonded to the substrate by means of high energy radiation grafting. The microspheres contain reactive aldehyde groups and can form conjugates with proteins such as enzymes or other aldehyde reactive materials.

  10. Cerebral Microcirculation during Experimental Normovolaemic Anemia

    PubMed Central

    Bellapart, Judith; Cuthbertson, Kylie; Dunster, Kimble; Diab, Sara; Platts, David G.; Raffel, O. Christopher; Gabrielian, Levon; Barnett, Adrian; Paratz, Jenifer; Boots, Rob; Fraser, John F.

    2016-01-01

    Anemia is accepted among critically ill patients as an alternative to elective blood transfusion. This practice has been extrapolated to head injury patients with only one study comparing the effects of mild anemia on neurological outcome. There are no studies quantifying microcirculation during anemia. Experimental studies suggest that anemia leads to cerebral hypoxia and increased rates of infarction, but the lack of clinical equipoise, when testing the cerebral effects of transfusion among critically injured patients, supports the need of experimental studies. The aim of this study was to quantify cerebral microcirculation and the potential presence of axonal damage in an experimental model exposed to normovolaemic anemia, with the intention of describing possible limitations within management practices in critically ill patients. Under non-recovered anesthesia, six Merino sheep were instrumented using an intracardiac transeptal catheter to inject coded microspheres into the left atrium to ensure systemic and non-chaotic distribution. Cytometric analyses quantified cerebral microcirculation at specific regions of the brain. Amyloid precursor protein staining was used as an indicator of axonal damage. Animals were exposed to normovolaemic anemia by blood extractions from the indwelling arterial catheter with simultaneous fluid replacement through a venous central catheter. Simultaneous data recording from cerebral tissue oxygenation, intracranial pressure, and cardiac output was monitored. A regression model was used to examine the effects of anemia on microcirculation with a mixed model to control for repeated measures. Homogeneous and normal cerebral microcirculation with no evidence of axonal damage was present in all cerebral regions, with no temporal variability, concluding that acute normovolaemic anemia does not result in short-term effects on cerebral microcirculation in the ovine brain. PMID:26869986

  11. Glass microspheres for medical applications

    NASA Astrophysics Data System (ADS)

    Conzone, Samuel David

    Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in <1 week, without causing any detectable joint damage. The combination of dysprosium lithium borate glass microspheres and EDTA chelation therapy provides an unique "tool" for the medical community, which can deliver a large dose (>100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass

  12. Cerebral Palsy (For Parents)

    MedlinePlus

    ... Story" 5 Things to Know About Zika & Pregnancy Cerebral Palsy KidsHealth > For Parents > Cerebral Palsy Print A A ... kids who are living with the condition. About Cerebral Palsy Cerebral palsy is one of the most common ...

  13. Cerebral palsy - resources

    MedlinePlus

    Resources - cerebral palsy ... The following organizations are good resources for information on cerebral palsy : National Institute of Neurological Disorders and Stroke -- www.ninds.nih.gov/disorders/cerebral_palsy/cerebral_palsy. ...

  14. Coupling system to a microsphere cavity

    NASA Technical Reports Server (NTRS)

    Iltchenko, Vladimir (Inventor); Maleki, Lute (Inventor); Yao, Steve (Inventor); Wu, Chi (Inventor)

    2002-01-01

    A system of coupling optical energy in a waveguide mode, into a resonator that operates in a whispering gallery mode. A first part of the operation uses a fiber in its waveguide mode to couple information into a resonator e.g. a microsphere. The fiber is cleaved at an angle .PHI. which causes total internal reflection within the fiber. The energy in the fiber then forms an evanescent field and a microsphere is placed in the area of the evanescent field. If the microsphere resonance is resonant with energy in the fiber, then the information in the fiber is effectively transferred to the microsphere.

  15. Cerebral autoregulation with changes in arterial and cerebral venous pressure

    SciTech Connect

    McPherson, R.W.; Traystman, R.J.

    1986-03-01

    The effect of cerebral venous pressure (Pcv) elevation on cerebral autoregulation has been incompletely studied. The authors compared the effect of decreased cerebral perfusion pressure (CPP) by elevated Pcv and decreased arterial pressure (Pa) on cerebral blood flow (CBF) in a canine modified bypass model. CPP of 80, 70, 60, 50, 40 and 30 mmHg were produced by decreasing Pa with intracranial pressure (ICP) and Pcv maintained at 0 mmHg (group 1, n = 5), or by elevating Pcv as Pa was maintained at 80 mmHg (group 2, n = 5. CBF was measured using radiolabeled microspheres, and CMRO/sub 2/ = CBF times arterial-sagittal sinus O/sub 2/ content difference. Cerebrovascular resistance (CVR) = CPP/CBF. In group 1 CBF (ml/100 gm/min) was unchanged from control (36 +/- 4) as CPP was decreased from 80 to 40 mmHg. As CPP was decreased to 30 mmHg, CBF decreased to 28 +/- 1. CVR (mmHg/ml/min/100 gm) was 2.3 +/- 0.3 and progressively decreased to 1.0 +/- 0.1 at CPP of 30 mmHg. In group 2 CBF was 34 +/- 3 and was unchanged as CPP decreased to 50 mmHg. At CPP of 40 and 30 mmHg CBF decreased to 25 +/- 3 and 22 +/- 2 respectively. Control CRV was 2.4 +/- 0.2 and progressively decreased to 1.4 +/- 0.1 as CPP decreased to 30 mmHg. CMRO/sub 2/ was unchanged from control in both groups. Thus, CBF is maintained to low CPP regardless of whether vascular transmural pressure was decreased (decrease Pa) or increased (increased Pcv) demonstrating that the myogenic mechanism of autoregulation may be unimportant in normoxic dogs.

  16. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, Richard W.; Hrubesh, Lawrence W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

  17. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, R.W.; Hrubesh, L.W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

  18. Effects of naftidrofuryl oxalate on microsphere embolism-induced decrease in regional blood flow of rat brain.

    PubMed Central

    Miyake, K.; Takagi, N.; Takeo, S.

    1994-01-01

    1. The purpose of the present study was to determine whether naftidrofuryl oxalate (naftidrofuryl), a vasodilator, is capable of improving brain regional blood flow of animals in sustained ischaemia. 2. Cerebral ischaemia was induced by injecting 900 microspheres (48 microns in diameter) into the right internal carotid artery of rats. Cerebral blood flow of brain regions was measured by a hydrogen clearance method on the 3rd, 7th and 28th days after the onset of ischaemia. Ischaemic animals were treated with naftidrofuryl, 15 mg kg-1 day-1 i.p., from the first to 28th day. 3. Microsphere-embolism caused a sustained decrease in cortical and striatal blood flow over a period of 28 days, whereas hippocampal blood flow was decreased on the 3rd day but not on the 7th or 28th day. On the 3rd day, the striatal and hippocampal but not cortical blood flow of naftidrofuryl-treated, microsphere-embolized rats was higher than untreated rats. On the 7th and 28th days, the cortical and striatal blood flow of the treated and untreated animals did not differ. 4. Brain slices from microsphere-embolized rats contained areas, which were not stained with triphenyltetrazolium chloride (TTC), to a similar degree on the 3rd, 7th and 28th days, indicating the genesis of cerebral infarction. TTC-unstained areas of microsphere-embolized rats that had received naftidrofuryl treatment were smaller than those of untreated rats on the 3rd and 7th days, but not on the 28th day.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8032646

  19. Nonaggregating Microspheres Containing Aldehyde Groups

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan

    1989-01-01

    Cobalt gamma irradiation of hydrophilic monomers in presence of acrolein yields exceptionally-stable, nonaggregating microspheres. Mixtures of 2-hydroxyethyl methacrylate (HEMA) and acrolein form homogeneous solutions in distilled water containing 0.4 percent polyethylene oxide (PEO). After deaeration with nitrogen, mixtures irradiated at room temperature with gamma rays from cobalt source; total exposure time 4 hours, at rate of 0.2 milliroentgen per hour. Reaction product centrifuged three times for purification and kept in distilled water.

  20. Microspheres in Plasma Display Panels

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Filling small bubbles of molten glass with gases is just as difficult as it sounds, but the technical staff at NASA is not known to shy away from a difficult task. When Microsphere Systems, Inc. (MSI), of Ypsilanti, Michigan, and Imaging Systems Technology, Inc. (IST), of Toledo, Ohio, were trying to push the limits of plasma displays but were having difficulty with the designs, NASA s Glenn Garrett Morgan Commercialization Initiative (GMCI) assembled key personnel at Glenn Research Center and Ohio State University for a brainstorming session to come up with a solution for the companies. They needed a system that could produce hollow, glass micro-sized spheres (microspheres) that could be filled with a variety of gasses. But the extremely high temperature required to force the micro-sized glass bubbles to form at the tip of a metal nozzle resulted in severe discoloration of the microspheres. After countless experiments on various glass-metal combinations, they had turned to the GMCI for help. NASA experts in advanced metals, ceramics, and glass concluded that a new design approach was necessary. The team determined that what was needed was a phosphate glass composition that would remain transparent, and they went to work on a solution. Six weeks later, using the design tips from the NASA team, Tim Henderson, president of MSI, had designed a new system in which all surfaces in contact with the molten glass would be ceramic instead of metal. Meanwhile, IST was able to complete a Phase I Small Business Innovation Research (SBIR) grant supported by the National Science Foundation (NSF) and supply a potential customer with samples of the microspheres for evaluation as filler materials for high-performance insulations.

  1. Cerebral palsy.

    PubMed

    Colver, Allan; Fairhurst, Charles; Pharoah, Peter O D

    2014-04-01

    The syndrome of cerebral palsy encompasses a large group of childhood movement and posture disorders. Severity, patterns of motor involvement, and associated impairments such as those of communication, intellectual ability, and epilepsy vary widely. Overall prevalence has remained stable in the past 40 years at 2-3·5 cases per 1000 livebirths, despite changes in antenatal and perinatal care. The few studies available from developing countries suggest prevalence of comparable magnitude. Cerebral palsy is a lifelong disorder; approaches to intervention, whether at an individual or environmental level, should recognise that quality of life and social participation throughout life are what individuals with cerebral palsy seek, not improved physical function for its own sake. In the past few years, the cerebral palsy community has learned that the evidence of benefit for the numerous drugs, surgery, and therapies used over previous decades is weak. Improved understanding of the role of multiple gestation in pathogenesis, of gene environment interaction, and how to influence brain plasticity could yield significant advances in treatment of the disorder. Reduction in the prevalence of post-neonatal cerebral palsy, especially in developing countries, should be possible through improved nutrition, infection control, and accident prevention.

  2. Polymethyl methacrylate microspheres in collagen.

    PubMed

    Haneke, Eckart

    2004-12-01

    Artecoll was developed about 20 years ago and underwent a number of production changes until it recently became FDA approved under the new name of Artefill. This product contains 20% polymethyl methacrylate (PMMA) microspheres with a diameter of 30 to 40 microm, which are suspended in a 3.5% atelo-collagen solution. The PMMA microspheres are now purified and no longer have an electrostatic charge, which in part was the cause for the early granulomatous reactions. Further, PMMA has long been known as bone cement and has been used in cosmetic surgery with a very good safety record. PMMA microspheres are biologically inert and nondegradable. The treatment results are therefore permanent and technical errors as well as incorrect injections will last. Due to the early record of granuloma formation, there is still a debate as to whether this product-as well as all other permanent fillers-should be injected for cosmetic reasons or not. With proper indications, excellent injection techniques, and realistic expectations as to what can be expected, this product has now proved to be one of the superior permanent filler substances.

  3. Protective colloids and polylactic acid co-affecting the polymorphic crystal forms and crystallinity of indomethacin encapsulated in microspheres.

    PubMed

    Lin, S Y; Chen, K S; Teng, H H

    1999-01-01

    The co-effect of protective colloids and polylactic acid (PLA) on the polymorphic crystal forms and crystallinity of indomethacin (IMC) in IMC-loaded PLA microspheres was investigated with differential scanning calorimetry, infrared spectroscopy and x-ray diffractometry, to evaluate the polymorphic crystal forms and crystallinity of IMC encapsulated in PLA microspheres. The surfactant, sodium dodecyl sulphate (SDS), was also used as a dispersing agent. The results indicate that the polymorphism and crystallinity of IMC encapsulated in IMC-loaded PLA microspheres was dependent on the type of protective colloid and PLA used. The amorphous state and alpha-form of IMC were found in the IMC-loaded PLA microspheres prepared using polysaccharide (pectin or beta-cyclodextrin) as a protective colloid or SDS as a dispersing agent. However, the amorphous and methylene chloride solvate of IMC seemed to exist in the IMC-loaded PLA microspheres prepared with the proteins (gelatin or albumin), synthetic cellulose derivative (methyl cellulose or hydroxylpropyl methylcellulose) or the synthetic nonionic polymer (polyvinyl alcohol, polyvinyl pyrrolidone or biosoluble polymer) as a protective colloid. PLA was found to express a certain crystallinity in microspheres and not be affected by the protective colloids, but it played a more important role in influencing the crystallization of IMC during microencapsulation than the protective colloids. No interaction occurred in the physical mixture of IMC and PLA, nor in the IMC-loaded PLA microspheres.

  4. Optical microdiscus resonators by flattening microspheres

    NASA Astrophysics Data System (ADS)

    Senthil Murugan, Ganapathy; Wilkinson, James S.; Zervas, Michalis N.

    2012-08-01

    A "soften-and-squash" fabrication technique has been demonstrated to controllably deform optical microspheres and form microdiscus resonators with improved surface quality. The characteristic shape of the microdiscus results in superior mode control, and the annealing involved in the fabrication process leads to quality factors (Q) exceeding 105, which is about two orders of magnitude higher than the initial microspheres.

  5. POROUS WALL, HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Sexton, W.

    2012-06-30

    Hollow Glass Microspheres (HGM) is not a new technology. All one has to do is go to the internet and Google{trademark} HGM. Anyone can buy HGM and they have a wide variety of uses. HGM are usually between 1 to 100 microns in diameter, although their size can range from 100 nanometers to 5 millimeters in diameter. HGM are used as lightweight filler in composite materials such as syntactic foam and lightweight concrete. In 1968 a patent was issued to W. Beck of the 3M{trademark} Company for 'Glass Bubbles Prepared by Reheating Solid Glass Particles'. In 1983 P. Howell was issued a patent for 'Glass Bubbles of Increased Collapse Strength' and in 1988 H. Marshall was issued a patent for 'Glass Microbubbles'. Now Google{trademark}, Porous Wall, Hollow Glass Microspheres (PW-HGMs), the key words here are Porous Wall. Almost every article has its beginning with the research done at the Savannah River National Laboratory (SRNL). The Savannah River Site (SRS) where SRNL is located has a long and successful history of working with hydrogen and its isotopes for national security, energy, waste management and environmental remediation applications. This includes more than 30 years of experience developing, processing, and implementing special ceramics, including glasses for a variety of Department of Energy (DOE) missions. In the case of glasses, SRS and SRNL have been involved in both the science and engineering of vitreous or glass based systems. As a part of this glass experience and expertise, SRNL has developed a number of niches in the glass arena, one of which is the development of porous glass systems for a variety of applications. These porous glass systems include sol gel glasses, which include both xerogels and aerogels, as well as phase separated glass compositions, that can be subsequently treated to produce another unique type of porosity within the glass forms. The porous glasses can increase the surface area compared to 'normal glasses of a 1 to 2 order of

  6. Biocompatible magnetic microspheres for Use in PDT and hyperthermia.

    PubMed

    Vaccari, C B; Cerize, N N P; Morais, P C; Ré, M I; Tedesco, A C

    2012-06-01

    Loaded microspheres with a silicon (IV) phthalocyanine derivative (NzPC) acting as a photosensitizer were prepared from polyhydroxybutyrate-co-valerate (PHBHV) and poly(ecaprolactone) (PCL) polymers using the emulsification solvent evaporation method (EE). The aim of our study was to prepare two systems of these biodegradable PHBHV/PCL microspheres. The first one containing only photosensitizer previously incorporated in the PHBHV and poly(ecaprolactone) (PCL) microspheres and the second one with the post magnetization of the DDS with magnetic nanoparticles. Magnetic fluid is successfully used for controlled incorporation of nanosized magnetic particles within the micron-sized template. This is the first time that we could get a successful pos incorporation of nanosized magnetic particles in a previously-prepared polymeric template. This procedure opens a great number of possibilities of post-functionalization of polymeric micro or nanoparticles with different bioactive materials. The NzPC release profile of the systems is ideal for PDT, the zeta potential and the size particle are stable upon aging in time. In vitro studies were evaluated using gingival fibroblastic cell line. The dark citotoxicity, the phototoxicity and the AC magnetic field assays of the as-prepared nanomagnetic composite were evaluated and the cellular viability analyzed by the classical test of MTT.

  7. Laser-Induced Spallation of Microsphere Monolayers.

    PubMed

    Hiraiwa, Morgan; Stossel, Melicent; Khanolkar, Amey; Wang, Junlan; Boechler, Nicholas

    2016-08-01

    The detachment of a semiordered monolayer of polystyrene microspheres adhered to an aluminum-coated glass substrate is studied using a laser-induced spallation technique. The microsphere-substrate adhesion force is estimated from substrate surface displacement measurements obtained using optical interferometry, and a rigid-body model that accounts for the inertia of the microspheres. The estimated adhesion force is compared with estimates obtained using an adhesive contact model together with interferometric measurements of the out-of-plane microsphere contact resonance, and with estimated work of adhesion values for the polystyrene-aluminum interface. Scanning electron microscope images of detached monolayer regions reveal a unique morphology, namely, partially detached monolayer flakes composed of single hexagonal close packed crystalline domains. This work contributes to the fields of microsphere adhesion and contact dynamics, and demonstrates a unique monolayer delamination morphology. PMID:27409715

  8. Preparation of floating microspheres for fish farming.

    PubMed

    Nepal, Pushp R; Chun, Myung-Kwan; Choi, Hoo-Kyun

    2007-08-16

    The aim of this study was to develop floating microspheres with practical applications to fish farming. Each microsphere with a central hollow cavity was prepared using a solvent diffusion and evaporation method with Eudragit E100. Various manufacturing parameters were investigated by single factor method. The macrolide antibiotic josamycin was selected as a model drug. The loading efficiency of the drug in the microspheres was 64.7%. In the release study, virtually none of the drug was released into the fresh water whereas the entire drug was released from the josamycin-loaded microspheres into the simulated gastric fluid of rainbow trout (pH 2.7). The buoyancy was excellent with approximately 90% of the microspheres still floating after 24h.

  9. Multiplexed Microsphere Suspension Array-Based Immunoassays.

    PubMed

    Lin, Andrew; Salvador, Alexandra; Carter, J Mark

    2015-01-01

    ELISA is an extremely powerful tool to detect analytes because of its sensitivity, selectivity, reproducibility and ease of use. Here we describe sandwich immunoassays performed in suspension on spectrally unique microspheres developed by Luminex. Luminex assays offer the benefit of multiplex analysis of large numbers of analytes in a single reaction. Because the microspheres are spectrally unique, many microspheres, each attached to various antibodies, can be added to a single sample. Luminex instruments can distinguish each microsphere and detect the intensity of a reporter signal for each microsphere. Results are reported in Median Fluorescent Intensities for each analyte. Luminex assays can be used to detect up to 500 analytes in a high-throughput format. Luminex refers to this technology as xMAP(®). Here we describe a routine protocol for a Luminex immunoassay. Other Luminex assays would have to be optimized for specific conditions according to their use. PMID:26160569

  10. Hierarchical ZnO-Ag-C composite porous microspheres with superior electrochemical properties as anode materials for lithium ion batteries.

    PubMed

    Xie, Qingshui; Ma, Yating; Zeng, Deqian; Zhang, Xiaoqiang; Wang, Laisen; Yue, Guanghui; Peng, Dong-Liang

    2014-11-26

    Hierarchical ZnO-Ag-C composite porous microspheres are successfully synthesized by calcination of the preproduced zinc-silver citrate porous microspheres in argon. The carbon derives from the in situ carbonization of carboxylic acid groups in zinc-silver citrate during annealing treatment. The average particle size of ZnO-Ag-C composite porous microspheres is approximate 1.5 μm. When adopted as the electrode materials in lithium ion batteries, the obtained composite porous microspheres display high specific capacity, excellent cyclability, and good rate capability. A discharge capacity as high as 729 mA h g(-1) can be retained after 200 cycles at 100 mA g(-1). The excellent electrochemical properties of ZnO-Ag-C are ascribed to its unique hierarchical porous configuration as well as the modification of silver and carbon.

  11. Solid evacuated microspheres of hydrogen

    DOEpatents

    Turnbull, Robert J.; Foster, Christopher A.; Hendricks, Charles D.

    1982-01-01

    A method is provided for producing solid, evacuated microspheres comprised of hydrogen. The spheres are produced by forming a jet of liquid hydrogen and exciting mechanical waves on the jet of appropriate frequency so that the jet breaks up into drops with a bubble formed in each drop by cavitation. The drops are exposed to a pressure less than the vapor pressure of the liquid hydrogen so that the bubble which is formed within each drop expands. The drops which contain bubbles are exposed to an environment having a pressure just below the triple point of liquid hydrogen and they thereby freeze giving solid, evacuated spheres of hydrogen.

  12. Injectable calcium hydroxylapatite microspheres (Radiesse).

    PubMed

    Ridenour, Brock; Kontis, Theda C

    2009-05-01

    Injectable calcium hydroxylapatite (Radiesse) received FDA approval in 2006 for the correction of facial lipoatrophy and moderate to severe facial wrinkles. This product consists of microspheres of a synthetic bone suspended in a methylcellulose gel matrix. Because the product is thicker than the hyaluronic acids, it is used for the correction of moderate to severe wrinkles, such as deep nasolabial folds. It is also used "off-label" to treat multiple areas of the face, nose, and hands. Radiesse is injected into the subdermal plane, and correction lasts approximately 1 year after injection.

  13. Nuclear fuel microsphere gamma analyzer

    DOEpatents

    Valentine, Kenneth H.; Long, Jr., Ernest L.; Willey, Melvin G.

    1977-01-01

    A gamma analyzer system is provided for the analysis of nuclear fuel microspheres and other radioactive particles. The system consists of an analysis turntable with means for loading, in sequence, a plurality of stations within the turntable; a gamma ray detector for determining the spectrum of a sample in one section; means for analyzing the spectrum; and a receiver turntable to collect the analyzed material in stations according to the spectrum analysis. Accordingly, particles may be sorted according to their quality; e.g., fuel particles with fractured coatings may be separated from those that are not fractured, or according to other properties.

  14. Raloxifene-/raloxifene-poly(ethylene glycol) conjugate-loaded microspheres: A novel strategy for drug delivery to bone forming cells.

    PubMed

    Kavas, Ayşegül; Keskin, Dilek; Altunbaş, Korhan; Tezcaner, Ayşen

    2016-08-20

    Raloxifene (Ral)- or Ral-poly(ethylene glycol) (PEG) conjugate-loaded microspheres were prepared with poly(ε-caprolactone) (PCL) alone or with the blend of PCL and poly(D,L-lactide-co-glycolide) (PLGA) to provide controlled and sustained Ral release systems. Benefits of these formulations were evaluated on bone regeneration. Ral-loaded PCL microspheres had the highest encapsulation efficiency (70.7±5.0%) among all groups owing to high hydrophobic natures of both Ral and PCL. Cumulative amount of Ral released from Ral-PEG (1:2) conjugate-loaded PCL:PLGA (1:1) microspheres (26.9±8.8%) after 60days was significantly higher relative to other microsphere groups. This finding can be ascribed to two factors: i) Ral-PEG conjugation, resulting in increased water-solubility of Ral and increased degradation rates of PCL and PLGA with enhanced water penetration into the polymer matrix, and ii) usage of PLGA besides PCL in the carrier composition to benefit from less hydrophobic and faster degradable nature of PLGA in comparison to PCL. In vitro cytotoxicity studies performed using adipose-derived mesenchymal stem cells (ASCs) demonstrated that all microspheres were non-toxic. Evaluation of intensities of Alizarin red S staining conducted after 7 and 14days of incubation of ASCs in the release media of the different microsphere groups was performed with Image J analysis software. At day 7, it was observed that the matrix deposited by the cells cultivated in the release medium of Ral-PEG (1:2) conjugate-loaded PCL:PLGA (1:1) microspheres had significantly higher mineral content (26.78±6.23%) than that of the matrix deposited by the cells cultivated in the release media of the other microsphere groups except Ral-loaded PCL:PLGA (1:1) microsphere group. At day 14, Ral release from Ral-PEG (1:2) conjugate-loaded PCL:PLGA (1:1) microsphere group resulted with significantly higher mineralization of the matrix (32.31±1.85%) deposited by ASCs in comparison to all other microsphere

  15. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres.

  16. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres. PMID:24854985

  17. Seeing is believing, PLGA microsphere degradation revealed in PLGA microsphere/PVA hydrogel composites.

    PubMed

    Gu, Bing; Sun, Xuanhao; Papadimitrakopoulos, Fotios; Burgess, Diane J

    2016-04-28

    The aim of this study was to understand the polymer degradation and drug release mechanism from PLGA microspheres embedded in a PVA hydrogel. Two types of microspheres were prepared with different molecular weight PLGA polymers (approximately 25 and 7 kDa) to achieve different drug release profiles, with a 9-day lag phase and without a lag phase, respectively. The kinetics of water uptake into the microspheres coincided with the drug release profiles for both formulations. For the 25 kDa microspheres, minimal water uptake was observed in the early part of the lag phase followed by substantial water uptake at the later stages and in the drug release phase. For the 7 kDa microspheres, water uptake occurred simultaneously with drug release. Water uptake was approximately 2-3 times that of the initial microsphere weight for both formulations. The internal structure of the PLGA microspheres was evaluated using low temperature scanning electron microscopy (cryo-SEM). Burst drug release occurred followed by pore forming from the exterior to the core of both microspheres. A well-defined hydrogel/microsphere interface was observed. For the 25 kDa microspheres, internal pore formation and swelling occurred before the second drug release phase. The surface layer of the microspheres remained intact whereas swelling, and degradation of the core continued throughout the drug release period. In addition, microsphere swelling reduced glucose transport through the coatings in PBS media and this was considered to be a as a consequence of the increased thickness of the coatings. The combination of the swelling and microdialysis results provides a fresh understanding on the competing processes affecting molecular transport of bioanalytes (i.e. glucose) through these composite coatings during prolonged exposure in PBS. PMID:26965956

  18. Aceclofenac microspheres: quality by design approach.

    PubMed

    Deshmukh, Rameshwar K; Naik, Jitendra B

    2014-03-01

    The purpose of this study was to prepare polymeric microspheres containing aceclofenac by single emulsion [oil-in-water (o/w)] solvent evaporation method. Two biocompatible polymers, ethylcellulose, and Eudragit® RS100 were used in combination. Seven processing factors were investigated by Plackett-Burman design (PBD) in order to enhance the encapsulation efficiency of the microspheres. A Plackett-Burman design was employed by using the Design-Expert® software (Version-8.0.7.1). The resultant microspheres were characterized for their size, morphology, encapsulation efficiency, and drug release. Imaging of particles was performed by field emission scanning electron microscopy. Interaction between the drug and polymers were investigated by Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffractometry (XRPD). Graphical and mathematical analyses of the design showed that Eudragit® RS100, and polyvinyl alcohol (PVA) were significant negative effect on the encapsulation efficiency and identified as the significant factor determining the encapsulation efficiency of the microspheres. The low magnitudes of error and the significant values of R(2) in the present investigation prove the high prognostic ability of the design. The microspheres showed high encapsulation efficiency (70.15% to 83.82%). The microspheres were found to be discrete, oval with smooth surface. The FTIR analysis confirmed the compatibility of aceclofenac with the polymers. The XRPD revealed the dispersion of drug within microspheres formulation. Perfect prolonged drug release profile over 12h was achieved by a combination of ethylcellulose, and Eudragit® RS100 polymers. In conclusion, polymeric microspheres containing aceclofenac can be successfully prepared using the technique of experimental design, and these results helped in finding the optimum formulation variables for encapsulation efficiency of microspheres. PMID:24433918

  19. Optical Tracking of Anomalous Diffusion Kinetics in Polymer Microspheres

    NASA Astrophysics Data System (ADS)

    Foreman, Matthew R.; Vollmer, Frank

    2015-03-01

    In this Letter we propose the use of whispering gallery mode resonance tracking as a label-free optical means to monitor diffusion kinetics in glassy polymer microspheres. Approximate solutions to the governing diffusion equations are derived for the case of slow relaxation and small Stefan number. Transduction of physical changes in the polymer, including formation of a rubbery layer, swelling, and dissolution, into detectable resonance shifts are described using a perturbative approach. Concrete examples of poly(methyl methacrylate) and polystyrene spheres in water are considered.

  20. Optical tracking of anomalous diffusion kinetics in polymer microspheres.

    PubMed

    Foreman, Matthew R; Vollmer, Frank

    2015-03-20

    In this Letter we propose the use of whispering gallery mode resonance tracking as a label-free optical means to monitor diffusion kinetics in glassy polymer microspheres. Approximate solutions to the governing diffusion equations are derived for the case of slow relaxation and small Stefan number. Transduction of physical changes in the polymer, including formation of a rubbery layer, swelling, and dissolution, into detectable resonance shifts are described using a perturbative approach. Concrete examples of poly(methyl methacrylate) and polystyrene spheres in water are considered.

  1. Chemical composition of plasma treated polyimide microspheres

    NASA Astrophysics Data System (ADS)

    Gawdzik, Barbara; Sobiesiak, Magdalena

    2003-05-01

    Synthetic carbon microspheres for chromatography were obtained from porous copolymer of 4,4'-bis(maleimidodiphenyl)methane (BM) and divinylbenzene (DVB) using arc discharge argon plasma treatment. Chemical structure of the obtained material was determined by elemental analysis, scanning electron microscopy with X-ray detector, acid and base titrations, and atomic absorption spectroscopy. The results suggest that the carbon microspheres contain copper coming from the plasma reactor electrodes. To remove it two complexion agents were used: EDTA and 20% HNO 3. Copper can be removed from the surface using these methods. The other amount was permanently built into internal structure of the microspheres.

  2. SRNL POROUS WALL GLASS MICROSPHERES

    SciTech Connect

    Wicks, G; Leung Heung, L; Ray Schumacher, R

    2008-04-15

    The Savannah River National Laboratory (SRNL) has developed a new medium for storage of hydrogen and other gases. This involves fabrication of thin, Porous Walled, Hollow Glass Microspheres (PW-HGMs), with diameters generally in the range of 1 to several hundred microns. What is unique about the glass microballons is that porosity has been induced and controlled within the thin, one micron thick walls, on the scale of 10 to several thousand Angstroms. This porosity results in interesting properties including the ability to use these channels to fill the microballons with special absorbents and other materials, thus providing a contained environment even for reactive species. Gases can now enter the microspheres and be retained on the absorbents, resulting in solid-state and contained storage of even reactive species. Also, the porosity can be altered and controlled in various ways, and even used to filter mixed gas streams within a system. SRNL is involved in about a half dozen different programs involving these PW-HGMs and an overview of some of these activities and results emerging are presented.

  3. Employees with Cerebral Palsy

    MedlinePlus

    ... Resources Home | Accommodation and Compliance Series: Employees with Cerebral Palsy (CP) By Eddie Whidden, MA Preface Introduction Information About ... SOAR) at http://AskJAN.org/soar. Information about Cerebral Palsy (CP) What is CP? Cerebral palsy is a ...

  4. Cerebral Aneurysms Fact Sheet

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS Cerebral Aneurysms Fact Sheet See a list of all NINDS ... I get more information? What is a cerebral aneurysm? A cerebral aneurysm (also known as an intracranial ...

  5. Titania coated hollow glass microspheres for environmental applications

    NASA Astrophysics Data System (ADS)

    Koopman, Mark C.

    The potential applicability of titania coated hollow glass microspheres (HGMs) to the photocatalytic degradation of microbiological and organic chemical water pollutants could have dramatic positive effects on improving the quality of industrial wastewaters that empty into rivers and streams, as well as potential use in economically improving the quality of drinking water. Heterogeneous photocatalysis using titania has been extensively studied since the 1990's because of its non-toxic nature, its high quantum yield of electrons and photo-holes, and its ability to use ambient solar radiation as a power source. Although titania embodies extraordinarily attractive properties for a range of environmental applications, a viable substrate or method of using the material effectively has not been recognized. HGMs are particularly attractive as a support for titania because of their low density and high surface area to volume ratio, but details of how they react to imposed loading, wear, and impact have not been addressed, nor have materials engineering analyses that could maximize their utility been made. In this study we have examined the microstructure, morphology and micro-compression properties of two types of titania coated hollow microspheres, a commercially produced HGM and cenospheres, a derivative of fly ash. Comparisons of uncoated and titania coated hollow microspheres showed improved failure loads and facture energies for the titania coated materials over the uncoated hollow microspheres. Also, the relationship between failure load and hollow microsphere diameter was characterized and the function employed to explain part of the gain in average failure load for the HGMs. Microscopic examination of titania coated HGMs that were subjected to various turbulent conditions, as well as intentional fracture, indicated good interfacial integrity, which supports the viability of both types of HGMs for potential applications. The photocatalytic reactivity of the titania

  6. Polylactic-co-glycolic acid microspheres containing three neurotrophic factors promote sciatic nerve repair after injury

    PubMed Central

    Zhao, Qun; Li, Zhi-yue; Zhang, Ze-peng; Mo, Zhou-yun; Chen, Shi-jie; Xiang, Si-yu; Zhang, Qing-shan; Xue, Min

    2015-01-01

    A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site; their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the microspheres at 300-μm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implantation, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve fibers were observed and distributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury. PMID:26604912

  7. Polylactic-co-glycolic acid microspheres containing three neurotrophic factors promote sciatic nerve repair after injury.

    PubMed

    Zhao, Qun; Li, Zhi-Yue; Zhang, Ze-Peng; Mo, Zhou-Yun; Chen, Shi-Jie; Xiang, Si-Yu; Zhang, Qing-Shan; Xue, Min

    2015-09-01

    A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site; their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the microspheres at 300-μm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implantation, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve fibers were observed and distributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.

  8. Cerebral microvascular effects of nimodipine in combination with soman.

    PubMed

    Koskinen, Lars-Owe D; Runnerstam, Magnus; Koch, Mona; Karlsson, Britt M

    2012-11-01

    Nimodipine, a calcium antagonist, has been shown to increase the detoxification of soman. In this study the cerebral microcirculatory effects of nimodipine and the acetylcholinesterase inhibitor soman was studied. Anaesthetised rats were administered nimodipine, 10 mg kg(-1) or vehicle intra-peritoneally, and 1h later exposed to 45 μg kg(-1) soman intravenously. The regional blood flows were measured using the microsphere method. Nimodipine and soman markedly increased the cerebral blood flow (CBF) and reduced the vascular resistance. Total CBF increased by 146% after nimodipine and by 105% after soman administration. Combined administration of nimodipine and soman caused additional but not fully additive effects on CBF and vascular resistance, indicating possible different mechanisms of the two agents. A part of the nimodipine induced increased detoxification after AChE-inhibition may be associated with this cerebral vasodilation.

  9. Organic aerogel microspheres and fabrication method therefor

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1996-04-16

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  10. Organic aerogel microspheres and fabrication method therefor

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1996-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  11. Method for introduction of gases into microspheres

    DOEpatents

    Hendricks, Charles D.; Koo, Jackson C.; Rosencwaig, Allan

    1981-01-01

    A method for producing small hollow glass spheres filled with a gas by introduction of the gas during formation of the hollow glass spheres. Hollow glass microspheres having a diameter up to about 500.mu. with both thin walls (0.5 to 4.mu.) and thick walls (5 to 20.mu.) that contain various fill gases, such as Ar, Kr, Xe, Br, DT, H.sub.2, D.sub.2, He, N.sub.2, Ne, CO.sub.2, etc. in the interior thereof, can be produced by the diffusion of the fill gas or gases into the microsphere during the formation thereof from a liquid droplet of glass-forming solution. This is accomplished by filling at least a portion of the multiple-zone drop-furnace used in producing hollow microspheres with the gas or gases of interest, and then taking advantage of the high rate of gaseous diffusion of the fill gas through the wall of the gel membrane before it transforms into a glass microsphere as it is processed in the multiple-zone furnace. Almost any gas can be introduced into the inner cavity of a glass microsphere by this method during the formation of the microsphere provided that the gas is diffused into the gel membrane or microsphere prior to its transformation into glass. The process of this invention provides a significant savings of time and related expense of filling glass microspheres with various gases. For example, the time for filling a glass microballoon with 1 atmosphere of DT is reduced from about two hours to a few seconds.

  12. Hydrogen transport and storage in engineered microspheres

    SciTech Connect

    Rambach, G.; Hendricks, C.

    1996-10-01

    This project is a collaboration between Lawrence Livermore National Laboratory (LLNL) and W.J. Schafer Associates (WJSA). The authors plan to experimentally verify the performance characteristics of engineered glass microspheres that are relevant to the storage and transport of hydrogen for energy applications. They will identify the specific advantages of hydrogen transport by microspheres, analyze the infrastructure implications and requirements, and experimentally measure their performance characteristics in realistic, bulk storage situations.

  13. Effects of forskolin on cerebral blood flow: implications for a role of adenylate cyclase

    SciTech Connect

    Wysham, D.G.; Brotherton, A.F.; Heistad, D.D.

    1986-11-01

    We have studied cerebral vascular effects of forskolin, a drug which stimulates adenylate cyclase and potentiates dilator effects of adenosine in other vascular beds. Our goals were to determine whether forskolin is a cerebral vasodilator and whether it potentiates cerebral vasodilator responses to adenosine. We measured cerebral blood flow with microspheres in anesthetized rabbits. Forskolin (10 micrograms/kg per min) increased blood flow (ml/min per 100 gm) from 39 +/- 5 (mean +/- S.E.) to 56 +/- 9 (p less than 0.05) in cerebrum, and increased flow to myocardium and kidney despite a decrease in mean arterial pressure. Forskolin did not alter cerebral oxygen consumption, which indicates that the increase in cerebral blood flow is a direct vasodilator effect and is not secondary to increased metabolism. We also examined effects of forskolin on the response to infusion of adenosine. Cerebral blood flow was measured during infusion of 1-5 microM/min adenosine into one internal carotid artery, under control conditions and during infusion of forskolin at 3 micrograms/kg per min i.v. Adenosine alone increased ipsilateral cerebral blood flow from 32 +/- 3 to 45 +/- 5 (p less than 0.05). Responses to adenosine were not augmented during infusion of forskolin. We conclude that forskolin is a direct cerebral vasodilator and forskolin does not potentiate cerebral vasodilator responses to adenosine.

  14. Indirect voltammetric determination of trace hydroxylamine using magnetic microspheres.

    PubMed

    Yang, Ming; Zhu, Jun-Jie

    2003-02-01

    A new indirect voltammetric method for the determination of hydroxylamine is described. It is based on the reduction of an electroactive derivative of hydroxylamine on the surface of a magnetic electrode. The electroactive derivative produced by hydroxylamine reacted with magnetic polymer microspheres containing carbonyl groups on the surface. The experimental conditions are discussed. It was found that the peak potential (Ep) of the derivative was -0.46 V (vs. Ag/AgCl) under optimum conditions. Hydroxylamine could be determined in the range of 5-2,000 microg l(-1) with the detection limit of 2 microg l(-1) and relative standard deviation for the determination of 100 microg l(-1) hydroxylamine was 2.35%. Satisfactory results were obtained for the determination of hydroxylamine in aqueous medium.

  15. Coacervate microspheres as carriers of recombinant adenoviruses.

    PubMed

    Kalyanasundaram, S; Feinstein, S; Nicholson, J P; Leong, K W; Garver, R I

    1999-01-01

    The therapeutic utility of recombinant adenoviruses (rAds) is limited in part by difficulties in directing the viruses to specific sites and by the requirement for bolus administration, both of which limit the efficiency of target tissue infection. As a first step toward overcoming these limitations, rAds were encapsulated in coacervate microspheres comprised of gelatin and alginate followed by stabilization with calcium ions. Ultrastructural evaluation showed that the microspheres formed in this manner were 0.8-10 microM in diameter, with viruses evenly distributed. The microspheres achieved a sustained release of adenovirus with a nominal loss of bioactivity. The pattern of release and the total amount of virus released was modified by changes in microsphere formulation. Administration of the adenovirus-containing microspheres to human tumor nodules engrafted in mice showed that the viral transgene was transferred to the tumor cells. It is concluded that coacervate microspheres can be used to encapsulate bioactive rAd and release it in a time-dependent manner.

  16. Demonstration of Microsphere Insulation in Cryogenic Vessels

    NASA Astrophysics Data System (ADS)

    Baumgartner, R. G.; Myers, E. A.; Fesmire, J. E.; Morris, D. L.; Sokalski, E. R.

    2006-04-01

    While microspheres have been recognized as a legitimate insulation material for decades, actual use in full-scale cryogenic storage tanks has not been demonstrated until now. The performance and life-cycle-cost advantages previously predicted have now been proven. Most bulk cryogenic storage tanks are insulated with either multilayer insulation (MLI) or perlite. Microsphere insulation, consisting of hollow glass bubbles, combines in a single material the desirable properties that other insulations only have individually. The material has high crush strength, low density, is noncombustible, and performs well in soft vacuum. These properties were proven during recent field testing of two 22,700-L (6,000-gallon) liquid nitrogen tanks, one insulated with microsphere insulation and the other with perlite. Normal evaporation rates (NER) for both tanks were monitored with precision test equipment and insulation levels within the tanks were observed through view ports as an indication of insulation compaction. Specific industrial applications were evaluated based on the test results and beneficial properties of microsphere insulation. Over-the-road trailers previously insulated with perlite will benefit not only from the reduced heat leak, but also the reduced mass of microsphere insulation. Economic assessments for microsphere-insulated cryogenic vessels including life-cycle cost are also presented.

  17. Cerebral Microdialysis.

    PubMed

    Young, Bethany; Kalanuria, Atul; Kumar, Monisha; Burke, Kathryn; Balu, Ramani; Amendolia, Olivia; McNulty, Kyle; Marion, BethAnn; Beckmann, Brittany; Ciocco, Lauren; Miller, Kimberly; Schuele, Donnamarie; Maloney-Wilensky, Eileen; Frangos, Suzanne; Wright, Danielle

    2016-03-01

    A variety of neuromonitoring techniques are available to aid in the care of neurocritically ill patients. However, traditional monitors lack the ability to measure brain biochemistry and may provide inadequate warning of potentially reversible deleterious conditions. Cerebral microdialysis (CMD) is a safe, novel method of monitoring regional brain biochemistry. Analysis of CMD analytes as part of a multimodal approach may help inform clinical decision making, guide medical treatments, and aid in prognostication of patient outcome. Its use is most frequently documented in traumatic brain injury and subarachnoid hemorrhage. Incorporating CMD into clinical practice is a multidisciplinary effort.

  18. Curvature capillary migration of microspheres.

    PubMed

    Sharifi-Mood, Nima; Liu, Iris B; Stebe, Kathleen J

    2015-09-14

    We address the question: how does capillarity propel microspheres along curvature gradients? For a particle on a fluid interface, there are two conditions that can apply at the three phase contact line: either the contact line adopts an equilibrium contact angle, or it can be pinned by kinetic trapping, e.g. at chemical heterogeneities, asperities, or other pinning sites on the particle surface. We formulate the curvature capillary energy for both scenarios for particles smaller than the capillary length and far from any pinning boundaries. The scale and range of the distortion made by the particle are set by the particle radius; we use singular perturbation methods to find the distortions and to rigorously evaluate the associated capillary energies. For particles with equilibrium contact angles, contrary to the literature, we find that the capillary energy is negligible, with the first contribution bounded to fourth order in the product of the particle radius and the deviatoric curvature of the host interface. For pinned contact lines, we find curvature capillary energies that are finite, with a functional form investigated previously by us for disks and microcylinders on curved interfaces. In experiments, we show microspheres migrate along deterministic trajectories toward regions of maximum deviatoric curvature with curvature capillary energies ranging from 6 × 10(3)-5 × 10(4)kBT. These data agree with the curvature capillary energy for the case of pinned contact lines. The underlying physics of this migration is a coupling of the interface deviatoric curvature with the quadrupolar mode of nanometric disturbances in the interface owing to the particle's contact line undulations. This work is an example of the major implications of nanometric roughness and contact line pinning for colloidal dynamics.

  19. Cerebral malaria.

    PubMed

    Postels, Douglas G; Birbeck, Gretchen L

    2013-01-01

    Malaria, the most significant parasitic disease of man, kills approximately one million people per year. Half of these deaths occur in those with cerebral malaria (CM). The World Health Organization (WHO) defines CM as an otherwise unexplained coma in a patient with malarial parasitemia. Worldwide, CM occurs primarily in African children and Asian adults, with the vast majority (greater than 90%) of cases occurring in children 5 years old or younger in sub-Saharan Africa. The pathophysiology of the disease is complex and involves infected erythrocyte sequestration, cerebral inflammation, and breakdown of the blood-brain barrier. A recently characterized malarial retinopathy is visual evidence of Plasmodium falciparum's pathophysiological processes occurring in the affected patient. Treatment consists of supportive care and antimalarial administration. Thus far, adjuvant therapies have not been shown to improve mortality rates or neurological outcomes in children with CM. For those who survive CM, residual neurological abnormalities are common. Epilepsy, cognitive impairment, behavioral disorders, and gross neurological deficits which include motor, sensory, and language impairments are frequent sequelae. Primary prevention strategies, including bed nets, vaccine development, and chemoprophylaxis, are in varied states of development and implementation. Continuing efforts to find successful primary prevention options and strategies to decrease neurological sequelae are needed. PMID:23829902

  20. Microsphere size, precipitation kinetics and drug distribution control drug release from biodegradable polyanhydride microspheres.

    PubMed

    Berkland, Cory; Kipper, Matt J; Narasimhan, Balaji; Kim, Kyekyoon Kevin; Pack, Daniel W

    2004-01-01

    A thorough understanding of the factors affecting drug release mechanisms from surface-erodible polymer devices is critical to the design of optimal delivery systems. Poly(sebacic anhydride) (PSA) microspheres were loaded with three model drug compounds (rhodamine B, p-nitroaniline and piroxicam) with a range of polarities (water solubilities). The drug release profiles from monodisperse particles of three different sizes were compared to release from polydisperse microspheres. Each of the model drugs exhibited different release mechanisms. Drug distribution within the polymer was investigated by laser scanning confocal microscopy and scanning electron microscopy. Rhodamine, the most hydrophilic compound investigated, was localized strongly toward the microsphere surface, while the much more hydrophobic compound, piroxicam, distributed more evenly. Furthermore, all three compounds were most uniformly distributed in the smallest microspheres, most likely due to the competing effects of drug diffusion out of the nascent polymer droplets and the precipitation of polymer upon solvent extraction, which effectively "traps" the drug in the polymer matrix. The differing drug distributions were manifested in the drug release profiles. Rhodamine was released very quickly independent of microsphere size. Thus, extended release profiles may not be obtainable if the drug strongly redistributes in the microspheres. The release of p-nitroaniline was more prolonged, but still showed little dependence on microsphere size. Hence, when water-soluble drugs are encapsulated with hydrophobic polymers, it may be difficult to tailor release profiles by controlling microsphere size. The piroxicam-loaded microspheres exhibit the most interesting release profiles, showing that release duration can be increased by decreasing microsphere size, resulting in a more uniform drug distribution. PMID:14684277

  1. [Cerebral palsy].

    PubMed

    Malagón Valdez, Jorge

    2007-01-01

    The term cerebral palsy (CP), is used for a great number of clinical neurological syndromes. The syndromes are characterized by having a common cause, motor defects. It is important, because they can cause a brain damage by presenting motor defects and some associated deficiencies, such as mental deficiency, epilepsy, language and visual defects and pseudobulbar paralysis, with the non-evolving fact. Some authors prefer using terms such as "non-evolving encephalopathies". In the treatment the utility of prevention programs of early stimulation and special rehabilitation methods, and treatment of associated deficiencies such as epilepsy, mental deficiency, language, audition and visual problems, and the attention deficit improve the prognosis in an important way. The prognosis depends on the severity of the disease and the associated manifestations. PMID:18422084

  2. Controlled study on the effect of pentoxifylline and an ergot alkaloid derivative on regional cerebral blood flow in patients with chronic cerebrovascular disease

    SciTech Connect

    Hartmann, A.; Tsuda, Y.

    1988-05-01

    Regional cerebral blood flow (rCBF) in 90 patients with CBF decreased due to vascular diseases was studied by using the xenon 133 inhalation technique and a 32-detector setup. Whereas 30 patients received their standard basic therapy only and were regarded as controls, 30 others received 3 x 2 mg/day of an ergot alkaloid (co-dergocrine mesylate), and 30 others received 3 x 400 mg pentoxifylline (slow-release formulation)/day orally. Therapy was performed for eight weeks and CBF measured before start of treatment, after a four-week treatment period, and at the end of the study. CBF did not change significantly in the control group; both the pentoxifylline and the ergot alkaloid group presented with a significant increase in the CBF. This positive effect was significantly more pronounced in the pentoxifylline group and affected more ischemic than other brain tissues. In addition, symptoms like sleep disturbances, vertigo, and tinnitus improved significantly during the pentoxifylline observation period.

  3. Computational dynamics of acoustically driven microsphere systems.

    PubMed

    Glosser, Connor; Piermarocchi, Carlo; Li, Jie; Dault, Dan; Shanker, B

    2016-01-01

    We propose a computational framework for the self-consistent dynamics of a microsphere system driven by a pulsed acoustic field in an ideal fluid. Our framework combines a molecular dynamics integrator describing the dynamics of the microsphere system with a time-dependent integral equation solver for the acoustic field that makes use of fields represented as surface expansions in spherical harmonic basis functions. The presented approach allows us to describe the interparticle interaction induced by the field as well as the dynamics of trapping in counter-propagating acoustic pulses. The integral equation formulation leads to equations of motion for the microspheres describing the effect of nondissipative drag forces. We show (1) that the field-induced interactions between the microspheres give rise to effective dipolar interactions, with effective dipoles defined by their velocities and (2) that the dominant effect of an ultrasound pulse through a cloud of microspheres gives rise mainly to a translation of the system, though we also observe both expansion and contraction of the cloud determined by the initial system geometry. PMID:26871188

  4. Dosimetry of in situ activated dysprosium microspheres.

    PubMed

    Adnani, N

    2004-03-01

    This paper presents the results of a study aimed at investigating the dosimetry of stable dysprosium microspheres activated, in situ, by a linac generated photon beam. In phantom measurements of the neutron flux within an 18 MV photon beam were performed using CR-39 detectors and gold activation. The results were used in conjunction with a Monte Carlo computer simulation to investigate the dose distribution resulting from the activation of dysprosium (Dy) microspheres using an 18 MV photon beam. Different depths, lesion volumes and volume concentrations of microspheres are investigated. The linac lower collimator jaws are assumed completely closed to shield the tumour volume from the photon dose. Using a single AP field with 0 x 0 cm2 field size (closed jaws), a photon dose rate of 600 MU min(-1) and 80 cm SSD for 10 min, an average dose exceeding 1 Gy can be delivered to spherical lesions of 0.5 cm and higher diameter. The variation of the average dose with the size of the lesion reaches saturation for tumour volumes exceeding 1 cm in diameter. This report shows that the photon beam of a high-energy linac can be used to activate Dy microspheres in situ and, as a result, deliver a significant dose of beta radiation. Non-radioactive Dy microspheres do not have the toxicity and imaging problems associated with commercially available yttrium-90 based products. PMID:15070199

  5. Computational dynamics of acoustically driven microsphere systems.

    PubMed

    Glosser, Connor; Piermarocchi, Carlo; Li, Jie; Dault, Dan; Shanker, B

    2016-01-01

    We propose a computational framework for the self-consistent dynamics of a microsphere system driven by a pulsed acoustic field in an ideal fluid. Our framework combines a molecular dynamics integrator describing the dynamics of the microsphere system with a time-dependent integral equation solver for the acoustic field that makes use of fields represented as surface expansions in spherical harmonic basis functions. The presented approach allows us to describe the interparticle interaction induced by the field as well as the dynamics of trapping in counter-propagating acoustic pulses. The integral equation formulation leads to equations of motion for the microspheres describing the effect of nondissipative drag forces. We show (1) that the field-induced interactions between the microspheres give rise to effective dipolar interactions, with effective dipoles defined by their velocities and (2) that the dominant effect of an ultrasound pulse through a cloud of microspheres gives rise mainly to a translation of the system, though we also observe both expansion and contraction of the cloud determined by the initial system geometry.

  6. Perfusion MRI Derived Indices of Microvascular Shunting and Flow Control Correlate with Tumor Grade and Outcome in Patients with Cerebral Glioma

    PubMed Central

    Tietze, Anna; Mouridsen, Kim; Lassen-Ramshad, Yasmin; Østergaard, Leif

    2015-01-01

    Objectives Deficient microvascular blood flow control is thought to cause tumor hypoxia and increase resistance to therapy. In glioma patients, we tested whether perfusion-weighted MRI (PWI) based indices of microvascular flow control provide more information on tumor grade and patient outcome than does the established PWI angiogenesis marker, cerebral blood volume (CBV). Material and Methods Seventy-two glioma patients (sixty high-grade, twelve low-grade gliomas) were included. Capillary transit time heterogeneity (CTH) and the coefficient of variation (COV), its ratio to blood mean transit time, provide indices of microvascular flow control and the extent to which oxygen can be extracted by tumor tissue. The ability of these parameters and CBV to differentiate tumor grade were assessed by receiver operating characteristic curves and logistic regression. Their ability to predict time to progression and overall survival was examined by the Cox proportional-hazards regression model, and by survival curves using log-rank tests. Results The best prediction of grade (AUC = 0.876; p < 0.05) was achieved by combining knowledge of CBV and CTH in the enhancing tumor and peri-focal edema, and patients with glioblastoma multiforme were identified best by CTH (AUC = 0.763; p<0.001). CTH outperformed CBV and COV in predicting time to progression and survival in all gliomas and in a subgroup consisting of only high-grade gliomas. Conclusion Our study confirms the importance of microvascular flow control in tumor growth by demonstrating that determining CTH improves tumor grading and outcome prediction in glioma patients compared to CBV alone. PMID:25875182

  7. Localized drugs delivery hydroxyapatite microspheres for osteoporosis therapy

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Ko, I. H.; Jeon, S.-H.; Chae, J. H.; Lee, E. J.; Chang, J. H.

    2011-10-01

    This study describes the preparation of hydroxyapatite microspheres for local drugs delivery. The formation of the hydroxyapatite microspheres was initiated by enzymatic decomposition of urea and accomplished by emulsification process (water-in-oil). The microspheres obtained were sintered at 500°C. Scanning electron microscope (SEM) indicated that the microspheres have various porous with random size, which maximizes the surface area. Cytotoxicity was not observed after sintering. Osteoporosis drugs, alendronate and BMP-2, were loaded into HAp microspheres and the releases of both molecules showed sustained releasing profiles.

  8. Acrolein Microspheres Are Bonded To Large-Area Substrates

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan; Yen, Richard C. K.

    1988-01-01

    Reactive cross-linked microspheres produced under influence of ionizing radiation in aqueous solutions of unsaturated aldehydes, such as acrolein, with sodium dodecyl sulfate. Diameters of spheres depend on concentrations of ingredients. If polystyrene, polymethylmethacrylate, or polypropylene object immersed in solution during irradiation, microspheres become attached to surface. Resulting modified surface has grainy coating with reactivity similar to free microspheres. Aldehyde-substituted-functional microspheres react under mild conditions with number of organic reagents and with most proteins. Microsphere-coated macrospheres or films used to immobilize high concentrations of proteins, enzymes, hormones, viruses, cells, and large number of organic compounds. Applications include separation techniques, clinical diagnostic tests, catalytic processes, and battery separators.

  9. Biosensing by WGM Microspherical Resonators

    PubMed Central

    Righini, Giancarlo C.; Soria, Silvia

    2016-01-01

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 108–109 lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed. PMID:27322282

  10. Biosensing by WGM Microspherical Resonators.

    PubMed

    Righini, Giancarlo C; Soria, Silvia

    2016-01-01

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 10⁸-10⁸ lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed. PMID:27322282

  11. Biosensing by WGM Microspherical Resonators.

    PubMed

    Righini, Giancarlo C; Soria, Silvia

    2016-06-17

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 10⁸-10⁸ lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed.

  12. Cold Atmospheric Plasma Modified Electrospun Scaffolds with Embedded Microspheres for Improved Cartilage Regeneration

    PubMed Central

    Zhu, Wei; Castro, Nathan J.; Cheng, Xiaoqian; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Articular cartilage is prone to degeneration and possesses extremely poor self-healing capacity due to inherent low cell density and the absence of a vasculature network. Tissue engineered cartilage scaffolds show promise for cartilage repair. However, there still remains a lack of ideal biomimetic tissue scaffolds which effectively stimulate cartilage regeneration with appropriate functional properties. Therefore, the objective of this study is to develop a novel biomimetic and bioactive electrospun cartilage substitute by integrating cold atmospheric plasma (CAP) treatment with sustained growth factor delivery microspheres. Specifically, CAP was applied to a poly(ε-caprolactone) electrospun scaffold with homogeneously distributed bioactive factors (transforming growth factor-β1 and bovine serum albumin) loaded poly(lactic-co-glycolic) acid microspheres. We have shown that CAP treatment renders electrospun scaffolds more hydrophilic thus facilitating vitronectin adsorption. More importantly, our results demonstrate, for the first time, CAP and microspheres can synergistically enhance stem cell growth as well as improve chondrogenic differentiation of human marrow-derived mesenchymal stem cells (such as increased glycosaminoglycan, type II collagen, and total collagen production). Furthermore, CAP can substantially enhance 3D cell infiltration (over two-fold increase in infiltration depth after 1 day of culture) in the scaffolds. By integrating CAP, sustained bioactive factor loaded microspheres, and electrospinning, we have fabricated a promising bioactive scaffold for cartilage regeneration. PMID:26222527

  13. Cold Atmospheric Plasma Modified Electrospun Scaffolds with Embedded Microspheres for Improved Cartilage Regeneration.

    PubMed

    Zhu, Wei; Castro, Nathan J; Cheng, Xiaoqian; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Articular cartilage is prone to degeneration and possesses extremely poor self-healing capacity due to inherent low cell density and the absence of a vasculature network. Tissue engineered cartilage scaffolds show promise for cartilage repair. However, there still remains a lack of ideal biomimetic tissue scaffolds which effectively stimulate cartilage regeneration with appropriate functional properties. Therefore, the objective of this study is to develop a novel biomimetic and bioactive electrospun cartilage substitute by integrating cold atmospheric plasma (CAP) treatment with sustained growth factor delivery microspheres. Specifically, CAP was applied to a poly(ε-caprolactone) electrospun scaffold with homogeneously distributed bioactive factors (transforming growth factor-β1 and bovine serum albumin) loaded poly(lactic-co-glycolic) acid microspheres. We have shown that CAP treatment renders electrospun scaffolds more hydrophilic thus facilitating vitronectin adsorption. More importantly, our results demonstrate, for the first time, CAP and microspheres can synergistically enhance stem cell growth as well as improve chondrogenic differentiation of human marrow-derived mesenchymal stem cells (such as increased glycosaminoglycan, type II collagen, and total collagen production). Furthermore, CAP can substantially enhance 3D cell infiltration (over two-fold increase in infiltration depth after 1 day of culture) in the scaffolds. By integrating CAP, sustained bioactive factor loaded microspheres, and electrospinning, we have fabricated a promising bioactive scaffold for cartilage regeneration. PMID:26222527

  14. Sonochemical proteinaceous microspheres for wound healing.

    PubMed

    Silva, Raquel; Ferreira, Helena; Vasconcelos, Andreia; Gomes, Andreia C; Cavaco-Paulo, Artur

    2012-01-01

    In this work, we report a novel approach using proteinaceous microspheres of bovine serum albumin (BSA), human serum albumin (HSA) and silk fibroin (SF) containing different organic solvents, namely n-dodecane, mineral oil and vegetable oil, to reduce the activity of human neutrophil elastase (HNE) found in high levels on chronic wounds. The ability of these devices to inhibit HNE was evaluated using porcine pancreatic elastase (PPE) solution as a model of wound exudates. The results obtained indicated that the level of PPE activity can be tuned by changing the organic solvent present on different protein microspheres, thus showing an innovative way of controlling the elastase-antielastase imbalance found in chronic wounds. Furthermore, these proteinaceous microspheres were shown to be important carriers of elastase inhibitors causing no cytotoxicity in human skin fibroblasts in vitro, making them suitable for biomedical applications, such as chronic wounds.

  15. Redox-responsive alginate microsphere containing cystamine.

    PubMed

    Kwon, Kyeongnan; Kim, Jin-Chul

    2016-10-01

    Redox-responsive microspheres were prepared by solidifying the alginate- and cystamine-containing water droplets of O/W emulsion using calcium ion. Emulsions were prepared using alginate/cystamine mixture solution whose the carboxylic group/the amino group molar ratio was 1:1, 1:2, and 1:3, and whose the total concentration was kept to 2% (w/v). The microspheres on Scanning electron microscopy photographs were almost spherical and they were less than 1 μm in diameter. According to the energy-dispersive X-ray spectroscopy, the sulfur content of the microspheres was found to be 6.1, 11.4, and 14.8% (w/w), respectively, not markedly different from the calculated content. The release degree of blue dextran loaded in the microspheres was higher as the cystamine content was higher. Microspheres released almost the same amount of dye regardless of dithiothreitol (DTT, a reducing agent) concentration when the cystamine content was relatively low (e.g. 14.5% (w/w)), whereas they released dye in DTT concentration-dependent manner when the cystamine content was relatively high (e.g. 27.0 and 35.1% (w/w)). The light scattering intensity of alginate/cystamine mixture solution was stronger at a larger amount of cystamine, indicating that cystamine could cross-link alginate chains. The light scattering intensity decreased with increasing DTT concentration, possibly because of the breakdown of the disulfide bond of cystamine. The breakdown of the disulfide bond could account for why the DTT concentration-dependent release of dye loaded in the microspheres was observed. PMID:27484719

  16. Cell specific, variable density, polymer microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1977-01-01

    Biocompatible polymeric microspheres having an average diameter below about 3 microns and having density at least 15% greater or lesser than organic cells and having covalent binding sites are provided in accordance with this invention. The microspheres are obtained by copolymerizing a hydroxy or amine substituted acrylic monomer such as hydroxyethylmethacrylate with a light or dense comonomer such as a fluoromonomer. A lectin or antibody is bound to the hydroxy or amine site of the bead to provide cell specificity. When added to a cell suspension the marked bead will specifically label the cell membrane by binding to specific receptor sites thereon. The labelled membrane can then be separated by density gradient centrifugation.

  17. Quantum Magnetomechanics with Levitating Superconducting Microspheres

    NASA Astrophysics Data System (ADS)

    Romero-Isart, O.; Clemente, L.; Navau, C.; Sanchez, A.; Cirac, J. I.

    2012-10-01

    We show that by magnetically trapping a superconducting microsphere close to a quantum circuit, it is possible to perform ground-state cooling and prepare quantum superpositions of the center-of-mass motion of the microsphere. Due to the absence of clamping losses and time-dependent electromagnetic fields, the mechanical motion of micrometer-sized metallic spheres in the Meissner state is predicted to be very well isolated from the environment. Hence, we propose to combine the technology of magnetic microtraps and superconducting qubits to bring relatively large objects to the quantum regime.

  18. Unusual imaging properties of superresolution microspheres.

    PubMed

    Li, Pin-Yi; Tsao, Yang; Liu, Yun-Ju; Lou, Zong-Xing; Lee, Wei-Li; Chu, Shi-Wei; Chang, Chih-Wei

    2016-07-25

    We employ a self-assembly method to fabricate dielectric microsphere arrays that can be transferred to any desired positions. The arrays not only enable far-field, broad-band, high-speed, large-area, and wide-angle field of views but also achieve superresolution reaching λ/6.4. We also find that many proposed theories are insufficient to explain the imaging properties; including the achieved superresolution, effects of immersion, and unusual size-dependent magnification. The half-immersed microspheres certainly do not behave like any ordinary solid immersion lenses and new mechanisms must be incorporated to explain their unusual imaging properties. PMID:27464101

  19. Cerebral Contusions and Lacerations

    MedlinePlus

    ... Stretch Additional Content Medical News Cerebral Contusions and Lacerations By James E. Wilberger, MD, Derrick A. Dupre, ... a direct, strong blow to the head. Cerebral lacerations are tears in brain tissue, caused by a ...

  20. Cerebral aneurysm (image)

    MedlinePlus

    ... area within the vessel wall. If a cerebral (brain) aneurysm ruptures, the escaping blood within the brain may cause severe neurologic complications or death. A person who has a ruptured cerebral aneurysm may complain of the sudden onset of "the ...

  1. United Cerebral Palsy

    MedlinePlus

    ... be sure to follow us on Twitter . United Cerebral Palsy UCP educates, advocates and provides support services to ... Partners Merz Logo Sprint Relay Copyright © 2015 United Cerebral Palsy 1825 K Street NW Suite 600 Washington, DC ...

  2. Facile Synthesis of Porous Nickel/Carbon Composite Microspheres with Enhanced Electromagnetic Wave Absorption by Magnetic and Dielectric Losses.

    PubMed

    Qiu, Song; Lyu, Hailong; Liu, Jiurong; Liu, Yuzhen; Wu, Nannan; Liu, Wei

    2016-08-10

    Porous nickel/carbon (Ni/C) composite microspheres with diameters of ca. 1.2-1.5 μm were fabricated by a solvothermal method combined with carbon reduction. The pore size of the synthesized Ni/C composite microspheres ranged from several nanometers to 50 nm. The porous Ni/C composite microspheres exhibited a saturation magnetization (MS) of 53.5 emu g(-1) and a coercivity (HC) of 51.4 Oe. When tested as an electromagnetic (EM) wave absorption material, the epoxy resin composites containing 60% and 75% porous Ni/C microspheres provided high-performance EM wave absorption at thicknesses of 3.0-11.0 and 1.6-7.0 mm in the corresponding frequency ranges of 2.0-12 and 2.0-18 GHz, respectively. The superior EM wave absorption performances of porous Ni/C composite microspheres were derived from the synergy effects generated by the magnetic loss of nickel, the dielectric loss of carbon, and the porous structure. PMID:27441382

  3. Facile Synthesis of Porous Nickel/Carbon Composite Microspheres with Enhanced Electromagnetic Wave Absorption by Magnetic and Dielectric Losses.

    PubMed

    Qiu, Song; Lyu, Hailong; Liu, Jiurong; Liu, Yuzhen; Wu, Nannan; Liu, Wei

    2016-08-10

    Porous nickel/carbon (Ni/C) composite microspheres with diameters of ca. 1.2-1.5 μm were fabricated by a solvothermal method combined with carbon reduction. The pore size of the synthesized Ni/C composite microspheres ranged from several nanometers to 50 nm. The porous Ni/C composite microspheres exhibited a saturation magnetization (MS) of 53.5 emu g(-1) and a coercivity (HC) of 51.4 Oe. When tested as an electromagnetic (EM) wave absorption material, the epoxy resin composites containing 60% and 75% porous Ni/C microspheres provided high-performance EM wave absorption at thicknesses of 3.0-11.0 and 1.6-7.0 mm in the corresponding frequency ranges of 2.0-12 and 2.0-18 GHz, respectively. The superior EM wave absorption performances of porous Ni/C composite microspheres were derived from the synergy effects generated by the magnetic loss of nickel, the dielectric loss of carbon, and the porous structure.

  4. Fibronectin purification from human plasma in a packed-bed column system with gelatin immobilized PHEMA microspheres.

    PubMed

    Kayirhan-Denizli, F; Arica, M Y; Denizli, A

    2001-01-01

    Bioaffinity chromatography has a unique and powerful role that is used as a purification tool in the production of therapeutic plasma protein derivatives. In this study, a bioaffinity-ligand, i.e. gelatin, was covalently immobilized with PHEMA microspheres (150-200 microm in diameter). The affinity sorbent carrying 7.5 mg gelatin g(-1) polymer was then used to separate fibronectin from human plasma in a packed-bed column system. Fibronectin separation from human plasma on unmodified PHEMA microspheres was 0.45 mg g(-1), while much higher adsorption values, up to 21.8 mg g(-1), were obtained with gelatin-immobilized microspheres. The fibronectin adsorption capacity of the microspheres decreased with an increase in the recirculation rate of plasma. Fibronectin adsorption increased with decreasing temperature, and the maximum adsorption achieved at 4 degrees C (26.3 mg fibronectin g(-1)). Up to 94.7% of the adsorbed fibronectin was desorbed by using 2 M urea in the presence of 1 M sodium chloride as elution agent. The adsorption-desorption cycle was repeated ten times using the same affinity column. There was no remarkable reduction in the adsorption capacity of the gelatin-immobilized PHEMA microspheres. PMID:11469779

  5. Hierarchical TiO2 microspheres comprised of anatase nanospindles for improved electron transport in dye-sensitized solar cells.

    PubMed

    Wu, Dapeng; Wang, Yi; Dong, Hui; Zhu, Feng; Gao, Shuyan; Jiang, Kai; Fu, Limin; Zhang, Jianping; Xu, Dongsheng

    2013-01-01

    Hierarchical TiO(2) microspheres assembled by nanospindles were prepared via a two-step hydrothermal method. The as-prepared products have uniform diameters of ~450 nm and surface area of ~88 m(2) g(-1). The optical investigation evidenced that the photoanode film has a prominent light scattering effect at a wavelength range of 600-800 nm and possesses enhanced dye loading capacity. In addition, the electron recombination and transport dynamic measurements indicated that these hierarchical products could suppress the recombination and improve the diffusion coefficient of the photoelectrons, which can be attributed to the improvement of the connectivity by bridging the neighbouring microspheres through the embedded nanospindles. As a result, a high power conversion efficiency of 8.5% was demonstrated, indicating a ~30% improvement compared with the cell derived from the well-defined nanocrystalline microspheres (6.5%). PMID:23165289

  6. Aging and Cerebral Palsy.

    ERIC Educational Resources Information Center

    Networker, 1993

    1993-01-01

    This special edition of "The Networker" contains several articles focusing on aging and cerebral palsy (CP). "Aging and Cerebral Palsy: Pathways to Successful Aging" (Jenny C. Overeynder) reports on the National Invitational Colloquium on Aging and Cerebral Palsy held in April 1993. "Observations from an Observer" (Kathleen K. Barrett) describes…

  7. The development of colour-encapsulated microspheres for novel colour cosmetics.

    PubMed

    Jones, Stephen R; Grey, Bryan D; Mistry, Kishor K; Wildgust, Paul G

    2009-06-01

    In the present study, the preparation, characterization and colour retention properties of organic colour-loaded microspheres are described. The study aimed to produce shatter-resistant, low-bleeding polymeric microspheres with particle diameters of 20 µm containing 10-20% (w/w) of the Food, Drug, and Cosmetic grade colourants FD&C Blue No. 1 Al Lake, FD&C Yellow No. 5 Al Lake and D&C Red No. 36 by utilizing an aqueous-dispersed polymer water-in-oil (W/O) solvent evaporation process featuring styrene/acrylates-based copolymers. The influences of matrix polymeric components on the shape, integrity and dye retention of the microspheres were studied. Encapsulation matrices based on alkali soluble polymers yielded misshapen spheroids that were prone both to swelling and decreased dye retention in aqueous environments, as well as loss of shape at 70°C in cosmetic oils under shear. A resin supported emulsion (RSE)-based matrix, in comparison, yielded highly spherical microspheres resistant to shape deformation and swelling. Additions of up to 15% (w/w) of an alkali soluble polymer to the RSE system improved colour dispersion without detrimentally affecting the structural integrity of the microspheres while also slightly decreasing dye concentrations released into aqueous solutions. The in vitro dye release of the colour-loaded microspheres in a cosmetic-type water-in-silicone (W/Si) emulsion was evaluated and compared to the in vitro dye release studies in aqueous solutions. No direct correlations between the emulsion system and single-component aqueous solutions could be made. Dye-release levels evaluated from contacting the microspheres with a complex aqueous medium (CAM5), which incorporated ingredient classes typically encountered in the aqueous phase of an emulsion, were found to correlate to levels determined in the generic W/Si emulsion with a 93% linear regression between the data sets. This study demonstrates that the CAM5 protocol (or, alternatively, a CAM2

  8. Method for introduction of gases into microspheres

    DOEpatents

    Hendricks, C.D.; Koo, J.C.; Rosencwaig, A.

    A method is described for producing small hollow glass spheres filled with a gas by introduction of the gas during formation of the hollow glass spheres. Hollow glass microspheres having a diameter up to about 500..mu.. with both thin walls (0.5 to 4/sub ..mu../) and thick walls (5 to 20/sub ..mu../) that contain various fill gases, such as Ar, Kr, Xe, Br, D, H/sub 2/, DT, He, N/sub 2/, Ne, CO/sub 2/, etc., in the interior thereof, can be produced by the diffusion of the fill gas or gases into the microsphere during the formation thereof from a liquid droplet of glass-form-forming solution. This is accomplished by filling at least a portion of the multiple-zone drop-furnace used in producing hollow microspheres with the gas or gases of interest, and then taking advantage of the high rate of gaseous diffusion of the fill gas through the wall of the gel membrane before it transforms into a glass microsphere as it is processed in the multiple-zone furnace.

  9. Preparation of small bio-compatible microspheres

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Dreyer, William J. (Inventor)

    1979-01-01

    Small, round, bio-compatible microspheres capable of covalently bonding proteins and having a uniform diameter below about 3500 A are prepared by substantially instantaneously initiating polymerization of an aqueous emulsion containing no more than 35% total monomer including an acrylic monomer substituted with a covalently bondable group such a hydroxyl, amino or carboxyl and a minor amount of a cross-linking agent.

  10. Beat-Frequency/Microsphere Medical Ultrasonic Imaging

    NASA Technical Reports Server (NTRS)

    Yost, William T.; Cantrell, John H.; Pretlow, Robert A., III

    1995-01-01

    Medical ultrasonic imaging system designed to provide quantitative data on various flows of blood in chambers, blood vessels, muscles, and tissues of heart. Sensitive enough to yield readings on flows of blood in heart even when microspheres used as ultrasonic contrast agents injected far from heart and diluted by circulation of blood elsewhere in body.

  11. 21 CFR 870.1360 - Trace microsphere.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... within or to an organ. (b) Classification. Class III (premarket approval). (c) Date PMA or notice of completion of a PDP is required. A PMA or notice of completion of a PDP is required to be filed with the Food... other trace microsphere shall have an approved PMA or a declared completed PDP in effect before...

  12. 21 CFR 870.1360 - Trace microsphere.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... within or to an organ. (b) Classification. Class III (premarket approval). (c) Date PMA or notice of completion of a PDP is required. A PMA or notice of completion of a PDP is required to be filed with the Food... other trace microsphere shall have an approved PMA or a declared completed PDP in effect before...

  13. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    PubMed

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate.

  14. Cerebral aneurysms: Formation, progression and developmental chronology

    PubMed Central

    Etminan, Nima; Buchholz, Bruce A.; Dreier, Rita; Bruckner, Peter; Torner, James C.; Steiger, Hans-Jakob; Hänggi, Daniel; Macdonald, R. Loch

    2015-01-01

    The prevalence of unruptured intracranial aneurysms (UAIs) in the general population is up to 3%. Existing epidemiological data suggests that only a small fraction of UIAs progress towards rupture over the lifetime of an individual, but the surrogates for subsequent rupture and the natural history of UIAs are discussed very controversially at present. In case of rupture of an UIA, the case-fatality is up to 50%, which therefore continues to stimulate interest in the pathogenesis of cerebral aneurysm formation and progression. Actual data on the chronological development of cerebral aneurysm has been especially difficult to obtain and, until recently, the existing knowledge in this respect is mainly derived from animal or mathematical models or short-term observational studies. Here, we highlight the current data on cerebral aneurysm formation and progression as well as a novel approach to investigate the developmental chronology of cerebral aneurysms. PMID:24323717

  15. Electrostatic Assembly of Sandwich-like Ag-C@ZnO-C@Ag-C Hybrid Hollow Microspheres with Excellent High-Rate Lithium Storage Properties.

    PubMed

    Xie, Qingshui; Ma, Yating; Wang, Xuanpeng; Zeng, Deqian; Wang, Laisen; Mai, Liqiang; Peng, Dong-Liang

    2016-01-26

    Herein, we introduce a facile electrostatic attraction approach to produce zinc-silver citrate hollow microspheres, followed by thermal heating treatment in argon to ingeniously synthesize sandwich-like Ag-C@ZnO-C@Ag-C hybrid hollow microspheres. The 3D carbon conductive framework in the hybrids derives from the in situ carbonation of carboxylate acid groups in zinc-silver citrate hollow microspheres during heating treatment, and the continuous and homogeneous Ag nanoparticles on the outer and inner surfaces of hybrid hollow microspheres endow the shells with the sandwiched configuration (Ag-C@ZnO-C@Ag-C). When applied as the anode materials for lithium ion batteries, the fabricated hybrid hollow microspheres with sandwich-like shells reveal a very large reversible capacity of 1670 mAh g(-1) after 200 cycles at a current density of 0.2 A g(-1). Even at the very large current densities of 1.6 and 10.0 A g(-1), the high specific capacities of about 1063 and 526 mAh g(-1) can be retained, respectively. The greatly enhanced electrochemical properties of Ag-C@ZnO-C@Ag-C hybrid microspheres are attributed to their special structural features such as the hollow structures, the sandwich-like shells, and the nanometer-sized building blocks.

  16. Changes in the lactate threshold during treadmill exercise after microsphere-induced infarction in rats.

    PubMed

    Takahashi, Hisashi; Himi, Naoyuki; Kuniyasu, Katsushi; Koga, Tomoshige

    2012-11-01

    The aim of this study was to clarify changes in the lactate threshold (LT) in the acute period after cerebral infarction. Cerebral infarction was induced by the injection of microspheres (MS) into the right internal carotid artery. To estimate the degree of neurologic deficit caused by surgery, the behaviors of all rats were evaluated in terms of typical symptoms of stroke in rats. The rotarod test was used to evaluate equilibrium function. Rats were forced to perform stepwise treadmill exercises, and serial changes in blood lactate concentration were measured for determination of the LT. The average treadmill speed at the LT and the rotarod test performance in MS rats was significantly lower than those in sham-operated rats on postsurgery day 2. However, although neurologic deficits disappeared on postsurgery day 7 in MS rats, LT level and rotarod test performance were significantly lower than in sham-operated rats. These results suggest that the decrease in LT in the acute period after cerebral infarction might be induced by impaired equilibrium function. Other possibilities are discussed as well.

  17. Preparation and evaluation of sustained release loxoprofen loaded microspheres

    PubMed Central

    Venkatesan, P.; Manavalan, R.; Valliappan, K.

    2011-01-01

    The aim of present study was to formulate and evaluate the loxoprofen loaded Sustained release microspheres by emulsion solvent evaporation technique. Ethylcellulose, a biocompatible polymer is used as the retardant material. The effects of process conditions such as drug loading, polymer type and solvent type on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their particle size and drug loading and drug release. The in-vitro release studies were carried out in phosphate buffer at pH 7.4. The prepared microspheres were white, free flowing and spherical in shape. The drug-loaded microspheres showed 71.2% of entrapment and the in-vitro release studies showed that Loxoprofen microspheres of 1:3 ratios showed better sustained effect over a period of 8 hours PMID:24826017

  18. Method of detecting luminescent target ions with modified magnetic microspheres

    DOEpatents

    Shkrob, Ilya A; Kaminski, Michael D

    2014-05-13

    This invention provides methods of using modified magnetic microspheres to extract target ions from a sample in order to detect their presence in a microfluidic environment. In one or more embodiments, the microspheres are modified with molecules on the surface that allow the target ions in the sample to form complexes with specific ligand molecules on the microsphere surface. In one or more embodiments, the microspheres are modified with molecules that sequester the target ions from the sample, but specific ligand molecules in solution subsequently re-extract the target ions from the microspheres into the solution, where the complexes form independent of the microsphere surface. Once the complexes form, they are exposed to an excitation wavelength light source suitable for exciting the target ion to emit a luminescent signal pattern. Detection of the luminescent signal pattern allows for determination of the presence of the target ions in the sample.

  19. Optically Levitated Microspheres as a Probe for New Interactions

    NASA Astrophysics Data System (ADS)

    Rider, Alexander; Moore, David; Blakemore, Charles; Lu, Marie; Gratta, Giorgio

    2016-03-01

    We are developing novel techniques to probe new interactions at micron distances using optically levitated dielectric microspheres. Levitated microspheres are an ideal probe for short-range interactions because they are suspended using the radiation pressure at the focus of a laser beam, which means that the microspheres can be precisely manipulated and isolated from the surrounding environment at high vacuum. We have performed a search for unknown charged particles bound within the bulk of the microspheres. Currently, we are searching for the presence of a Chameleon field postulated to explain the presence of dark energy in the universe. In the future we plan to use optically levitated microspheres to search for micron length-scale gravity like interactions that could couple between a microsphere and another mass. We will present resent results from these experiments and plans for future searches for new interactions.

  20. Laser-assisted fabrication of highly viscous alginate microsphere

    NASA Astrophysics Data System (ADS)

    Lin, Yafu; Huang, Yong

    2011-04-01

    Encapsulated microspheres have been widely used in various biomedical applications. However, fabrication of encapsulated microspheres from highly viscous materials has always been a manufacturing challenge. The objective of this study is to explore a novel metallic foil-assisted laser-induced forward transfer (LIFT), a laser-assisted fabrication technique, to make encapsulated microspheres using high sodium alginate concentration solutions. The proposed four-layer approach includes a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a transferred suspension layer. It is found that the proposed four-layer modified LIFT approach provides a promising fabrication technology for making of bead-encapsulated microspheres from highly viscous solutions. During the process, the microsphere only can be formed if the direct-writing height is larger than the critical direct-writing height; otherwise, tail structured droplets are formed; and the encapsulated microsphere diameter linearly increases with the laser fluence and decreases with the sodium alginate concentration.

  1. Effect of vitamin E on cerebral cortical oxidative stress and brain-derived neurotrophic factor gene expression induced by hypoxia and exercise in rats.

    PubMed

    Sakr, H F; Abbas, A M; El Samanoudy, A Z

    2015-04-01

    Brain-derived neurotrophic factor (BDNF) is involved in the proliferation of neurons, and its expression increases significantly with exercise. We aimed to investigate the effects of chronic exercise (swimming) and sustained hypoxia on cortical BDNF expression in both the presence and absence of vitamin E. Sixty four male Sprague-Dawley rats were divided into two equal groups; a normoxic group and a hypoxic group. Both groups were equally subdivided into four subgroups: sedentary, sedentary with vitamin E, chronic exercise either with or without vitamin E supplementation. Arterial PO(2), and the levels of cortical malondialdehyde (MDA), antioxidants (reduced glutathione GSH, superoxide dismutase (SOD), catalase (CAT) and vitamin E) and BDNF gene expression were investigated. Hypoxia significantly increased MDA production and BDNF gene expression and decreased the antioxidants compared to control rats. Chronic exercise in hypoxic and normoxic rats increased MDA level and BDNF gene expression and decreased the antioxidants. Providing vitamin E supplementation to the hypoxic and normoxic rats significantly reduced MDA and BDNF gene expression and increased antioxidants. We conclude that sustained hypoxia and chronic exercise increased BDNF gene expression and induced oxidative stress. Moreover, vitamin E attenuated the oxidative stress and decreased BDNF gene expression in sustained hypoxia and chronic exercise which confirms the oxidative stress-induced stimulation of BDNF gene expression.

  2. Beat frequency ultrasonic microsphere contrast agent detection system

    NASA Technical Reports Server (NTRS)

    Pretlow, III, Robert A. (Inventor); Yost, William T. (Inventor); Cantrell, Jr., John H. (Inventor)

    1997-01-01

    A system for and method of detecting and measuring concentrations of an ultrasonically-reflective microsphere contrast agent involving detecting non-linear sum and difference beat frequencies produced by the microspheres when two impinging signals with non-identical frequencies are combined by mixing. These beat frequencies can be used for a variety of applications such as detecting the presence of and measuring the flow rates of biological fluids and industrial liquids, including determining the concentration level of microspheres in the myocardium.

  3. (D, L) polylactide microspheres as embolic agent. A preliminary study.

    PubMed

    Flandroy, P; Grandfils, C; Collignon, J; Thibaut, A; Nihant, N; Barbette, S; Jerome, R; Teyssie, P

    1990-01-01

    Owing to their shape, accurately calibrated microspheres appear to be very suitable material for distal embolization. Moreover, the biocompatible (D, L) polyactide (PLA) microspheres possess two other valuable advantages: easy adjustment of their biodegradation rate, and incorporation of chemotherapeutic agents during their production. The authors describe the preparation of these (D, L) PLA microspheres and their clinical applications as a preliminary step to arterial chemoembolization. PMID:2234391

  4. The Effect of Donor-Dependent Administration of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells following Focal Cerebral Ischemia in Rats.

    PubMed

    Park, Hyung Woo; Chang, Jong Wook; Yang, Yoon Sun; Oh, Wonil; Hwang, Jae Ha; Kim, Dong Gyu; Paek, Sun Ha

    2015-12-01

    Stroke is an ischemic disease caused by clotted vessel-induced cell damage. It is characterized by high morbidity and mortality and is typically treated with a tissue plasminogen activator (tPA). However, this therapy is limited by temporal constraints. Recently, several studies have focused on cell therapy as an alternative treatment. Most researches have used fixed donor cell administration, and hence, the effect of donor-dependent cell administration is unknown. In this study, we administered 3 types of donor-derived human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) in the ischemic boundary zone of the ischemic stroke rat model. We then performed functional and pathological characterization using rotarod, the limb placement test, and immunofluorescent staining. We observed a significant decrease in neuron number, and notable stroke-like motor dysfunction, as assessed by the rotarod test (~40% decrease in time) and the limb placement test (4.5 point increase) in control rats with ischemic stroke. The neurobehavioral performance of the rats with ischemic stroke that were treated with hUCB-MSCs was significantly better than that of rats in the vehicle-injected control group. Regardless of which donor cells were used, hUCB-MSC transplantation resulted in an accumulation of neuronal progenitor cells, and angiogenic and tissue repair factors in the ischemic boundary zone. The neurogenic and angiogenic profiles of the 3 types of hUCB-MSCs were very similar. Our results suggest that intraparenchymal administration of hUCB-MSCs results in significant therapeutic effects in the ischemic brain regardless of the type of donor. PMID:26713083

  5. Determining the size and refractive index of microspheres using the mode assignments from Mie resonances.

    PubMed

    Preston, Thomas C; Reid, Jonathan P

    2015-11-01

    A new method for determining the radius and refractive index of microspheres using Mie resonances is presented. Previous methods have relied on searching multidimensional space to find the radius and refractive index that minimize the difference between observed and calculated Mie resonances. For anything but simple refractive index functions, this process can be very time consuming. Here, we demonstrate that once the mode assignment for the observed Mie resonances is known, no search is necessary, and the radius and refractive index of best-fit can be found immediately. This superior and faster way to characterize microspheres using Mie resonances should supplant previous fitting algorithms. The derivation and implementation of the equations that give the parameters of best-fit are shown and discussed. Testing is performed on systems of physical interest, and the effect of noise on measured peak positions is investigated.

  6. Preparation of uniform magnetic recoverable catalyst microspheres with hierarchically mesoporous structure by using porous polymer microsphere template

    PubMed Central

    2014-01-01

    Merging nanoparticles with different functions into a single microsphere can exhibit profound impact on various applications. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated a facile method to incorporate magnetic nanoparticles into porous silica microspheres. Here, we report the fabrication of porous silica microspheres embedded with magnetic and gold nanoparticles as magnetic recoverable catalysts. The as-prepared multifunctional composite microspheres exhibit excellent magnetic and catalytic properties and a well-defined structure such as uniform size, high surface area, and large pore volume. As a result, the very little composite microspheres show high performance in catalytic reduction of 4-nitrophenol, special convenient magnetic separability, long life, and good reusability. The unique nanostructure makes the microspheres a novel stable and highly efficient catalyst system for various catalytic industry processes. PMID:24708885

  7. Preparation of porous zirconia microspheres by internal gelation method

    SciTech Connect

    Pathak, Sachin S.; Pius, I.C. Bhanushali, R.D.; Rao, T.V. Vittal; Mukerjee, S.K.

    2008-11-03

    A modified internal gelation process for the preparation of porous zirconia microspheres has been developed. The conventional method has been modified by adding a surfactant in the feed broth. The effects of variation of surfactant concentration, washing techniques and temperature of calcination on the pore volume and the surface area of the microspheres have been studied. The conditions were optimized to obtain porous stable microspheres suitable for various applications. The microspheres were characterized by surface area analysis, pore volume analysis, thermogravimetric analysis and X-ray diffraction. The ion exchange behavior was studied using pH titration.

  8. Fluorescent Microspheres as Point Sources: A Localization Study.

    PubMed

    Chao, Jerry; Lee, Taiyoon; Ward, E Sally; Ober, Raimund J

    2015-01-01

    The localization of fluorescent microspheres is often employed for drift correction and image registration in single molecule microscopy, and is commonly carried out by fitting a point spread function to the image of the given microsphere. The mismatch between the point spread function and the image of the microsphere, however, calls into question the suitability of this localization approach. To investigate this issue, we subject both simulated and experimental microsphere image data to a maximum likelihood estimator that localizes a microsphere by fitting an Airy pattern to its image, and assess the suitability of the approach by evaluating the ability of the estimator to recover the true location of the microsphere with the best possible accuracy as determined based on the Cramér-Rao lower bound. Assessing against criteria based on the standard errors of the mean and the variance for an ideal estimator of the microsphere's location, we find that microspheres up to 100 nm in diameter can in general be localized using a fixed width Airy pattern, and that microspheres as large as 1 μm in diameter can in general be localized using a floated width Airy pattern. PMID:26218251

  9. Chitosan microspheres as a delivery system for nasal insufflation.

    PubMed

    Patil, Sanjay B; Sawant, Krutika K

    2011-06-01

    The aim of the present study was to develop and characterize chitosan mucoadhesive microspheres for nasal delivery. The microspheres were prepared by emulsification-crosslinking method and evaluated for morphology, particle size, swelling index, in vitro mucoadhesion and delivery properties from Miat(®) nasal insufflator. The results showed that the microspheres were spherical in shape with smooth surfaces. The particle size of microspheres was found to be dependent on the concentration of the chitosan. The mean particle size was significantly increased when high concentration of chitosan was used. Aqueous to oil phase ratio, stirring rate and dioctyl sodium sulfosuccinate (DOSS) concentration also influenced the particle size distribution of the microspheres. It was found that, as stirring rate was increased, the size of the microspheres was decreased. The volume of glutaraldehyde and crosslinking time had very slight effect on particle size distribution. The % equilibrium water uptake of the microspheres was ranged from 124% to 232% and the mucoadhesive strength from 70.64±2.14 to 86.32±3.96%. The results of powder delivery from the device showed that, almost entire amount was delivered after three puffs. The images of the delivery sequences of microsphere powder clouds demonstrated that microspheres were delivered forming an elongated puff. The core of the clouds was homogeneous which can be expected to provide effective distribution pattern.

  10. Patterning of silica microsphere monolayers with focused femtosecond laser pulses

    SciTech Connect

    Cai Wenjian; Piestun, Rafael

    2006-03-13

    We demonstrate the patterning of monolayer silica microsphere lattices with tightly focused femtosecond laser pulses. We selectively removed microspheres from a lattice and characterized the effect on the lattice and the substrate. The proposed physical mechanism for the patterning process is laser-induced breakdown followed by ablation of material. We show that a microsphere focuses radiation in its interior and in the near field. This effect plays an important role in the patterning process by enhancing resolution and accuracy and by reducing the pulse energy threshold for damage. Microsphere patterning could create controlled defects within self-assembled opal photonic crystals.

  11. The xanthene dyes doped PMMA microspheres for optical sensor applications

    NASA Astrophysics Data System (ADS)

    Miluski, Piotr; Dorosz, Dominik; Kochanowicz, Marcin; Zmojda, Jacek; Dorosz, Jan

    2015-12-01

    The numerous applications of luminescent glass and polymeric microspheres are well known. The polymeric structures are popular as they assure good processability (solid and porous structures) and high doping level. The article presents the suspension polymerization process of polymeric (PMMA) microspheres doped by xanthene dyes: Fluorescein (Fl) and Rhodamine B (RhB). The bright luminescence at wavelengths 510nm 595nm respectively was recorded. The shape and dimension distributions of fabricated microspheres were optically determined. The article presents also potential applications of fabricated luminescent microspheres.

  12. Fiber optic chemical microsensors employing optically active silica microspheres

    NASA Astrophysics Data System (ADS)

    Pope, Edward J. A.

    1995-05-01

    Dye-doped porous silica microspheres can be prepared from liquid solution at temperatures near ambient. Microsphere diameter can be controlled between approximately 5.0 microns to in excess of a millimeter. The resulting microspheres can be attached to the distal end of an optical fiber in which the proximal end is attached to a spectrophotometer. Depending upon the organic species doped into the microsphere, a wide variety of sensing functions are possible. In this paper, the use of microsensors for measuring pH, temperature, and solvent content of aqueous solutions is demonstrated. Potential utility of this type of sensor to heavy metals detection and biomedical diagnostics is also discussed.

  13. Adrenergic receptor subtypes in the cerebral circulation of newborn piglets

    SciTech Connect

    Wagerle, L.C.; Delivoria-Papadopoulos, M.

    1987-06-01

    The purpose of this study was to identify the ..cap alpha..-adrenergic receptor subtype mediating cerebral vasoconstriction during sympathetic nerve stimulation in the newborn piglet. The effect of ..cap alpha../sub 1/- and ..cap alpha../sub 2/-antagonists prazosin and yohimbine on the cerebrovascular response to unilateral electrical stimulation (15 Hz, 15 V) of the superior cervical sympathetic trunk was studied in 25 newborn piglets. Regional cerebral blood flow was measured with tracer microspheres. Sympathetic stimulation decreased blood flow to the ipsilateral cerebrum hippocampus, choroid plexus, and masseter muscle. ..cap alpha../sub 1/-Adrenergic receptor blockade with prazosin inhibited the sympathetic vasoconstriction in the cerebrum, hippocampus, and masseter muscle and abolished it in the choroid plexus. ..cap alpha../sub s/-Adrenergic receptor blockade with yohimbine had no effect. Following the higher dose of yohimbine, however, blood flow to all brain regions was increased by approximately two-fold, possibly due to enhanced cerebral metabolism. These data demonstrate that vascular ..cap alpha../sub 1/-adrenergic receptors mediate vasoconstriction to neuroadrenergic stimulation in cerebral resistance vessels in the newborn piglet.

  14. Determination of cerebral cortical blood flow: a thermal technique.

    PubMed

    Hoehner, P J; Krause, G S; White, B C; Gadzinski, D S

    1983-01-01

    A mathematical model for tissue thermodilution was developed to study cerebral cortical perfusion before and after controlled perfusion arrest. Cerebral cortical perfusion rates are readily determined by this method. A thermistor was introduced into the subdural space and secured in direct contact with the frontal cortex in 12 dogs on ketamine and gallamine anesthesia. A 22-gauge angiocath was placed in the right superior thyroid artery and directed into the carotid artery on the same side as the thermistor. The dogs were placed on cardiac bypass using a circuit from the right atrium to the pulmonary artery and a second circuit from the left ventricular apex to the left femoral artery. Arterial pressure, central venous pressure (CVP), intracranial pressure (ICP), and left atrial pressure (LAP) were monitored directly. A heat exchanger was used to maintain a constant blood temperature of 37 C in the output of the left side bypass circuit. Thermal flow curves were generated in the cerebral cortex by injecting 2 to 4 cc of cold saline into the common carotid artery through the injection catheter. Preliminary evaluation of this flow method in comparison to radioactive microspheres indicates that this method can be used in a reliable and reproducible fashion to determine cerebral cortical blood flow.

  15. Demonstrating patency of STA-MCA anastomosis with Tc-99m albumin microspheres

    SciTech Connect

    Etani, H.; Kimura, K.; Yoneda, S.; Tsuda, Y.; Nakamura, M.; Kataoka, K.; Iwata, Y.; Abe, H.

    1983-02-01

    A patient with occlusion of the left internal carotid artery underwent an anastomosis between branches of the left superficial temporal and middle cerebral arteries (STA-MCA). A left carotid angiogram 9 days later showed extreme, tapered narrowing of the involved STA branch, with no filling of the MCA from the bypass. A year later, symptoms had improved slightly, and a minimally invasive study was made with Tc-99m human albumin microspheres. This showed patency of the bypass, with intracranial perfusion in the MCA field, findings later confirmed by a repeat left carotid angiogram. It appears that Tc-99m HAM scintigraphy will be useful in assessing the effectiveness of this and other bypass operations.

  16. Demonstrating patency of STA-MCA anastomosis with /sup 99m/Tc albumin microspheres

    SciTech Connect

    Etani, H.; Kimura, K.; Yoneda, S.; Tsuda, Y.; Nakamura, M.; Kataoka, K.; Iwata, Y.; Abe, H.

    1983-02-01

    A patient with occlusion of the left internal carotid artery underwent an anastomosis between branches of the left superficial temporal and middle cerebral arteries (STA-MCA). A left carotid angiogram 9 days later showed extreme, tapered narrowing of the involved STA branch, with no filling of the MCA from the bypass. A year later, symptoms had improved slightly, and a minimally invasive study was made with /sup 99m/Tc human albumin microspheres. This showed patency of the bypass, with intracranial perfusion in the MCA field, findings later confirmed by a repeat left carotid angiogram. It appears that /sup 99m/Tc HAM scintigraphy will be useful in assessing the effectiveness of this and other bypass operations.

  17. Cell specific, variable density, polymer microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1978-01-01

    Biocompatible polymeric microspheres having an average diameter below about 3 microns and having a density at least 15% greater or lesser than organic cells and having covalent binding sites are provided in accordance with this invention. The microspheres are obtained by copolymerizing a hydroxy or amine substituted acrylic monomer such as hydroxyethylmethacrylate with a light or dense comonomer such as a fluoromonomer. A lectin or antibody is bound to the hydroxy or amine site of the bead to provide cell specificity. When added to a cell suspension the marked bead will specifically label the cell membrane by binding to specific receptor sites thereon. The labelled membrane can then be separated by density gradient centrifugation.

  18. Fluorescence dynamics of microsphere-adsorbed sunscreens

    NASA Astrophysics Data System (ADS)

    Krishnan, R.

    2005-03-01

    Sunscreens are generally oily substances which are prepared in organic solvents, emulsions or dispersions with micro- or nanoparticles. These molecules adsorb to and integrate into skin cells. In order to understand the photophysical properties of the sunscreen, we compare steady-state and time-resolved fluorescence in organic solvent of varying dielectric constant ɛ and adsorbed to polystyrene microspheres and dispersed in water. Steady-state fluorescence is highest and average fluorescence lifetime longest in toluene, the solvent of lowest ɛ. However, there is no uniform dependence on ɛ. Sunscreens PABA and padimate-O show complex emission spectra. Microsphere-adsorbed sunscreens exhibit highly non-exponential decay, illustrative of multiple environments of the adsorbed molecule. The heterogeneous fluorescence dynamics likely characterizes sunscreen adsorbed to cells.

  19. Neutron transmission measurements on hydrogen filled microspheres

    NASA Astrophysics Data System (ADS)

    Dyrnjaja, Eva; Hummel, Stefan; Keding, Marcus; Smolle, Marie-Theres; Gerger, Joachim; Zawisky, Michael

    2014-01-01

    Hollow microspheres are promising candidates for future hydrogen storage technologies. Although the physical process for hydrogen diffusion through glass is well understood, measurements of static quantities (e.q. hydrogen pressure inside the spheres) as well as dynamic properties (e.g. diffusion rate of hydrogen through glass) are still difficult to handle due to the small size of the spheres (d≈15μm). For diffusion rate measurements, the long-term stability of the experiment is also mandatory due to the relatively slow diffusion rate. In this work, we present an accurate and long-term stable measurement technique for static and dynamic properties, using neutron radiography. Furthermore, possible applications for hydrogen filled microspheres within the scope of radiation issues are discussed.

  20. Sputter coating of microspherical substrates by levitation

    DOEpatents

    Lowe, A.T.; Hosford, C.D.

    Microspheres are substantially uniformly coated with metals or nonmetals by simltaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure comprising a parallel array of upwardly projecting individual gas outlets is machined out to form a dimple. Glass microballoons,, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  1. Sputter coating of microspherical substrates by levitation

    DOEpatents

    Lowe, Arthur T.; Hosford, Charles D.

    1981-01-01

    Microspheres are substantially uniformly coated with metals or nonmetals by simultaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure 12 comprising a parallel array of upwardly projecting individual gas outlets 16 is machined out to form a dimple 11. Glass microballoons, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  2. Optimization of sustained release aceclofenac microspheres using response surface methodology.

    PubMed

    Deshmukh, Rameshwar K; Naik, Jitendra B

    2015-03-01

    Polymeric microspheres containing aceclofenac were prepared by single emulsion (oil-in-water) solvent evaporation method using response surface methodology (RSM). Microspheres were prepared by changing formulation variables such as the amount of Eudragit® RS100 and the amount of polyvinyl alcohol (PVA) by statistical experimental design in order to enhance the encapsulation efficiency (E.E.) of the microspheres. The resultant microspheres were evaluated for their size, morphology, E.E., and in vitro drug release. The amount of Eudragit® RS100 and the amount of PVA were found to be significant factors respectively for determining the E.E. of the microspheres. A linear mathematical model equation fitted to the data was used to predict the E.E. in the optimal region. Optimized formulation of microspheres was prepared using optimal process variables setting in order to evaluate the optimization capability of the models generated according to IV-optimal design. The microspheres showed high E.E. (74.14±0.015% to 85.34±0.011%) and suitably sustained drug release (minimum; 40% to 60%; maximum) over a period of 12h. The optimized microspheres formulation showed E.E. of 84.87±0.005 with small error value (1.39). The low magnitudes of error and the significant value of R(2) in the present investigation prove the high prognostic ability of the design. The absence of interactions between drug and polymers was confirmed by Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) revealed the dispersion of drug within microspheres formulation. The microspheres were found to be discrete, spherical with smooth surface. The results demonstrate that these microspheres could be promising delivery system to sustain the drug release and improve the E.E. thus prolong drug action and achieve the highest healing effect with minimal gastrointestinal side effects.

  3. Pulmonary toxicity of Expancel microspheres in the rat.

    PubMed

    Porter, Dale W; Hubbs, Ann F; Baron, Paul A; Millecchia, Lyndell L; Wolfarth, Michael G; Battelli, Lori A; Schwegler-Berry, Diane E; Beighley, Christopher M; Andrew, Michael E; Castranova, Vincent

    2007-08-01

    Expancel microspheres are thermoplastic microspheres enclosing hydrocarbon. These microspheres expand when heated, producing many applications. Because they have unknown biological persistence and toxicity, we investigated the toxicity of two unexpanded (11.1 and 15.4 micro m mean diameter) and two expanded (3.1 and 5.5 micro m mass median aerodynamic diameter) Expancel microspheres in intratracheally-instilled, male, Sprague-Dawley rats. Pulmonary histopathology was evaluated at 28 days postexposure. Bronchoalveolar lavage fluid was evaluated at days 1, 7, 14, and 28 days postexposure. Crystalline silica was the positive control. By histopathology, both unexpanded and expanded microspheres caused granulomatous bronchopneumonia characterized by macrophages and giants cells, suggesting a persistent foreign body response. Expanded, but not unexpanded microspheres, also caused eosinophilic bronchitis and bronchiolitis, mucous metaplasia of airways and organized granulomatous inflammation with associated fibrosis and frequent airway obstruction. In contrast, alveolar macrophage activation, polymorphonuclear leukocytes, LDH and albumin in bronchoalveolar laveage fluid were initially elevated but returned to near control levels at 28 days, and did not reflect the persistent granulomatous bronchopneumonia caused by Expancel microspheres. These findings emphasize the importance of histopathology for evaluating pulmonary toxicity, suggest that Expancel microspheres are a potential occupational hazard, and indicate a need for additional studies on their potential pulmonary toxicity. [Supplementary materials are available for this article. Go to the publisher's online edition of Toxicology Pathology for the following free supplemental resources: motion within unexpected microspheres in H&E-stained lung (supplementary Figure 1); broncholar epithelium 28 days following exposure to 551 DE 20 microspheres (supplementary Figure 2); membrane ruffling and some instances of

  4. Statins and cerebral hemodynamics

    PubMed Central

    Giannopoulos, Sotirios; Katsanos, Aristeidis H; Tsivgoulis, Georgios; Marshall, Randolph S

    2012-01-01

    HMG-CoA reductase inhibitors (statins) are associated with improved stroke outcome. This observation has been attributed in part to the palliative effect of statins on cerebral hemodynamics and cerebral autoregulation (CA), which are mediated mainly through the upregulation of endothelium nitric oxide synthase (eNOS). Several animal studies indicate that statin pretreatment enhances cerebral blood flow after ischemic stroke, although this finding is not further supported in clinical settings. Cerebral vasomotor reactivity, however, is significantly improved after long-term statin administration in most patients with severe small vessel disease, aneurysmal subarachnoid hemorrhage, or impaired baseline CA. PMID:22929438

  5. Role of hypotension in decreasing cerebral blood flow in porcine endotoxemia

    SciTech Connect

    Miller, C.F.; Breslow, M.J.; Shapiro, R.M.; Traystman, R.J. )

    1987-10-01

    The role of reduced arterial blood pressure (MAP) in decreasing cerebral blood flow (CBF) during endotoxemia was studied in pentobarbital-anesthetized pigs. Microspheres were used to measure regional CBF changes during MAP manipulations in animals with and without endotoxin. Endotoxin decreased MAP to 50 mmHg and decreased blood flow to the cortex and cerebellum without affecting cerebral cortical oxygen consumption (CMRo{sub 2}). Elevating MAP from 50 to 70 mmHg during endotoxemia with norepinephrine did not change cortical blood flow or CMRo{sub 2} but increased cerebellar blood flow. Brain stem blood flow was not affected by endotoxin or norepinephrine. When MAP was decreased to 50 mmHg by hemorrhage without endotoxin, no change in blood flow to cortex, cerebellum, or brain stem was observed from base-line levels. These results suggest that decreased MAP below a lower limit for cerebral autoregulation does not account for the decreased CBF observed after endotoxin.

  6. Cerebral Asymmetries and Reading Acquisition

    ERIC Educational Resources Information Center

    Pirozzolo, Francis J.

    1978-01-01

    Reviewed are historical developments regarding the concepts of cerebral localization, and analyzed are implications of current research on the role of the cerebral hemispheres in reading disorders. (CL)

  7. Mucoadhesive Microspheres Containing Amoxicillin for Clearance of Helicobacter pylori

    PubMed Central

    Nagahara, Naoki; Akiyama, Yohko; Nakao, Masafumi; Tada, Mayumi; Kitano, Megumi; Ogawa, Yasuyuki

    1998-01-01

    In an effort to augment the anti-Helicobacter pylori effect of amoxicillin, mucoadhesive microspheres, which have the ability to reside in the gastrointestinal tract for an extended period, were prepared. The microspheres contained the antimicrobial agent and an adhesive polymer (carboxyvinyl polymer) powder dispersed in waxy hydrogenated castor oil. The percentage of amoxicillin remaining in the stomach both 2 and 4 h after oral administration of the mucoadhesive microspheres to Mongolian gerbils under fed conditions was about three times higher than that after administration in the form of a 0.5% methylcellulose suspension. The in vivo clearance of H. pylori following oral administration of the mucoadhesive microspheres and the 0.5% methylcellulose suspension to infected Mongolian gerbils was examined under fed conditions. The mucoadhesive microspheres and the 0.5% methylcellulose suspension both showed anti-H. pylori effects in this experimental model of infection, but the required dose of amoxicillin was effectively reduced by a factor of 10 when the mucoadhesive microspheres were used. In conclusion, the mucoadhesive microspheres more effectively cleared H. pylori from the gastrointestinal tract than the 0.5% methylcellulose suspension due to the prolonged gastrointestinal residence time resulting from mucoadhesion. A dosage form consisting of mucoadhesive microspheres containing an appropriate antimicrobial agent should be useful for the eradication of H. pylori. PMID:9756746

  8. Coacervate droplets, proteinoid microspheres, and the genetic apparatus

    NASA Technical Reports Server (NTRS)

    Fox, S. W.

    1974-01-01

    Differences between typical coacervate droplets and typical proteinoid microspheres are examined. It is pointed out that coacervate droplets are produced from polymers obtained from contemporary organisms. The microspheres considered are aggregates of proteinoid formed from monomeric amino acids under geologically relevant conditions. Aspects regarding the primordial sequence are discussed along with the origin of the genetic apparatus and the genetic code.

  9. Porous-wall hollow glass microspheres as carriers for biomolecules

    DOEpatents

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  10. Characterization of carbon cryogel microspheres as adsorbents for VOC.

    PubMed

    Yamamoto, Takuji; Kataoka, Sho; Ohmori, Takao

    2010-05-15

    Adsorption characteristics of carbon cryogel microspheres (CC microspheres) with controlled porous structure composed of mesopores (2 nmmicrospheres could be changed by varying either the size of the mesopores or the volume of the micropores. The peak temperature of the temperature-programmed desorption profiles of toluene from the CC microspheres was higher than that from granular activated carbon (GAC) with numerous micropores, indicating that toluene is adsorbed more strongly on CC microspheres than on GAC. To permit the practical use of CC microspheres, the adsorption characteristic of moisture on CC microspheres and GAC were evaluated. The effect of adsorption of moisture on the gas permeation property of an adsorption module prepared from the CC microspheres was also examined. PMID:20042276

  11. Fluorescent Microspheres as Point Sources: A Localization Study

    PubMed Central

    Chao, Jerry; Lee, Taiyoon; Ward, E. Sally; Ober, Raimund J.

    2015-01-01

    The localization of fluorescent microspheres is often employed for drift correction and image registration in single molecule microscopy, and is commonly carried out by fitting a point spread function to the image of the given microsphere. The mismatch between the point spread function and the image of the microsphere, however, calls into question the suitability of this localization approach. To investigate this issue, we subject both simulated and experimental microsphere image data to a maximum likelihood estimator that localizes a microsphere by fitting an Airy pattern to its image, and assess the suitability of the approach by evaluating the ability of the estimator to recover the true location of the microsphere with the best possible accuracy as determined based on the Cramér-Rao lower bound. Assessing against criteria based on the standard errors of the mean and the variance for an ideal estimator of the microsphere’s location, we find that microspheres up to 100 nm in diameter can in general be localized using a fixed width Airy pattern, and that microspheres as large as 1 μm in diameter can in general be localized using a floated width Airy pattern. PMID:26218251

  12. Pectin/zein microspheres as a sustained drug delivery system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of microspheres were prepared from pectins and corn proteins from various sources in the presence of the divalent ions calcium or zinc. The results showed that the yield of microsphere and the efficiency of drug incorporation were dependent on the type and ratio of biopolymers, the size of ...

  13. Surface Wrinkling on Polydimethylsiloxane Microspheres via Wet Surface Chemical Oxidation

    PubMed Central

    Yin, Jian; Han, Xue; Cao, Yanping; Lu, Conghua

    2014-01-01

    Here we introduce a simple low-cost yet robust method to realize spontaneously wrinkled morphologies on spherical surfaces. It is based on surface chemical oxidation of aqueous-phase-synthesized polydimethylsiloxane (PDMS) microspheres in the mixed H2SO4/HNO3/H2O solution. Consequently, curvature and overstress-sensitive wrinkles including dimples and labyrinth patterns are successfully induced on the resulting oxidized PDMS microspheres. A power-law dependence of the wrinkling wavelength on the microsphere radius exists. The effects of experimental parameters on these tunable spherical wrinkles have been systematically investigated, when the microspheres are pre-deposited on a substrate. These parameters include the radius and modulus of microspheres, the mixed acid solution composition, the oxidation duration, and the water washing post-treatment. Meanwhile, the complicated chemical oxidation process has also been well studied by in-situ optical observation via the microsphere system, which represents an intractable issue in a planar system. Furthermore, we realize surface wrinkled topographies on the whole microspheres at a large scale, when microspheres are directly dispersed in the mixed acid solution for surface oxidation. These results indicate that the introduced wet surface chemical oxidation has the great potential to apply to other complicated curved surfaces for large-scale generation of well-defined wrinkling patterns, which endow the solids with desired physical properties. PMID:25028198

  14. Surface molecularly imprinted magnetic microspheres for the recognition of albumin.

    PubMed

    Kartal, Fatma; Denizli, Adil

    2014-08-01

    A new approach, combining metal coordination with the molecular imprinting technique, was developed to prepare affinity materials. Magnetic poly(glycidyl methacrylate) microspheres in monosize form were used for specific recognition toward the target protein. The magnetic poly(glycidyl methacrylate) microspheres were prepared by dispersion polymerization in the presence of magnetite nanopowder. Surface imprinted magnetic poly(glycidyl methacrylate) microspheres based on metal coordination were prepared and used for the selective recognition of human serum albumin. Iminodiacetic acid was used as the metal coordinating agent and human serum albumin was anchored by Cu(2+) ions on the surface of magnetic poly(glycidyl methacrylate) microspheres by metal coordination. The magnetic poly(glycidyl methacrylate) microspheres were coated with a polymer formed by condensation of tetraethyl orthosilicate and 3-aminopropyltrimethoxysilane. The human serum albumin imprinted magnetic poly(glycidyl methacrylate) microspheres were characterized by scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy and particle size analysis. The maximum adsorption capacity of human serum albumin imprinted magnetic poly(glycidyl methacrylate) microspheres was 37.7 mg/g polymer at pH 6.0. The selectivity experiments of human serum albumin imprinted magnetic poly(glycidyl methacrylate) microspheres prepared with different concentrations in the presence of lysozyme, bovine serum albumin and cytochrome C were performed in order to determine the relative selectivity coefficients.

  15. Rapid biomimetic mineralization of hydroxyapatite-g-PDLLA hybrid microspheres.

    PubMed

    Du, Ke; Shi, Xudong; Gan, Zhihua

    2013-12-10

    Hydroxyapatite-graft-poly(D,L-lactide) (HA-g-PDLLA) nanoparticles were synthesized here to fabricate hybrid microspheres with diameter in the range of 150-200 μm by emulsion solvent evaporation techniques. The as-obtained microspheres were treated with alkaline solution in order to selectively degrade the PDLLA layer which covered on the surface of hybrid microspheres and instead to generate a dense coating of HA nanoparticles. The hybrid microspheres with enriched HA nanoparticles on the surface were further immersed in simulated body fluid (SBF) solution to evaluate the bone-forming ability of the bioactive hybrid microspheres via the in vitro biomimetic mineralization process. The resultant microspheres were analyzed by using X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to understand the nucleation and growth of bioactive calcium phosphate (Ca-P) crystals as a function of surface treatment. Results in this work clearly demonstrated that the existing HA nanoparticles on the surface of hybrid microspheres after alkaline treatment greatly affect the growth of the bone-like Ca-P crystals in SBF solutions. The biomimetic hybrid microspheres were found to be excellent candidates for use as injectable scaffolds for bone tissue engineering.

  16. Surface Wrinkling on Polydimethylsiloxane Microspheres via Wet Surface Chemical Oxidation

    NASA Astrophysics Data System (ADS)

    Yin, Jian; Han, Xue; Cao, Yanping; Lu, Conghua

    2014-07-01

    Here we introduce a simple low-cost yet robust method to realize spontaneously wrinkled morphologies on spherical surfaces. It is based on surface chemical oxidation of aqueous-phase-synthesized polydimethylsiloxane (PDMS) microspheres in the mixed H2SO4/HNO3/H2O solution. Consequently, curvature and overstress-sensitive wrinkles including dimples and labyrinth patterns are successfully induced on the resulting oxidized PDMS microspheres. A power-law dependence of the wrinkling wavelength on the microsphere radius exists. The effects of experimental parameters on these tunable spherical wrinkles have been systematically investigated, when the microspheres are pre-deposited on a substrate. These parameters include the radius and modulus of microspheres, the mixed acid solution composition, the oxidation duration, and the water washing post-treatment. Meanwhile, the complicated chemical oxidation process has also been well studied by in-situ optical observation via the microsphere system, which represents an intractable issue in a planar system. Furthermore, we realize surface wrinkled topographies on the whole microspheres at a large scale, when microspheres are directly dispersed in the mixed acid solution for surface oxidation. These results indicate that the introduced wet surface chemical oxidation has the great potential to apply to other complicated curved surfaces for large-scale generation of well-defined wrinkling patterns, which endow the solids with desired physical properties.

  17. β-Cyclodextrin-based oil-absorbent microspheres: preparation and high oil absorbency.

    PubMed

    Song, Ci; Ding, Lei; Yao, Fei; Deng, Jianping; Yang, Wantai

    2013-01-01

    This article reports the preparation and evaluation of polymeric microspheres as a new class of oil-absorbent (POAMs). Based on our earlier oil-absorbents, the present microspheres contained β-cyclodextrin (β-CD) moieties as both cross-linking agent and porogen agent, and showed exciting high oil absorbency, fast oil absorption speed and good reusability. Such microspheres were prepared via suspension polymerization with octadecyl acrylate and butyl acrylate as co-monomers, β-CD derivative as cross-linking agent, 2,2'-azoisobutyronitrile as initiator and polyvinylalcohol as stabilizer. Oil absorbency of the POAMs was, for CCl(4), 83.4; CHCl(3), 75.1; xylene, 48.7; toluene, 42.8; gasoline, 30.0; kerosene 27.1; and diesel, 18.2 g/g (oil/POAMs). Saturation oil absorption reached within 3h in CCl(4). The POAMs exhibited high oil retention percentage (>90%), and can be reused for at least 10 times while keeping oil absorbency almost unchanged. PMID:23044125

  18. Resolution enhancement phase-contrast imaging by microsphere digital holography

    NASA Astrophysics Data System (ADS)

    Wang, Yunxin; Guo, Sha; Wang, Dayong; Lin, Qiaowen; Rong, Lu; Zhao, Jie

    2016-05-01

    Microsphere has shown the superiority of super-resolution imaging in the traditional 2D intensity microscope. Here a microsphere digital holography approach is presented to realize the resolution enhancement phase-contrast imaging. The system is designed by combining the microsphere with the image-plane digital holography. A microsphere very close to the object can increase the resolution by transforming the object wave from the higher frequency to the lower one. The resolution enhancement amplitude and phase images can be retrieved from a single hologram. The experiments are carried on the 1D and 2D gratings, and the results demonstrate that the observed resolution has been improved, meanwhile, the phase-contrast image is obtained. The proposed method can improve the transverse resolution in all directions based on a single exposure. Furthermore, this system has extended the application of the microsphere from the conventional 2D microscopic imaging to 3D phase-contrast microscopic imaging.

  19. Hollow porous-wall glass microspheres for hydrogen storage

    DOEpatents

    Heung, Leung K.; Schumacher, Ray F.; Wicks, George G.

    2010-02-23

    A porous wall hollow glass microsphere is provided having a diameter range of between 1 to 200 microns, a density of between 1.0 to 2.0 gm/cc, a porous-wall structure having wall openings defining an average pore size of between 10 to 1000 angstroms, and which contains therein a hydrogen storage material. The porous-wall structure facilitates the introduction of a hydrogen storage material into the interior of the porous wall hollow glass microsphere. In this manner, the resulting hollow glass microsphere can provide a membrane for the selective transport of hydrogen through the porous walls of the microsphere, the small pore size preventing gaseous or liquid contaminants from entering the interior of the hollow glass microsphere.

  20. Optical cavity modes of a single crystalline zinc oxide microsphere.

    PubMed

    Moirangthem, Rakesh Singh; Cheng, Pi-Ju; Chien, Paul Ching-Hang; Ngo, Buu Trong Huynh; Chang, Shu-Wei; Tien, Chung-Hao; Chang, Yia-Chung

    2013-02-11

    A detailed study on the optical cavity modes of zinc oxide microspheres under the optical excitation is presented. The zinc oxide microspheres with diameters ranging from 1.5 to 3.0 µm are prepared using hydrothermal growth technique. The photoluminescence measurement of a single microsphere shows prominent resonances of whispering gallery modes at room temperature. The experimentally observed whispering gallery modes in the photoluminescence spectrum are compared with theoretical calculations using analytical and finite element methods in order to clarify resonance properties of these modes. The comparison between theoretical analysis and experiment suggests that the dielectric constant of the ZnO microsphere is somewhat different from that for bulk ZnO. The sharp resonances of whispering gallery modes in zinc oxide microspheres cover the entire visible window. They may be utilized in realizations of optical resonators, light emitting devices, and lasers for future chip integrations with micro/nano optoelectronic circuits, and developments of optical biosensors. PMID:23481759

  1. Textiles with gallic acid microspheres: in vitro release characteristics.

    PubMed

    Martí, Meritxell; Martínez, Vanessa; Carreras, Núria; Alonso, Cristina; Lis, Manuel José; Parra, José Luis; Coderch, Luisa

    2014-01-01

    Abstract The aim of this study was to demonstrate the skin penetration of an antioxidant, gallic acid (GA), encapsulated in poly-ε-caprolactone (PCL) microspheres and applied onto textile fabrics, by a specific in vitro percutaneous absorption methodology. Two techniques (particle size distribution and FTIR) were used to characterise the microspheres obtained. The amount of GA-loaded microspheres present in the biofunctional textiles was established before their use as a textile drug delivery system. More absorption and desorption of microspheres with GA for the polyamide fabric were found in comparison with cotton fabric. The percutaneous absorption results indicated that the skin penetration of GA released from PCL-microspheres that were applied directly to the skin was higher than when GA was embedded within biofunctional textiles, in conclusion, an interesting reservoir effect may be promoted when biofunctional textiles were used.

  2. Novel sustained release microspheres for pulmonary drug delivery.

    PubMed

    Cook, Robert O; Pannu, Rupi K; Kellaway, Ian W

    2005-05-01

    A novel process for generating sustained release (SR) particles for pulmonary drug delivery is described. High purity nanoparticles of a hydrophilic, ionised drug are entrapped within hydrophobic microspheres using a spray-drying approach. Sustained release of the model drug, terbutaline sulphate (TS), from the microspheres was found to be proportional to drug loading and phospholipid content. Microspheres with a 33% drug loading exhibited sustained release of 32.7% over 180 min in phosphate buffer. Release was not significantly different in simulated lung fluids. No significant burst release was observed which suggested that nanoparticles were coated effectively during spray-drying. The absence of nanoparticles at the microsphere surface was confirmed with confocal microscopy. The sustained release microspheres were formulated as a carrier-free dry powder for inhalation, and exhibited a favourable Fine Particle Fraction (FPF) of 46.5+/-1.8% and Mass Median Aerodynamic Diameter (MMAD) of 3.93+/-0.12 microm. PMID:15866336

  3. Synthesis and characterization of magnetic poly(glycidyl methacrylate) microspheres

    NASA Astrophysics Data System (ADS)

    Horák, Daniel; Petrovský, Eduard; Kapička, Aleš; Frederichs, Theodor

    2007-04-01

    Magnetic nanoparticles encapsulated in poly(glycidyl methacrylate) microspheres were prepared and their detailed structural and magnetic characteristics given. Iron oxide nanoparticles were obtained by chemical coprecipitation of Fe(II) and Fe(III) salts and stabilized with dextran, (carboxymethyl)dextran or tetramethylammonium hydroxide. The microspheres were prepared by emulsion or dispersion polymerization of glycidyl methacrylate in the presence of ferrofluid. The microspheres were uniform both in shape and usually also in size; their size distribution was narrow. All the magnetic parameters confirm superparamagnetic nature of the microspheres. Blocking temperature was not observed, suggesting the absence of magnetic interactions at low temperatures. This is most probably caused by complete encapsulation and the absence of agglomeration. Such microspheres can be used in biomedical applications.

  4. Cerebral oxygenation and haemodynamics in the foetus and newborn infant.

    PubMed Central

    Wyatt, J S

    1997-01-01

    Quantitative techniques have been derived for the measurement of global cerebral blood flow, cerebral blood volume, its response to changing arterial carbon dioxide tension and mixed cerebral venous saturation in the human newborn undergoing intensive care. Normal ranges have been established and significant disturbances of cerebral oxygenation and perfusion have been demonstrated in a variety of pathological conditions. Recently, absolute cerebral deoxyhaemoglobin concentration has been obtained in the newborn using second differential spectroscopy. When combined with the measurement of total cerebral haemoglobin concentration, the mean saturation of cerebral blood (SmcO2) may be obtained, allowing global cerebral oxygenation to be determined continuously in the intensive care unit. Marked changes in the concentrations of cerebral oxy- and deoxyhaemoglobin have been observed in foetuses undergoing labour. Measurements of SmcO2 from the foetal brain prior to delivery have shown the expected close correlation with acid-base status at birth. Although movement artefact remains a theoretical risk during uterine contractions, preliminary measurements of optical path length by intensity-modulated spectroscopy have demonstrated only small fluctuations. In future the clinical application of time, phase and spatially resolved spectroscopy is likely to improve both the quantitative accuracy and the regional specificity of physiological measurements in the foetal and neonatal brain. PMID:9232857

  5. Cerebral oxygenation and haemodynamics in the foetus and newborn infant.

    PubMed

    Wyatt, J S

    1997-06-29

    Quantitative techniques have been derived for the measurement of global cerebral blood flow, cerebral blood volume, its response to changing arterial carbon dioxide tension and mixed cerebral venous saturation in the human newborn undergoing intensive care. Normal ranges have been established and significant disturbances of cerebral oxygenation and perfusion have been demonstrated in a variety of pathological conditions. Recently, absolute cerebral deoxyhaemoglobin concentration has been obtained in the newborn using second differential spectroscopy. When combined with the measurement of total cerebral haemoglobin concentration, the mean saturation of cerebral blood (SmcO2) may be obtained, allowing global cerebral oxygenation to be determined continuously in the intensive care unit. Marked changes in the concentrations of cerebral oxy- and deoxyhaemoglobin have been observed in foetuses undergoing labour. Measurements of SmcO2 from the foetal brain prior to delivery have shown the expected close correlation with acid-base status at birth. Although movement artefact remains a theoretical risk during uterine contractions, preliminary measurements of optical path length by intensity-modulated spectroscopy have demonstrated only small fluctuations. In future the clinical application of time, phase and spatially resolved spectroscopy is likely to improve both the quantitative accuracy and the regional specificity of physiological measurements in the foetal and neonatal brain. PMID:9232857

  6. Microsphere-Based Scaffolds Carrying Opposing Gradients of Chondroitin Sulfate and Tricalcium Phosphate

    PubMed Central

    Gupta, Vineet; Mohan, Neethu; Berkland, Cory J.; Detamore, Michael S.

    2015-01-01

    Extracellular matrix (ECM) components, such as chondroitin sulfate (CS) and tricalcium phosphate, serve as raw materials, and thus spatial patterning of these raw materials may be leveraged to mimic the smooth transition of physical, chemical, and mechanical properties at the bone-cartilage interface. We hypothesized that encapsulation of opposing gradients of these raw materials in high molecular weight poly(d,l-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds would enhance differentiation of rat bone marrow–derived stromal cells. The raw material encapsulation altered the microstructure of the microspheres and also influenced the cellular morphology that depended on the type of material encapsulated. Moreover, the mechanical properties of the raw material encapsulating microsphere-based scaffolds initially relied on the composition of the scaffolds and later on were primarily governed by the degradation of the polymer phase and newly synthesized ECM by the seeded cells. Furthermore, raw materials had a mitogenic effect on the seeded cells and led to increased glycosaminoglycan (GAG), collagen, and calcium content. Interestingly, the initial effects of raw material encapsulation on a per-cell basis might have been overshadowed by medium-regulated environment that appeared to favor osteogenesis. However, it is to be noted that in vivo, differentiation of the cells would be governed by the surrounding native environment. Thus, the results of this study demonstrated the potential of the raw materials in facilitating neo-tissue synthesis in microsphere-based scaffolds and perhaps in combination with bioactive signals, these raw materials may be able to achieve intricate cell differentiation profiles required for regenerating the osteochondral interface. PMID:26191526

  7. Microsphere-Based Scaffolds Carrying Opposing Gradients of Chondroitin Sulfate and Tricalcium Phosphate.

    PubMed

    Gupta, Vineet; Mohan, Neethu; Berkland, Cory J; Detamore, Michael S

    2015-01-01

    Extracellular matrix (ECM) components, such as chondroitin sulfate (CS) and tricalcium phosphate, serve as raw materials, and thus spatial patterning of these raw materials may be leveraged to mimic the smooth transition of physical, chemical, and mechanical properties at the bone-cartilage interface. We hypothesized that encapsulation of opposing gradients of these raw materials in high molecular weight poly(d,l-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds would enhance differentiation of rat bone marrow-derived stromal cells. The raw material encapsulation altered the microstructure of the microspheres and also influenced the cellular morphology that depended on the type of material encapsulated. Moreover, the mechanical properties of the raw material encapsulating microsphere-based scaffolds initially relied on the composition of the scaffolds and later on were primarily governed by the degradation of the polymer phase and newly synthesized ECM by the seeded cells. Furthermore, raw materials had a mitogenic effect on the seeded cells and led to increased glycosaminoglycan (GAG), collagen, and calcium content. Interestingly, the initial effects of raw material encapsulation on a per-cell basis might have been overshadowed by medium-regulated environment that appeared to favor osteogenesis. However, it is to be noted that in vivo, differentiation of the cells would be governed by the surrounding native environment. Thus, the results of this study demonstrated the potential of the raw materials in facilitating neo-tissue synthesis in microsphere-based scaffolds and perhaps in combination with bioactive signals, these raw materials may be able to achieve intricate cell differentiation profiles required for regenerating the osteochondral interface. PMID:26191526

  8. [Cerebral blood flow, metabolism and learning after a cerebral infarction in the rat (author's transl)].

    PubMed

    Le Poncin-Lafitte, M; Grosdemouge, C; Roy-Billon, C; Duterte, D; Rapin, J R

    1981-01-01

    Experimental microembolization of the rat brain has been used as a model for the production of cerebral microinfarction which resulted in a decrease in blood flow and secondary brain edema with changes in the oxidative metabolic pathways. The use of radioactive microspheres as embolizing agents allowed to determine the number of microinfarctions and their localization. In every microinfarct, oedema developed and it could be quantified by measuring the water percentage as soon as the fourth hour following the microembolization. The activity of oxygen-dependent enzymes was severely reduced in the ischemic area around which hyperemia was present. A quick decrease in the ATP and glucose levels and an increase in the lactate levels were observed, showing that the energetic metabolism was deviated towards the anaerobic pathway. On the fifth day following the microembolization, the oedema disappeared. The cellular metabolic activity and the cerebral blood flow almost returned to normal values within the same time. The simultaneously study of an avoidance response in a conditioned learning test showed a correlation between the reappearance of this response and the regression of the oedema. PMID:6896095

  9. Cerebral Palsy (CP) Quiz

    MedlinePlus

    ... Submit Button Past Emails CDC Features Pop Quiz: Cerebral Palsy Language: English Español (Spanish) Recommend on Facebook Tweet ... Sandy is the parent of a child with cerebral palsy and the Board President of Gio’s Garden , a ...

  10. Hemihyperhidrosis in cerebral infarction.

    PubMed

    Faruqi, Shoaib; Redmond, Gemma; Ram, Pusbar; Owens, Val B; Sangster, Graeme; Barrett, James A

    2004-09-01

    Increased sweating on the hemiparetic side in cerebral infarcts is not a common clinical finding. The onset, severity and duration of symptoms can vary. The structural lesion responsible for this is a subject of conjecture. We present the case of a 66-year-old man who developed hemihyperhidrosis secondary to a cerebral infarct. PMID:15315923

  11. Dual release of dexamethasone and TGF-β3 from polymeric microspheres for stem cell matrix accumulation in a rat disc degeneration model.

    PubMed

    Liang, Cheng-zhen; Li, Hao; Tao, Yi-qing; Peng, Li-hua; Gao, Jian-qing; Wu, Jing-jun; Li, Fang-cai; Hua, Jian-ming; Chen, Qi-xin

    2013-12-01

    Low back pain is frequently caused by nucleus pulposus (NP) degeneration. Tissue engineering is a powerful therapeutic strategy which could restore the normal biomechanical motion of the human spine. Previously we reported that a new nanostructured three-dimensional poly(lactide-co-glycolide) (PLGA) microsphere, which is loaded with dexamethasone and growth factor embedded heparin/poly(l-lysine) nanoparticles via a layer-by-layer system, was an effective cell carrier in vitro for NP tissue engineering. This study aimed to investigate whether the implantation of adipose-derived stem cell (ADSC)-seeded PLGA microspheres into the rat intervertebral disc could regenerate the degenerated disc. Changes in disc height by plain radiograph, T2-weighted signal intensity in magnetic resonance imaging (MRI), histology, immunohistochemistry and matrix-associated gene expression were evaluated in normal controls (NCs) (without operations), a degeneration control (DC) group (with needle puncture, injected only with Dulbecco's modified Eagle's medium), a PLGA microspheres (PMs) treatment group (with needle puncture, PLGA microspheres only injection), and PLGA microspheres loaded with ADSCs treatment (PMA) group (with needle puncture, PLGA microspheres loaded with ADSC injection) for a 24-week period. The results showed that at 24 weeks post-transplantation, the PM and PMA groups regained disc height values of ∼63% and 76% and MRI signal intensities of ∼47% and 76%, respectively, compared to the NC group. Biochemistry, immunohistochemistry and gene expression analysis also indicated the restoration of proteoglycan accumulation in the discs of the PM and PMA groups. However, there was almost no restoration of proteoglycan accumulation in the discs of the DC group compared with the PM and PMA groups. Taken together, these data suggest that ADSC-seeded PLGA microspheres could partly regenerate the degenerated disc in vivo after implantation into the rat degenerative intervertebral

  12. Sympathetic regulation of cerebral blood flow during seizures in newborn lambs

    SciTech Connect

    Kurth, C.D.; Wagerle, L.C.; Delivoria-Papadopoulos, M. )

    1988-09-01

    The authors examined cerebral blood flow (CBF) regulation by the sympathetic nerves in 12 newborn lambs during seizures, a potent reflex stimulator of the sympathetic nervous system. CBF was measured with microspheres, and seizures were induced with bicuculline. In six of these lambs, one hemibrain was denervated (D) chronically by interrupting the ipsilateral cervical sympathetic trunk; the other hemibrain remained innervated (I). Before and after 10, 35, and 70 min of seizures, cerebral gray matter blood flow was measured. In the cerebral white matter, hippocampus, caudate, and thalamus blood flows to the D and I hemibrains were similar before seizures but during seizures they were 10-39% greater in the D than in the I hemibrain. Midbrain, brainstem, and cerebellum D and I blood flows were always similar. In the other six lambs, acute denervation during seizures increased ipsilateral cerebral gray and hippocampus blood flow by 10-31%, but unilateral electrical stimulation decreased ipsilateral cerebral gray, cerebral white, hippocampus, thalamus, and caudate blood flow by 17-27%. The data demonstrate that, during seizures, sympathetic nerve activity modifies regional CBF and the effect is sustained, suggesting a role for the sympathetic nervous system in newborn CBF regulation.

  13. Ultrafast microsphere near-field nanostructuring

    NASA Astrophysics Data System (ADS)

    Leitz, K.-H.; Quentin, U.; Hornung, B.; Otto, A.; Alexeev, I.; Schmidt, M.

    2011-03-01

    Due to the steadily advancing miniaturization in all fields of technology nanostructuring becomes increasingly important. Whereas the classical lithographic nanostructuring suffers from both high costs and low flexibility, for many applications in biomedicine and technology laser based nanostructuring approaches, where near-field effects allow a sub-diffraction limited laser focusing, are on the rise. In combination with ultrashort pulsed laser sources, that allow the utilization of non-linear multi-photon absorption effects, a flexible, low-cost laser based nanostructuring with sub-wavelength resolution becomes possible. Among various near-field nanostructuring approaches the microsphere based techniques, which use small microbead particles of the size of the wavelength for a sub-diffraction limited focusing of pulsed laser radiation, are the most promising. Compared to the tip or aperture based techniques this approach is very robust and can be applied both for a large-scale production of periodic arrays of nanostructures and in combination with optical trapping also for a direct-write. Size and shape of the features produced by microsphere near-field nanostructuring strongly depend on the respective processing parameters. In this contribution a basic study of the influence of processing parameters on the microsphere near-field nanostructuring with nano-, pico- and femtosecond laser pulses will be presented. The experimental and numerical results with dielectric and metal nanoparticles on semiconductor and dielectric substrates show the influence of particle size and material, substrate material, pulse duration, laser fluence, number of contributing laser pulses and polarization on the structuring process.

  14. Changes in cerebral hemodynamics during laparoscopic cholecystectomy.

    PubMed

    De Cosmo, G; Iannace, E; Primieri, P; Valente, M R; Proietti, R; Matteis, M; Silvestrini, M

    1999-10-01

    Laparoscopic surgery requires a series of procedures, including intraperitoneal CO2 insufflation, which can cause cardiovascular and hemogasanalytic modifications, potentially able to impair cerebral perfusion. The aim of this study was to evaluate changes in cerebral blood flow velocity during laparoscopic cholecystectomy. Eighteen patients undergoing laparoscopic cholecystectomy were studied. Middle cerebral artery blood flow velocity was monitored using transcranial Doppler ultrasonography. Electrical bioimpedance was employed to measure cardiac output, stroke volume and to calculate derived parameters. End-tidal CO2, mean arterial blood pressure, end expiratory anesthetic concentration and O2 saturation were monitored non-invasively. Cerebral artery blood flow velocity increased significantly after CO2 insufflation (p < 0.05) and remained stable. The highest values were reached after CO2 desufflation. A significant reduction in stroke volume and cardiac output (p < 0.05) associated with increased vascular systemic resistances (p < 0.001) was observed soon after CO2 insufflation. The decrease in cardiac output and the increase in vascular systemic resistances remained significant throughout abdominal insufflation. Heart rate and mean arterial pressure remained substantially unchanged with the exception of a significant decrease (p < 0.001) before CO2 insufflation. There was no significant change in end-tidal CO2 during abdominal insufflation. These findings suggest that the cerebrovascular system can undergo adaptive changes during all phases of laparoscopic surgery. However, the extent of cardio- and cerebrovascular variation indicates the need for careful preliminary evaluation of cerebral hemodynamics in patients with vascular disorders before laparoscopic surgery. PMID:10555187

  15. Measurements of extrinsic fluorescence in Intralipid and polystyrene microspheres

    PubMed Central

    Du Le, Vinh Nguyen; Nie, Zhaojun; Hayward, Joseph E.; Farrell, Thomas J.; Fang, Qiyin

    2014-01-01

    The fluorescence of Intralipid and polystyrene microspheres with sphere diameter of 1 µm at a representative lipid and microsphere concentration for simulation of mucosal tissue scattering has not been a subject of extensive experimental study. In order to elucidate the quantitative relationship between lipid and microsphere concentration and the respective fluorescent intensity, the extrinsic fluorescence spectra between 360 nm and 650 nm (step size of 5 nm) were measured at different lipid concentrations (from 0.25% to 5%) and different microsphere concentrations (0.00364, 0.0073, 0.0131 spheres per cubic micrometer) using laser excitation at 355 nm with pulse energy of 2.8 µJ. Current findings indicated that Intralipid has a broadband emission between 360 and 650 nm with a primary peak at 500 nm and a secondary peak at 450 nm while polystyrene microspheres have a single peak at 500 nm. In addition, for similar scattering properties the fluorescence of Intralipid solutions is approximately three-fold stronger than that of the microsphere solutions. Furthermore, Intralipid phantoms with lipid concentrations ~2% (simulating the bottom layer of mucosa) produce up to seven times stronger fluorescent emission than phantoms with lipid concentration ~0.25% (simulating the top layer of mucosa). The fluoresence decays of Intralipid and microsphere solutions were also recorded for estimation of fluorescence lifetime. PMID:25136497

  16. Measurement of thermal diffusivity of depleted uranium metal microspheres

    NASA Astrophysics Data System (ADS)

    Humrickhouse-Helmreich, Carissa J.; Corbin, Rob; McDeavitt, Sean M.

    2014-03-01

    The high void space of nuclear fuels composed of homogeneous uranium metal microspheres may allow them to achieve ultra-high burnup by accommodating fuel swelling and reducing fuel/cladding interactions; however, the relatively low thermal conductivity of microsphere nuclear fuels may limit their application. To support the development of microsphere nuclear fuels, an apparatus was designed in a glovebox and used to measure the apparent thermal diffusivity of a packed bed of depleted uranium (DU) microspheres with argon fill in the void spaces. The developed Crucible Heater Test Assembly (CHTA) recorded radial temperature changes due to an initial heat pulse from a central thin-diameter cartridge heater. Using thermocouple positions and time-temperature data, the apparent thermal diffusivity was calculated. The thermal conductivity of the DU microspheres was calculated based on the thermal diffusivity from the CHTA, known material densities and specific heat capacities, and an assumed 70% packing density based on prior measurements. Results indicate that DU metal microspheres have very low thermal conductivity, relative to solid uranium metal, and rapidly form an oxidation layer even in a low oxygen environment. At 500 °C, the thermal conductivity of the DU metal microsphere bed was 0.431 ± 0.0560 W/m-K compared to the literature value of approximately 32 W/m-K for solid uranium metal.

  17. Insulin delivery through nasal route using thiolated microspheres.

    PubMed

    Nema, Tarang; Jain, Ashish; Jain, Aviral; Shilpi, Satish; Gulbake, Arvind; Hurkat, Pooja; Jain, Sanjay K

    2013-01-01

    The aim of the present study was to investigate the potential of developed thiolated microspheres for insulin delivery through nasal route. In the present study, cysteine was immobilized on carbopol using EDAC. A total of 269.93 µmol free thiol groups per gram polymer were determined. The prepared nonthiolated and thiolated microspheres were studied for particle shape, size, drug content, swellability, mucoadhesion and in vitro insulin release. The thiolated microspheres exhibited higher mucoadhesion due to formation of covalent bonds via disulfide bridges with the mucus gel layer. Drug permeation through goat nasal mucosa of nonthiolated and thiolated microspheres were found as 52.62 ± 2.4% and 78.85 ± 3.1% in 6 h, respectively. Thiolated microspheres bearing insulin showed better reduction in blood glucose level (BGL) in comparison to nonthiolated microspheres as 31.23 ± 2.12% and 75.25 ± 0.93% blood glucose of initial BGL were observed at 6 h after nasal delivery of thiolated and nonthiolated microspheres in streptozotocin-induced diabetic rabbits.

  18. Magnetic poly(glycidyl methacrylate) microspheres for protein capture.

    PubMed

    Koubková, Jana; Müller, Petr; Hlídková, Helena; Plichta, Zdeněk; Proks, Vladimír; Vojtěšek, Bořivoj; Horák, Daniel

    2014-09-25

    The efficient isolation and concentration of protein antigens from complex biological samples is a critical step in several analytical methods, such as mass spectrometry, flow cytometry and immunochemistry. These techniques take advantage of magnetic microspheres as immunosorbents. The focus of this study was on the development of new superparamagnetic polymer microspheres for the specific isolation of the tumor suppressor protein p53. Monodisperse macroporous poly(glycidyl methacrylate) (PGMA) microspheres measuring approximately 5 μm and containing carboxyl groups were prepared by multistep swelling polymerization of glycidyl methacrylate (GMA), 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA) and ethylene dimethylacrylate (EDMA) as a crosslinker in the presence of cyclohexyl acetate as a porogen. To render the microspheres magnetic, iron oxide was precipitated within their pores; the Fe content in the particles received ∼18 wt%. Nonspecific interactions between the magnetic particles and biological media were minimized by coating the microspheres with poly(ethylene glycol) (PEG) terminated by carboxyl groups. The carboxyl groups of the magnetic PGMA microspheres were conjugated with primary amino groups of mouse monoclonal DO-1 antibody using conventional carbodiimide chemistry. The efficiency of protein p53 capture and the degree of nonspecific adsorption on neat and PEG-coated magnetic microspheres were determined by western blot analysis.

  19. Ultra-sensitive force measurement using optically levitated microspheres

    NASA Astrophysics Data System (ADS)

    Rider, Alexander; Moore, David; Gratta, Giorgio

    2015-04-01

    We have demonstrated a novel technique for measuring microscopic forces acting on optically levitated dielectric microspheres. The radiation field at the focus of a laser beam is used to levitate a microsphere in a harmonic trap where its displacement can be determined by the pattern of scattered light. Optical levitation isolates the microsphere from the surrounding environment at high vacuum, making thermal noise negligible. We have demonstrated a preliminary sensitivity of 5 ×10-17NHz - 1 / 2 for forces acting on 5 μm microspheres and expect to be able to improve this by several orders of magnitude once non-fundamental sources of noise are eliminated. The electric charge of a microsphere can be determined by applying an electric field and measuring the resulting force. We have demonstrated the ability to discharge the microspheres with single electron precision, which eliminates the most significant electrostatic backgrounds from force measurements. As a demonstration of this technique we have searched for the presence of unknown charged particles with charge > 5 ×10-5 e bound in our microspheres. Here we discuss the apparatus, the charged particle search, and outline our plans for future measurements including gravity at μm length scales.

  20. Adsorption and preconcentration of divalent metal ions in fossil fuels and biofuels: gasoline, diesel, biodiesel, diesel-like and ethanol by using chitosan microspheres and thermodynamic approach.

    PubMed

    Prado, Alexandre G S; Pescara, Igor C; Evangelista, Sheila M; Holanda, Matheus S; Andrade, Romulo D; Suarez, Paulo A Z; Zara, Luiz F

    2011-05-15

    Biodiesel and diesel-like have been obtained from soybean oil by transesterification and thermal cracking process, respectively. These biofuels were characterized as according to ANP standards by using specific ASTM methods. Ethanol, gasoline, and diesel were purchased from a gas station. Deacetylation degree of chitosan was determined by three distinct methods (conductimetry, FTIR and NMR), and the average degree was 78.95%. The chitosan microspheres were prepared from chitosan by split-coating and these spheres were crosslinked using glutaraldehyde. The surface area of microspheres was determined by BET method, and the surface area of crosslinked microspheres was 9.2m(2)g(-1). The adsorption isotherms of cooper, nickel and zinc on microspheres of chitosan were determined in petroleum derivatives (gasoline and diesel oil), as well as in biofuels (alcohol, biodiesel and diesel-like). The adsorption order in all fuels was: Cu>Ni>Zn. The elution tests presented the following preconcentration degrees: >4.5 to ethanol, >4.4 to gasoline, >4.0 to diesel, >3.8 to biodiesel and >3.6 to diesel-like. The application of chitosan microspheres in the metal ions preconcentration showed the potential of this biopolymer to enrich fuel sample in order to be analyzed by flame atomic absorption spectrometry.

  1. Adsorption and preconcentration of divalent metal ions in fossil fuels and biofuels: gasoline, diesel, biodiesel, diesel-like and ethanol by using chitosan microspheres and thermodynamic approach.

    PubMed

    Prado, Alexandre G S; Pescara, Igor C; Evangelista, Sheila M; Holanda, Matheus S; Andrade, Romulo D; Suarez, Paulo A Z; Zara, Luiz F

    2011-05-15

    Biodiesel and diesel-like have been obtained from soybean oil by transesterification and thermal cracking process, respectively. These biofuels were characterized as according to ANP standards by using specific ASTM methods. Ethanol, gasoline, and diesel were purchased from a gas station. Deacetylation degree of chitosan was determined by three distinct methods (conductimetry, FTIR and NMR), and the average degree was 78.95%. The chitosan microspheres were prepared from chitosan by split-coating and these spheres were crosslinked using glutaraldehyde. The surface area of microspheres was determined by BET method, and the surface area of crosslinked microspheres was 9.2m(2)g(-1). The adsorption isotherms of cooper, nickel and zinc on microspheres of chitosan were determined in petroleum derivatives (gasoline and diesel oil), as well as in biofuels (alcohol, biodiesel and diesel-like). The adsorption order in all fuels was: Cu>Ni>Zn. The elution tests presented the following preconcentration degrees: >4.5 to ethanol, >4.4 to gasoline, >4.0 to diesel, >3.8 to biodiesel and >3.6 to diesel-like. The application of chitosan microspheres in the metal ions preconcentration showed the potential of this biopolymer to enrich fuel sample in order to be analyzed by flame atomic absorption spectrometry. PMID:21482279

  2. Protocell-like Microspheres from Thermal Polyaspartic Acid

    NASA Astrophysics Data System (ADS)

    Bahn, Peter R.; Pappelis, Aristotel; Bozzola, John

    2006-12-01

    One of the most prominent amino acids to appear in monomer-generating origin-of-life experiments is aspartic acid. Hugo Schiff found in 1897 that aspartic acid polymerizes when heated to form polyaspartylimide which hydrolyzes in basic aqueous solution to form thermal polyaspartic acid which is a branched polypeptide. We recently reported at the ISSOL 2005 Conference that commercially made thermal polyaspartic acid forms microspheres when heated in boiling water and allowed to cool. In a new experiment we heated aspartic acid at 180°C for up to 100 h to form thermal polyaspartylimide which when heated in boiling water without addition of base hydrolyzed to form thermal polyaspartic acid which upon cooling formed microspheres. Thermal polyaspartic acid microspheres appear protocell-like in the sense of being prebiotically plausible lattices or containers that could eventually have been filled with just the right additions of primordial proteins, nucleic acids, lipids, and metabolites so as to constitute protocells capable of undergoing further chemical and biological evolution. Thermal polyaspartic acid microspheres are extremely simple models of protocells that are more amenable to precise quantitative experimental investigation than the proteinoid microspheres of Sidney W. Fox. We present here scanning electron microscope images of such thermal polyaspartic acid microspheres. Figure 1 shows thermal polyaspartic acid microspheres from l-aspartic acid heated at 180°C for 50 h, at a magnification of 3,500×. Figure 2 shows thermal polyaspartic acid microspheres from the same sample at a magnification of 7,000×. The thermal polyaspartic acid microspheres have a diameter of approximately 1 μm These images were viewed with a Hitachi S2460N scanning electron microscope at 20 kV acceleration voltage. [Figure not available: see fulltext.][Figure not available: see fulltext.

  3. The affinity of magnetic microspheres for Schistosoma eggs.

    PubMed

    Candido, Renata R F; Favero, Vivian; Duke, Mary; Karl, Stephan; Gutiérrez, Lucía; Woodward, Robert C; Graeff-Teixeira, Carlos; Jones, Malcolm K; St Pierre, Timothy G

    2015-01-01

    Schistosomiasis is a chronic parasitic disease of humans, with two species primarily causing the intestinal infection: Schistosoma mansoni and Schistosoma japonicum. Traditionally, diagnosis of schistosomiasis is achieved through direct visualisation of eggs in faeces using techniques that lack the sensitivity required to detect all infections, especially in areas of low endemicity. A recently developed method termed Helmintex™ is a very sensitive technique for detection of Schistosoma eggs and exhibits 100% sensitivity at 1.3 eggs per gram of faeces, enough to detect even low-level infections. The Helminthex™ method is based on the interaction of magnetic microspheres and schistosome eggs. Further understanding the underlying egg-microsphere interactions would enable a targeted optimisation of egg-particle binding and may thus enable a significant improvement of the Helmintex™ method and diagnostic sensitivity in areas with low infection rates. We investigated the magnetic properties of S. mansoni and S. japonicum eggs and their interactions with microspheres with different magnetic properties and surface functionalization. Eggs of both species exhibited higher binding affinity to the magnetic microspheres than the non-magnetic microspheres. Binding efficiency was further enhanced if the particles were coated with streptavidin. Schistosoma japonicum eggs bound more microspheres compared with S. mansoni. However, distinct differences within eggs of each species were also observed when the distribution of the number of microspheres bound per egg was modelled with double Poisson distributions. Using this approach, both S. japonicum and S. mansoni eggs fell into two groups, one having greater affinity for magnetic microspheres than the other, indicating that not all eggs of a species exhibit the same binding affinity. Our observations suggest that interaction between the microspheres and eggs is more likely to be related to surface charge-based electrostatic

  4. The affinity of magnetic microspheres for Schistosoma eggs.

    PubMed

    Candido, Renata R F; Favero, Vivian; Duke, Mary; Karl, Stephan; Gutiérrez, Lucía; Woodward, Robert C; Graeff-Teixeira, Carlos; Jones, Malcolm K; St Pierre, Timothy G

    2015-01-01

    Schistosomiasis is a chronic parasitic disease of humans, with two species primarily causing the intestinal infection: Schistosoma mansoni and Schistosoma japonicum. Traditionally, diagnosis of schistosomiasis is achieved through direct visualisation of eggs in faeces using techniques that lack the sensitivity required to detect all infections, especially in areas of low endemicity. A recently developed method termed Helmintex™ is a very sensitive technique for detection of Schistosoma eggs and exhibits 100% sensitivity at 1.3 eggs per gram of faeces, enough to detect even low-level infections. The Helminthex™ method is based on the interaction of magnetic microspheres and schistosome eggs. Further understanding the underlying egg-microsphere interactions would enable a targeted optimisation of egg-particle binding and may thus enable a significant improvement of the Helmintex™ method and diagnostic sensitivity in areas with low infection rates. We investigated the magnetic properties of S. mansoni and S. japonicum eggs and their interactions with microspheres with different magnetic properties and surface functionalization. Eggs of both species exhibited higher binding affinity to the magnetic microspheres than the non-magnetic microspheres. Binding efficiency was further enhanced if the particles were coated with streptavidin. Schistosoma japonicum eggs bound more microspheres compared with S. mansoni. However, distinct differences within eggs of each species were also observed when the distribution of the number of microspheres bound per egg was modelled with double Poisson distributions. Using this approach, both S. japonicum and S. mansoni eggs fell into two groups, one having greater affinity for magnetic microspheres than the other, indicating that not all eggs of a species exhibit the same binding affinity. Our observations suggest that interaction between the microspheres and eggs is more likely to be related to surface charge-based electrostatic

  5. Gelatin-methacrylamide gel loaded with microspheres to deliver GDNF in bilayer collagen conduit promoting sciatic nerve growth.

    PubMed

    Zhuang, Hai; Bu, Shoushan; Hua, Lei; Darabi, Mohammad A; Cao, Xiaojian; Xing, Malcolm

    2016-01-01

    In this study, we fabricated glial cell-line derived neurotrophic factor (GDNF)-loaded microspheres, then seeded the microspheres in gelatin-methacrylamide hydrogel, which was finally integrated with the commercial bilayer collagen membrane (Bio-Gide(®)). The novel composite of nerve conduit was employed to bridge a 10 mm long sciatic nerve defect in a rat. GDNF-loaded gelatin microspheres had a smooth surface with an average diameter of 3.9±1.8 μm. Scanning electron microscopy showed that microspheres were uniformly distributed in both the GelMA gel and the layered structure. Using enzyme-linked immunosorbent assay, in vitro release studies (pH 7.4) of GDNF from microspheres exhibited an initial burst release during the first 3 days (18.0%±1.3%), and then, a prolonged-release profile extended to 32 days. However, in an acidic condition (pH 2.5), the initial release percentage of GDNF was up to 91.2%±0.9% within 4 hours and the cumulative release percentage of GDNF was 99.2%±0.2% at 48 hours. Then the composite conduct was implanted in a 10 mm critical defect gap of sciatic nerve in a rat. We found that the nerve was regenerated in both conduit and autograft (AG) groups. A combination of electrophysiological assessment and histomorphometry analysis of regenerated nerves showed that axonal regeneration and functional recovery in collagen tube filled with GDNF-loaded microspheres (GM + CT) group were similar to AG group (P>0.05). Most myelinated nerves were matured and arranged densely with a uniform structure of myelin in a neat pattern along the long axis in the AG and GM + CT groups, however, regenerated nerve was absent in the BLANK group, left the 10 mm gap empty after resection, and the nerve fiber exhibited a disordered arrangement in the collagen tube group. These results indicated that the hybrid system of bilayer collagen conduit and GDNF-loaded gelatin microspheres combined with gelatin-methacrylamide hydrogels could serve as a new biodegradable

  6. Gelatin-methacrylamide gel loaded with microspheres to deliver GDNF in bilayer collagen conduit promoting sciatic nerve growth

    PubMed Central

    Zhuang, Hai; Bu, Shoushan; Hua, Lei; Darabi, Mohammad A; Cao, Xiaojian; Xing, Malcolm

    2016-01-01

    In this study, we fabricated glial cell-line derived neurotrophic factor (GDNF)-loaded microspheres, then seeded the microspheres in gelatin-methacrylamide hydrogel, which was finally integrated with the commercial bilayer collagen membrane (Bio-Gide®). The novel composite of nerve conduit was employed to bridge a 10 mm long sciatic nerve defect in a rat. GDNF-loaded gelatin microspheres had a smooth surface with an average diameter of 3.9±1.8 μm. Scanning electron microscopy showed that microspheres were uniformly distributed in both the GelMA gel and the layered structure. Using enzyme-linked immunosorbent assay, in vitro release studies (pH 7.4) of GDNF from microspheres exhibited an initial burst release during the first 3 days (18.0%±1.3%), and then, a prolonged-release profile extended to 32 days. However, in an acidic condition (pH 2.5), the initial release percentage of GDNF was up to 91.2%±0.9% within 4 hours and the cumulative release percentage of GDNF was 99.2%±0.2% at 48 hours. Then the composite conduct was implanted in a 10 mm critical defect gap of sciatic nerve in a rat. We found that the nerve was regenerated in both conduit and autograft (AG) groups. A combination of electrophysiological assessment and histomorphometry analysis of regenerated nerves showed that axonal regeneration and functional recovery in collagen tube filled with GDNF-loaded microspheres (GM + CT) group were similar to AG group (P>0.05). Most myelinated nerves were matured and arranged densely with a uniform structure of myelin in a neat pattern along the long axis in the AG and GM + CT groups, however, regenerated nerve was absent in the BLANK group, left the 10 mm gap empty after resection, and the nerve fiber exhibited a disordered arrangement in the collagen tube group. These results indicated that the hybrid system of bilayer collagen conduit and GDNF-loaded gelatin microspheres combined with gelatin-methacrylamide hydrogels could serve as a new biodegradable

  7. Development of packaged silica microspheres coupled with tapered optical microfibres

    NASA Astrophysics Data System (ADS)

    Wang, Pengfei; Madugani, Ramgopal; Zhao, Haoyu; Ward, Jonathan; Yang, Yong; Farrell, Gerald; Brambilla, Gilberto; Nic Chormaic, Síle

    2016-03-01

    In this research, we present a packaged add-drop filter composed of a silica microsphere resonator and a strongly coupled optical microfiber coupler. A one-step fabrication process using UV curable epoxy is shown to stabilize the microsphere resonator coupled to the microfiber coupler, which is used as add and drop ports. A high Q-factor of 3×107 is obtained at around 780 nm from the packaged microspheres coupled with the microfiber coupler in the add-drop configuration.

  8. Observation of whispering gallery modes in microtube-microspheres system

    NASA Astrophysics Data System (ADS)

    Li, Hanyang; Hao, Sue; Qiang, Liangsheng; Li, Jin; Zhang, Yundong

    2013-06-01

    We proposed that a fluorescent microsphere with diameter of 6 μm was manipulated into a microtube with inner diameter of 6.2 μm. The whispering gallery modes (WGMs) of fluorescence resonance were observed by 532 nm laser pumping the microspheres-mircotube system. Another microsphere with the same diameter was manipulated into the microtube and mode splitting in the system of two spheres in contact in the mircotube was demonstrated. We also discussed relationship between WGMs peak intensity and the excitation power. The scheme will bring more insight into the applications of WGMs for biomedical diagnostics and microfluidics.

  9. Development of prilling process for biodegradable microspheres through experimental designs.

    PubMed

    Fabien, Violet; Minh-Quan, Le; Michelle, Sergent; Guillaume, Bastiat; Van-Thanh, Tran; Marie-Claire, Venier-Julienne

    2016-02-10

    The prilling process proposes a microparticle formulation easily transferable to the pharmaceutical production, leading to monodispersed and highly controllable microspheres. PLGA microspheres were used for carrying an encapsulated protein and adhered stem cells on its surface, proposing a tool for regeneration therapy against injured tissue. This work focused on the development of the production of PLGA microspheres by the prilling process without toxic solvent. The required production quality needed a complete optimization of the process. Seventeen parameters were studied through experimental designs and led to an acceptable production. The key parameters and mechanisms of formation were highlighted. PMID:26656302

  10. Packaged chalcogenide microsphere resonator with high Q-factor

    NASA Astrophysics Data System (ADS)

    Wang, Pengfei; Ding, Ming; Lee, Timothy; Senthil Murugan, Ganapathy; Bo, Lin; Semenova, Yuliya; Wu, Qiang; Hewak, Dan; Brambilla, Gilberto; Farrell, Gerald

    2013-04-01

    The fabrication and characterization of a packaged As2S3 microsphere resonator coupled to a tapered fiber using a low refractive index UV-curable polymer are reported. Embedding provides an efficient means to remove the highest order whispering gallery modes in the microsphere resonator, thus cleaning the resonator spectrum. At wavelengths near 1549.5 nm, high-Q modes up to 1.8 × 105 can be efficiently excited in a 110 μm diameter chalcogenide microsphere via evanescent coupling from a 2 μm diameter tapered silica fiber. The device photosensitivity, useful for tuning, is still present and useable after the packaging process.

  11. Effect of size of silica microspheres on photonic band gap

    SciTech Connect

    Dhiman, N. Sharma, A. Gathania, A. K.; Singh, B. P.

    2014-04-24

    In present work photonic crystals of different size of silica microspheres have been fabricated. The optical properties of these developed photonic crystals have been studied using UV-visible spectroscopy. UV-visible spectroscopy shows that they have photonic band gap that can be tuned in visible and infrared regime by changing the size of silica microspheres. The photonic band gap structures of these photonic crystals have been calculated using MIT photonic band gap package. It also reveals that with the increase in size of silica microspheres the photonic band gap shifts to lower energy region.

  12. Protein specific fluorescent microspheres for labelling a protein

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor)

    1982-01-01

    Highly fluorescent, stable and biocompatible microspheres are obtained by copolymerizing an acrylic monomer containing a covalent bonding group such as hydroxyl, amine or carboxyl, for example, hydroxyethylmethacrylate, with an addition polymerizable fluorescent comonomer such as dansyl allyl amine. A lectin or antibody is bound to the covalent site to provide cell specificity. When the microspheres are added to a cell suspension the marked microspheres will specifically label a cell membrane by binding to a specific receptor site thereon. The labeled membrane can then be detected by fluorescence of the fluorescent monomer.

  13. Preparation and properties of polyvinyl alcohol microspheres

    SciTech Connect

    Campbell, J.H.; Grens, J.Z.; Poco, J.F.; Ives, B.H.

    1986-06-01

    Polyvinyl alcohol (PVA) microspheres, having a size range of approx.150- to 250-..mu..m diameter with 1- to 5-..mu..m wall thickness, have been fabricated using a solution droplet technique. The spheres were developed for possible use on the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program. PVA, a polymer chosen based on earlier survey work carried out at KMS Fusion, Inc., has good strength, low hydrogen permeability, is optically transparent, and water soluble. The latter property makes it safe and easy to use in our droplet generator system. A unique dual-orifice droplet generator was used to prepare the spheres. The droplet generator operating conditions and the column processing parameters were chosen using results from our 1-D model calculations as a guide. The polymer microsphere model is an extension of the model we developed to support the glass sphere production. After preparation, the spheres were physically characterized for surface quality, sphericity, wall thickness (and uniformity), and size. We also determined the buckling pressure for both uncoated and CH-coated spheres. Radiation stability to beta decay (from tritium) was evaluated by exposing the spheres to a 7-keV electron beam. The results from these and other physical property measurements are presented in this report.

  14. Ontogeny of cerebral oxidative metabolism in the chick embryo.

    PubMed

    Gonya-Magee, T; Vannucci, R C

    1982-05-01

    The low cerebral energy requirements of most mammals at birth reflect an immaturity of the central nervous system, and it has been suggested that energy demands in fetuses are even less well developed than in newborns. Furthermore, fetal cerebral energy requirements are presumed to be met predominantly or exclusively by anaerobic glycolysis. To clarify these issues, we investigated cerebral oxidative metabolism in 9-, 14-, 16-, and 19-day-old chick embryos and in newly hatched peeps. Animals were decapitated and quick-frozen in liquid Freon 0--5 min post-mortem. Forebrain extracts were prepared and assayed for ATP, phosphocreatine, glucose, and lactate. Alterations in these metabolites post-decapitation were used to calculate cerebral metabolic rates (delta similar to P) and rates of maximal anaerobic glycolysis (delta lactate). Rates of lactate accumulation during cerebral ischemia increased progressively from embryonic day 9 through hatching. Cerebral metabolic rates were not different in 9-, 14-, and 15-day-old embryos, but increased steadily thereafter. The extent to which total cerebral energy utilization could be derived from anaerobic glycolysis (delta lactate/delta similar to P) increased from a low at day 9 (0.29) to a maximum at day 16 (0.78). The data suggest that, despite the low cerebral metabolic activity of the chick embryo, at no time during development is anaerobic glycolysis capable of entirely supporting the energy needs of the developing brain.

  15. Acquired Cerebral Trauma: Epilogue.

    ERIC Educational Resources Information Center

    Bigler, Erin D., Ed.

    1988-01-01

    The article summarizes a series of articles concerning acquired cerebral trauma. Reviewed are technological advances, treatment, assessment, potential innovative therapies, long-term outcome, family impact of chronic brain injury, and prevention. (DB)

  16. Synthesis and spectral characterization of Zn(II) microsphere series for antimicrobial application

    NASA Astrophysics Data System (ADS)

    Singh, Ajay K.; Pandey, Sarvesh K.; Pandey, O. P.; Sengupta, S. K.

    2014-09-01

    Microsphere series have been synthesized by reacting zinc(II) acetate dihydrate with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole/oxadiazole/triazole with salicylaldehyde. Elemental analysis suggests that the complexes have 1:2 and 1:1 stoichiometry of the type [Zn(L)2(H2O)2] and [Zn(L‧)(H2O)2]; LH = Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thia/oxadiazole with salicylaldehyde; L‧H2 = Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1,2,4-triazole and salicylaldehyde and were characterized by elemental analyses, IR, 1H NMR and 13C NMR spectral data. Scanning electron microscopy (SEM) showed that synthesized materials have microsphere like structure and there EDX analysis comparably matches with elemental analysis. For the antimicrobial application Schiff bases and their zinc(II) complexes were screened for four bacteria e.g. Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Streptococcus pyogenes and four fungi e.g. Cyrtomium falcatum, Aspergillus niger, Fusarium oxysporium and Curvularia pallescence by the reported method. Schiff base and Zn(II) compounds showed significant antimicrobial activities. However, activities increase upon chelation. Thermal analysis (TGA) data of compound (10) showed its stability up to 300 °C.

  17. Regional brain blood flow and cerebral hemispheric oxygen consumption during acute hypoxaemia in the llama fetus

    PubMed Central

    Llanos, Aníbal J; Riquelme, Raquel A; Sanhueza, Emilia M; Herrera, Emilio; Cabello, Gertrudis; Giussani, Dino A; Parer, Julian T

    2002-01-01

    Unlike fetal animals of lowland species, the llama fetus does not increase its cerebral blood flow during an episode of acute hypoxaemia. This study tested the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral O2 extraction rather than decreasing cerebral oxygen utilisation during acute hypoxaemia. Six llama fetuses were surgically instrumented under general anaesthesia at 217 days of gestation (term ca 350 days) with vascular and amniotic catheters in order to carry out cardiorespiratory studies. Following a control period of 1 h, the llama fetuses underwent 3 × 20 min episodes of progressive hypoxaemia, induced by maternal inhalational hypoxia. During basal conditions and during each of the 20 min of hypoxaemia, fetal cerebral blood flow was measured with radioactive microspheres, cerebral oxygen extraction was calculated, and fetal cerebral hemispheric O2 consumption was determined by the modified Fick principle. During hypoxaemia, fetal arterial O2 tension and fetal pH decreased progressively from 24 ± 1 to 20 ± 1 Torr and from 7.36 ± 0.01 to 7.33 ± 0.01, respectively, during the first 20 min episode, to 16 ± 1 Torr and 7.25 ± 0.05 during the second 20 min episode and to 14 ± 1 Torr and 7.21 ± 0.04 during the final 20 min episode. Fetal arterial partial pressure of CO2 (Pa,CO2, 42 ± 2 Torr) remained unaltered from baseline throughout the experiment. Fetal cerebral hemispheric blood flow and cerebral hemispheric oxygen extraction were unaltered from baseline during progressive hypoxaemia. In contrast, a progressive fall in fetal cerebral hemispheric oxygen consumption occurred during the hypoxaemic challenge. In conclusion, these data do not support the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral hemispheric O2 extraction. Rather, the data show that in the llama fetus, a reduction in cerebral hemispheric metabolism occurs during acute

  18. Nanomedicine in cerebral palsy.

    PubMed

    Balakrishnan, Bindu; Nance, Elizabeth; Johnston, Michael V; Kannan, Rangaramanujam; Kannan, Sujatha

    2013-01-01

    Cerebral palsy is a chronic childhood disorder that can have diverse etiologies. Injury to the developing brain that occurs either in utero or soon after birth can result in the motor, sensory, and cognitive deficits seen in cerebral palsy. Although the etiologies for cerebral palsy are variable, neuroinflammation plays a key role in the pathophysiology of the brain injury irrespective of the etiology. Currently, there is no effective cure for cerebral palsy. Nanomedicine offers a new frontier in the development of therapies for prevention and treatment of brain injury resulting in cerebral palsy. Nanomaterials such as dendrimers provide opportunities for the targeted delivery of multiple drugs that can mitigate several pathways involved in injury and can be delivered specifically to the cells that are responsible for neuroinflammation and injury. These materials also offer the opportunity to deliver agents that would promote repair and regeneration in the brain, resulting not only in attenuation of injury, but also enabling normal growth. In this review, the current advances in nanotechnology for treatment of brain injury are discussed with specific relevance to cerebral palsy. Future directions that would facilitate clinical translation in neonates and children are also addressed.

  19. Polycrystalline metasurface perfect absorbers fabricated using microsphere photolithography.

    PubMed

    Qu, Chuang; Kinzel, Edward C

    2016-08-01

    Microsphere photolithography (MPL) is a practical, cost-effective nanofabrication technique. It uses self-assembled microspheres in contact with the photoresist as microlenses. The microspheres focus incident light to a sub-diffraction limited array of photonic jets in the photoresist. This Letter explores the MPL technique to pattern metal-insulator-metal metasurfaces with near-perfect absorption at mid-wave infrared (MWIR) frequencies. Experimental results are compared to electromagnetic simulations of both the exposure process and the metasurface response. The microsphere self-assembly technique results in a polycrystalline metasurface; however, the metal-insulator-metal structure is shown to be defect tolerant. While the MPL approach imposes geometric constraints on the metasurface design, once understood, the technique can be used to create functional devices. In particular, the ability to tune the resonant wavelength with the exposure dose raises the potential of hierarchical structures.

  20. Super-focusing of center-covered engineered microsphere.

    PubMed

    Wu, Mengxue; Chen, Rui; Soh, Jiahao; Shen, Yue; Jiao, Lishi; Wu, Jianfeng; Chen, Xudong; Ji, Rong; Hong, Minghui

    2016-01-01

    Engineered microsphere possesses the advantage of strong light manipulation at sub-wavelength scale and emerges as a promising candidate to shrink the focal spot size. Here we demonstrated a center-covered engineered microsphere which can adjust the transverse component of the incident beam and achieve a sharp photonic nanojet. Modification of the beam width and working distance of the photonic nanojet were achieved by tuning the cover ratio of the engineered microsphere, leading to a sharp spot size which exceeded the optical diffraction limit. At a wavelength of 633 nm, a focal spot of 245 nm (0.387 λ) was achieved experimentally under plane wave illumination. Strong localized field with Bessel-like distribution was demonstrated by employing the linearly polarized beam and a center-covered mask being engineered on the microsphere. PMID:27528093

  1. Super-focusing of center-covered engineered microsphere.

    PubMed

    Wu, Mengxue; Chen, Rui; Soh, Jiahao; Shen, Yue; Jiao, Lishi; Wu, Jianfeng; Chen, Xudong; Ji, Rong; Hong, Minghui

    2016-01-01

    Engineered microsphere possesses the advantage of strong light manipulation at sub-wavelength scale and emerges as a promising candidate to shrink the focal spot size. Here we demonstrated a center-covered engineered microsphere which can adjust the transverse component of the incident beam and achieve a sharp photonic nanojet. Modification of the beam width and working distance of the photonic nanojet were achieved by tuning the cover ratio of the engineered microsphere, leading to a sharp spot size which exceeded the optical diffraction limit. At a wavelength of 633 nm, a focal spot of 245 nm (0.387 λ) was achieved experimentally under plane wave illumination. Strong localized field with Bessel-like distribution was demonstrated by employing the linearly polarized beam and a center-covered mask being engineered on the microsphere.

  2. Super-focusing of center-covered engineered microsphere

    NASA Astrophysics Data System (ADS)

    Wu, Mengxue; Chen, Rui; Soh, Jiahao; Shen, Yue; Jiao, Lishi; Wu, Jianfeng; Chen, Xudong; Ji, Rong; Hong, Minghui

    2016-08-01

    Engineered microsphere possesses the advantage of strong light manipulation at sub-wavelength scale and emerges as a promising candidate to shrink the focal spot size. Here we demonstrated a center-covered engineered microsphere which can adjust the transverse component of the incident beam and achieve a sharp photonic nanojet. Modification of the beam width and working distance of the photonic nanojet were achieved by tuning the cover ratio of the engineered microsphere, leading to a sharp spot size which exceeded the optical diffraction limit. At a wavelength of 633 nm, a focal spot of 245 nm (0.387 λ) was achieved experimentally under plane wave illumination. Strong localized field with Bessel-like distribution was demonstrated by employing the linearly polarized beam and a center-covered mask being engineered on the microsphere.

  3. Super-focusing of center-covered engineered microsphere

    PubMed Central

    Wu, Mengxue; Chen, Rui; Soh, Jiahao; Shen, Yue; Jiao, Lishi; Wu, Jianfeng; Chen, Xudong; Ji, Rong; Hong, Minghui

    2016-01-01

    Engineered microsphere possesses the advantage of strong light manipulation at sub-wavelength scale and emerges as a promising candidate to shrink the focal spot size. Here we demonstrated a center-covered engineered microsphere which can adjust the transverse component of the incident beam and achieve a sharp photonic nanojet. Modification of the beam width and working distance of the photonic nanojet were achieved by tuning the cover ratio of the engineered microsphere, leading to a sharp spot size which exceeded the optical diffraction limit. At a wavelength of 633 nm, a focal spot of 245 nm (0.387 λ) was achieved experimentally under plane wave illumination. Strong localized field with Bessel-like distribution was demonstrated by employing the linearly polarized beam and a center-covered mask being engineered on the microsphere. PMID:27528093

  4. Polycrystalline metasurface perfect absorbers fabricated using microsphere photolithography.

    PubMed

    Qu, Chuang; Kinzel, Edward C

    2016-08-01

    Microsphere photolithography (MPL) is a practical, cost-effective nanofabrication technique. It uses self-assembled microspheres in contact with the photoresist as microlenses. The microspheres focus incident light to a sub-diffraction limited array of photonic jets in the photoresist. This Letter explores the MPL technique to pattern metal-insulator-metal metasurfaces with near-perfect absorption at mid-wave infrared (MWIR) frequencies. Experimental results are compared to electromagnetic simulations of both the exposure process and the metasurface response. The microsphere self-assembly technique results in a polycrystalline metasurface; however, the metal-insulator-metal structure is shown to be defect tolerant. While the MPL approach imposes geometric constraints on the metasurface design, once understood, the technique can be used to create functional devices. In particular, the ability to tune the resonant wavelength with the exposure dose raises the potential of hierarchical structures. PMID:27472578

  5. Preparation of microspheres by an emulsification-complexation method.

    PubMed

    Kim, Jin-Chul; Song, Myeong-Eun; Lee, Eun-Joo; Park, Seung-Kyu; Rang, Moon-Jeong; Ahn, Ho-Jeong

    2002-04-01

    Microspheres were prepared by complexation of a cationic polymer, polyquaternium-24, and an anionic surfactant, sodium lauryl sulfate (SLS). The cationic polymer solution was emulsified in dimethylsiloxane to give water in silicone emulsion (W/Si), and it was used as a template for the formation of microspheres. The emulsion was dispersed into the SLS solution. In this process, two kinds of droplets, silicone dropletes and microspheres composed of the cationic polymer and SLS, were formed, evidenced by X-ray energy dispersive spectra. The mean diameter of the microspheres was reduced from 105.7 to 64.8 mum as the stirring rate for W/Si preparation increased from 300 to 1000 rpm. It is believed that water droplets in W/Si emulsion, when exposed to SLS solution, could be solidified by the complexation of the cationic polymer and the anionic surfactant.

  6. Super-Resolution Real Imaging in Microsphere-Assisted Microscopy

    PubMed Central

    Wang, Feifei; Li, Yi; Jia, Boliang; Liu, Lianqing; Li, Wen Jung

    2016-01-01

    Microsphere-assisted microscopy has received a lot of attention recently due to its simplicity and its capability to surpass the diffraction limit. However, to date, sub-diffraction-limit features have only been observed in virtual images formed through the microspheres. We show that it is possible to form real, super-resolution images using high-refractive index microspheres. Also, we report on how changes to a microsphere’s refractive index and size affect image formation and planes. The relationship between the focus position and the additional magnification factor is also investigated using experimental and theoretical methods. We demonstrate that such a real imaging mode, combined with the use of larger microspheres, can enlarge sub-diffraction-limit features up to 10 times that of wide-field microscopy’s magnification with a field-of-view diameter of up to 9 μm. PMID:27768774

  7. Preparation of microspheres by an emulsification-complexation method.

    PubMed

    Kim, Jin-Chul; Song, Myeong-Eun; Lee, Eun-Joo; Park, Seung-Kyu; Rang, Moon-Jeong; Ahn, Ho-Jeong

    2002-04-01

    Microspheres were prepared by complexation of a cationic polymer, polyquaternium-24, and an anionic surfactant, sodium lauryl sulfate (SLS). The cationic polymer solution was emulsified in dimethylsiloxane to give water in silicone emulsion (W/Si), and it was used as a template for the formation of microspheres. The emulsion was dispersed into the SLS solution. In this process, two kinds of droplets, silicone dropletes and microspheres composed of the cationic polymer and SLS, were formed, evidenced by X-ray energy dispersive spectra. The mean diameter of the microspheres was reduced from 105.7 to 64.8 mum as the stirring rate for W/Si preparation increased from 300 to 1000 rpm. It is believed that water droplets in W/Si emulsion, when exposed to SLS solution, could be solidified by the complexation of the cationic polymer and the anionic surfactant. PMID:16290495

  8. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    Farquar, G; Leif, R

    2009-07-15

    Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  9. Effects of naftidrofuryl on cerebral hemodynamics, metabolism and function after a retracted ischaemia.

    PubMed

    Le Poncin-Lafitte, M; Grosdemouge, C; Roy-Billon, C; Duterte, D; Rapin, J R

    1982-12-01

    Unilateral microemboli were formed in the brains of Long Evans rats by means of an intracarotid injection of microspheres (50 mu). This embolization resulted in a decrease in blood flow, severe cerebral oedema and a modification of glucose uptake. Furthermore, these microemboli affected a conditioned avoidance response. Naftidrofuryl enabled a better recovery of the processes involved in the expression of acquisition. This has been related to a decrease in the development of oedema on one side and to a better glucose uptake on the other. These data demonstrated that naftidrofuryl influences the sequelae of rapidly regressive ischaemia. PMID:7165427

  10. X- And y-axis driver for rotating microspheres

    DOEpatents

    Weinstein, Berthold W.

    1979-01-01

    Apparatus for precise control of the motion and position of microspheres for examination of their interior and/or exterior. The apparatus includes an x- and y-axis driver mechanism controlled, for example, by a minicomputer for selectively rotating microspheres retained between a pair of manipulator arms having flat, smooth end surfaces. The driver mechanism includes an apertured plate and ball arrangement which provided for coupled equal and opposite movement of the manipulator arms in two perpendicular directions.

  11. ENCAPSULATION OF PALLADIUM IN POROUS WALL HOLLOW GLASS MICROSPHERES

    SciTech Connect

    Heung, L; George Wicks, G; Ray Schumacher, R

    2008-04-09

    A new encapsulation method was investigated in an attempt to develop an improved palladium packing material for hydrogen isotope separation. Porous wall hollow glass microspheres (PWHGMs) were produced by using a flame former, heat treating and acid leaching. The PWHGMs were then filled with palladium salt using a soak-and-dry process. The palladium salt was reduced at high temperature to leave palladium inside the microspheres.

  12. Hierarchical {001}-faceted BiOBr microspheres as a novel biomimetic catalyst: dark catalysis towards colorimetric biosensing and pollutant degradation

    NASA Astrophysics Data System (ADS)

    Li, Lili; Ai, Lunhong; Zhang, Caihong; Jiang, Jing

    2014-04-01

    In recent years, considerable effort has been devoted to finding novel enzyme mimetics with improved catalytic activities. However, the insightful understanding of such catalytic process is still elusive. In this paper, we report for the first time a typical photoactive layer-structured BiOBr as a novel biomimetic catalyst possessing highly efficient intrinsic peroxidase-like activity. Moreover, we have experimentally achieved high dark peroxidase-like catalytic activity in BiOBr microspheres and provided some new insights into the light-enhanced peroxidase-like catalytic property. On the basis of a typical color reaction derived from catalytic oxidation of peroxidase substrates over BiOBr microspheres with H2O2, the simple and sensitive colorimetric assays for detection of H2O2, glucose and ascorbic acid were successfully established. More interestingly, the BiOBr microspheres showed strong ability towards activation of H2O2, displaying excellent dark catalytic activity for the degradation of organic dye. It is therefore believed that our findings in this study could open up the possibility of utilizing BiOBr as enzymatic mimics in biotechnology and environmental remediation.In recent years, considerable effort has been devoted to finding novel enzyme mimetics with improved catalytic activities. However, the insightful understanding of such catalytic process is still elusive. In this paper, we report for the first time a typical photoactive layer-structured BiOBr as a novel biomimetic catalyst possessing highly efficient intrinsic peroxidase-like activity. Moreover, we have experimentally achieved high dark peroxidase-like catalytic activity in BiOBr microspheres and provided some new insights into the light-enhanced peroxidase-like catalytic property. On the basis of a typical color reaction derived from catalytic oxidation of peroxidase substrates over BiOBr microspheres with H2O2, the simple and sensitive colorimetric assays for detection of H2O2, glucose and

  13. Development and characterization of fast responding pressure sensitive microspheres.

    PubMed

    Kimura, Fletcher; Rodriguez, Miguel; McCann, Jesse; Carlson, Brenden; Dabiri, Dana; Khalil, Gamal E; Callis, James B; Xia, Younan; Gouterman, Martin

    2008-07-01

    The response times of pressure sensitive paint (PSP) and pressure sensitive microspheres to passing shockwaves were measured to investigate their ability to accurately determine pressure changes in unsteady flows. The PSPs tested used platinum tetra(pentafluorophenyl)porphine (PtTFPP), platinum octaethylporphine (PtOEP), and a novel set of osmium-based organometallic complexes as pressure sensitive luminophors incorporated into polymer matrices of dimethylsiloxane bisphenol A-polycarbonate block copolymer or polystyrene. Two types of pressure sensitive microspheres were used, the first being PtOEP-doped polystyrene microspheres (PSBeads) and the second being porous silicon dioxide microspheres containing the novel, pressure sensitive osmium complexes. Response times for the platinum-based PSPs ranged from 47.2 to 53.0 micros, while the osmium-based PSPs ranged between 37.6 and 58.9 micros. For the microspheres, 2.5 microm diameter PSBeads showed a response time of 3.15 ms, while the osmium-based silicon dioxide microspheres showed a response time ranging between 13.6 and 18.9 micros.

  14. Drug encapsulated aerosolized microspheres as a biodegradable, intelligent glioma therapy.

    PubMed

    Floyd, J Alaina; Galperin, Anna; Ratner, Buddy D

    2016-02-01

    The grim prognosis for patients diagnosed with malignant gliomas necessitates the development of new therapeutic strategies for localized and sustained drug delivery to combat tumor drug resistance and regrowth. Here we introduce drug encapsulated aerosolized microspheres as a biodegradable, intelligent glioma therapy (DREAM BIG therapy). DREAM BIG therapy is envisioned to deliver three chemotherapeutics, temporally staged over one year, via a bioadhesive, biodegradable spray directly to the brain surgical site after tumor excision. In this proof-of-principle article exploring key components of the DREAM BIG therapy prototype, rhodamine B (RB) encapsulated poly(lactic-co-glycolic acid) and immunoglobulin G (IgG) encapsulated poly(lactic acid) microspheres were formulated and characterized. The encapsulation efficiency of RB and IgG and the release kinetics of the model drugs from the microspheres were elucidated in addition to the release kinetics of RB from poly(lactic-co-glycolic acid) microspheres formulated in a degradable poly(N-isopropylacrylamide) solution. The successful aerosolized application onto brain tissue ex-vivo demonstrated the conformal adhesion of the RB encapsulated poly(lactic-co-glycolic acid) microspheres to the convoluted brain surface mediated by the thermoresponsive carrier, poly(N-isopropylacrylamide). These preliminary results suggest the potential of the DREAM BIG therapy for future use with multiple chemotherapeutics and microsphere types to combat gliomas at a localized site. PMID:26238392

  15. Fractionating Polymer Microspheres as Highly Accurate Density Standards.

    PubMed

    Bloxham, William H; Hennek, Jonathan W; Kumar, Ashok A; Whitesides, George M

    2015-07-21

    This paper describes a method of isolating small, highly accurate density-standard beads and characterizing their densities using accurate and experimentally traceable techniques. Density standards have a variety of applications, including the characterization of density gradients, which are used to separate objects in a variety of fields. Glass density-standard beads can be very accurate (±0.0001 g cm(-3)) but are too large (3-7 mm in diameter) for many applications. When smaller density standards are needed, commercial polymer microspheres are often used. These microspheres have standard deviations in density ranging from 0.006 to 0.021 g cm(-3); these distributions in density make these microspheres impractical for applications demanding small steps in density. In this paper, commercial microspheres are fractionated using aqueous multiphase systems (AMPS), aqueous mixture of polymers and salts that spontaneously separate into phases having molecularly sharp steps in density, to isolate microspheres having much narrower distributions in density (standard deviations from 0.0003 to 0.0008 g cm(-3)) than the original microspheres. By reducing the heterogeneity in densities, this method reduces the uncertainty in the density of any specific bead and, therefore, improves the accuracy within the limits of the calibration standards used to characterize the distributions in density.

  16. In vitro and in vivo characterization of biodegradable enoxacin microspheres.

    PubMed

    Abazinge, M; Jackson, T; Yang, Q; Owusu-Ababio, G

    2000-03-01

    The in vitro release and plasma concentration profiles of sustained release enoxacin microspheres intended for the treatment of bone and systemic infections due to sensitive strains of bacteria were investigated. Microspheres of enoxacin were prepared by using poly(glycolic acid-co-DL-lactic acid) (PLGA) by the emulsion solvent evaporation technique and characterized by in vitro release in an incubator, and in vivo release in the rat subcutaneous model. The microspheres were spherical in nature, and particle size range had a significant influence on the in vitro release. The enoxacin plasma concentration 2 h after the administration of treatments was two-fold higher in animals who received the free drug compared with those who received microspheres of size range 125-250 microm. The plasma of animals who received the free drug was depleted of enoxacin by the end of the first day. However, the plasma concentration of enoxacin in the animals who received microspheres was sustained above 0.5 microg/ml for about 8 days. The results show that biodegradable microspheres of enoxacin can be prepared which release the antibiotic in vivo for days following a subcutaneous administration. This should provide a means for the sustained treatment of infections due to sensitive strains of bacteria.

  17. Abiogenic Photophosphorylation of ADP to ATP Sensitized by Flavoproteinoid Microspheres

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Michael P.; Telegina, Taisiya A.; Lyudnikova, Tamara A.; Kritsky, Mikhail S.

    2008-06-01

    A model for abiogenic photophosphorylation of ADP by orthophosphate to yield ATP was studied. The model is based on the photochemical activity of flavoproteinoid microspheres that are formed by aggregation in an aqueous medium of products of thermal condensation of a glutamic acid, glycine and lysine mixture (8:3:1) and contain, along with amino acid polymers (proteinoids), abiogenic isoalloxazine (flavin) pigments. Irradiation of aqueous suspensions of microspheres with blue visible light or ultraviolet in the presence of ADP and orthophosphate resulted in ATP formation. The yield of ATP in aerated suspensions was 10 20% per one mol of starting ADP. Deaeration reduced the photophosphorylating activity of microspheres five to 10 times. Treatment of aerated microsphere suspensions with superoxide dismutase during irradiation partially suppressed ATP formation. Deaerated microspheres restored completely their photophosphorylating activity after addition of hydrogen peroxide to the suspension. The photophosphorylating activity of deaerated suspensions of flavoproteinoid microspheres was also recovered by introduction of Fe3+-cytochrome c, an electron acceptor alternative to oxygen. On the basis of the results obtained, a chemical mechanism of phosphorylation is proposed in which the free radical form of reduced flavin sensitizer left( {{text{FlH}}^ bullet } right) and ADP are involved.

  18. Con-A conjugated mucoadhesive microspheres for the colonic delivery of diloxanide furoate.

    PubMed

    Anande, Nalini M; Jain, Sunil K; Jain, Narendra K

    2008-07-01

    The aim of the research work was to develop cyst-targeted novel concanavalin-A (Con-A) conjugated mucoadhesive microspheres of diloxanide furoate (DF) for the effective treatment of amoebiasis. Eudragit microspheres of DF were prepared using emulsification-solvent evaporation method. Formulations were characterized for particle size and size distribution, % drug entrapment, surface morphology and in vitro drug release in simulated gastrointestinal (GI) fluids. Eudragit microspheres of DF were conjugated with Con-A. IR spectroscopy and DSC were used to confirm successful conjugation of Con-A to Eudragit microspheres while Con-A conjugated microspheres were further characterized using the parameters of zeta potential, mucoadhesiveness to colonic mucosa and Con-A conjugation efficiency with microspheres. IR studies confirmed the attachment of Con-A with Eudragit microspheres. All the microsphere formulations showed good % drug entrapment (78+/-5%). Zeta potential of Eudragit microspheres and Con-A conjugated Eudragit microspheres were found to be 3.12+/-0.7mV and 16.12+/-0.5mV, respectively. Attachment of lectin to the Eudragit microspheres significantly increases the mucoadhesiveness and also controls the release of DF in simulated GI fluids. Gamma scintigraphy study suggested that Eudragit S100 coated gelatin capsule retarded the release of Con-A conjugated microspheres at low pH and released microspheres slowly at pH 7.4 in the colon.

  19. Cerebral Vascular Control and Metabolism in Heat Stress.

    PubMed

    Bain, Anthony R; Nybo, Lars; Ainslie, Philip N

    2015-07-01

    This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0 °C core temperature), the associated reduction in CBF (∼ 30%) and increase in cerebral metabolic demand (∼ 10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control--for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases. PMID:26140721

  20. Microspheres and Nanotechnology for Drug Delivery.

    PubMed

    Jóhannesson, Gauti; Stefánsson, Einar; Loftsson, Thorsteinn

    2016-01-01

    Ocular drug delivery to the posterior segment of the eye can be accomplished by invasive drug injections into different tissues of the eye and noninvasive topical treatment. Invasive treatment involves the risks of surgical trauma and infection, and conventional topical treatments are ineffective in delivering drugs to the posterior segment of the eye. In recent years, nanotechnology has become an ever-increasing part of ocular drug delivery. In the following, we briefly review microspheres and nanotechnology for drug delivery to the eye, including different forms of nanotechnology such as nanoparticles, microparticles, liposomes, microemulsions and micromachines. The permeation barriers and anatomical considerations linked to ocular drug delivery are discussed and a theoretical overview on drug delivery through biological membranes is given. Finally, in vitro, in vivo and human studies of x03B3;-cyclodextrin nanoparticle eyedrop suspensions are discussed as an example of nanotechnology used for drug delivery to the eye. PMID:26501994

  1. Microspheres and Nanotechnology for Drug Delivery.

    PubMed

    Jóhannesson, Gauti; Stefánsson, Einar; Loftsson, Thorsteinn

    2016-01-01

    Ocular drug delivery to the posterior segment of the eye can be accomplished by invasive drug injections into different tissues of the eye and noninvasive topical treatment. Invasive treatment involves the risks of surgical trauma and infection, and conventional topical treatments are ineffective in delivering drugs to the posterior segment of the eye. In recent years, nanotechnology has become an ever-increasing part of ocular drug delivery. In the following, we briefly review microspheres and nanotechnology for drug delivery to the eye, including different forms of nanotechnology such as nanoparticles, microparticles, liposomes, microemulsions and micromachines. The permeation barriers and anatomical considerations linked to ocular drug delivery are discussed and a theoretical overview on drug delivery through biological membranes is given. Finally, in vitro, in vivo and human studies of x03B3;-cyclodextrin nanoparticle eyedrop suspensions are discussed as an example of nanotechnology used for drug delivery to the eye.

  2. Chitosan Microspheres in Novel Drug Delivery Systems

    PubMed Central

    Mitra, Analava; Dey, Baishakhi

    2011-01-01

    The main aim in the drug therapy of any disease is to attain the desired therapeutic concentration of the drug in plasma or at the site of action and maintain it for the entire duration of treatment. A drug on being used in conventional dosage forms leads to unavoidable fluctuations in the drug concentration leading to under medication or overmedication and increased frequency of dose administration as well as poor patient compliance. To minimize drug degradation and loss, to prevent harmful side effects and to increase drug bioavailability various drug delivery and drug targeting systems are currently under development. Handling the treatment of severe disease conditions has necessitated the development of innovative ideas to modify drug delivery techniques. Drug targeting means delivery of the drug-loaded system to the site of interest. Drug carrier systems include polymers, micelles, microcapsules, liposomes and lipoproteins to name some. Different polymer carriers exert different effects on drug delivery. Synthetic polymers are usually non-biocompatible, non-biodegradable and expensive. Natural polymers such as chitin and chitosan are devoid of such problems. Chitosan comes from the deacetylation of chitin, a natural biopolymer originating from crustacean shells. Chitosan is a biocompatible, biodegradable, and nontoxic natural polymer with excellent film-forming ability. Being of cationic character, chitosan is able to react with polyanions giving rise to polyelectrolyte complexes. Hence chitosan has become a promising natural polymer for the preparation of microspheres/nanospheres and microcapsules. The techniques employed to microencapsulate with chitosan include ionotropic gelation, spray drying, emulsion phase separation, simple and complex coacervation. This review focuses on the preparation, characterization of chitosan microspheres and their role in novel drug delivery systems. PMID:22707817

  3. Microsphere size influences the foreign body reaction.

    PubMed

    Zandstra, J; Hiemstra, C; Petersen, A H; Zuidema, J; van Beuge, M M; Rodriguez, S; Lathuile, A A; Veldhuis, G J; Steendam, R; Bank, R A; Popa, E R

    2014-01-01

    Biodegradable poly-(DL-lactide-co-glycolide) (PLGA) microspheres (MSP) are attractive candidate vehicles for site-specific or systemic sustained release of therapeutic compounds. This release may be altered by the host's foreign body reaction (FBR), which is dependent on the characteristics of the implant, e.g. chemistry, shape or size. In this study, we focused on the characterisation of the influence of MSP size on the FBR. To this end we injected monodisperse MSP of defined size (small 5.8 µm, coefficient of variance (CV) 14 % and large 29.8 µm, CV 4 %) and polydisperse MSP (average diameter 34.1 µm, CV 51 %) under the skin of rats. MSP implants were retrieved at day 7, 14 and 28 after transplantation. The FBR was studied in terms of macrophage infiltration, implant encapsulation, vascularisation and extracellular matrix deposition. Although PLGA MSP of all different sizes demonstrated excellent in vitro and in vivo biocompatibility, significant differences were found in the characteristics of the FBR. Small MSP were phagocytosed, while large MSP were not. Large MSP occasionally elicited giant cell formation, which was not observed after implantation of small MSP. Cellular and macrophage influx and collagen deposition were increased in small MSP implants compared to large MSP. We conclude that the MSP size influences the FBR and thus might influence clinical outcome when using MSP as a drug delivery device. We propose that a rational choice of MSP size can aid in optimising the therapeutic efficacy of microsphere-based therapies in vivo. PMID:25350249

  4. Cerebral venous sinus thrombosis

    PubMed Central

    Allroggen, H.; Abbott, R.

    2000-01-01

    Cerebral venous sinus thrombosis is a challenging condition because of its variability of clinical symptoms and signs. It is very often unrecognised at initial presentation. All age groups can be affected. Large sinuses such as the superior sagittal sinus are most frequently involved. Extensive collateral circulation within the cerebral venous system allows for a significant degree of compensation in the early stages of thrombus formation. Systemic inflammatory diseases and inherited as well as acquired coagulation disorders are frequent causes, although in up to 30% of cases no underlying cause can be identified. The oral contraceptive pill appears to be an important additional risk factor. The spectrum of clinical presentations ranges from headache with papilloedema to focal deficit, seizures and coma. Magnetic resonance imaging with venography is the investigation of choice; computed tomography alone will miss a significant number of cases. It has now been conclusively shown that intravenous heparin is the first-line treatment for cerebral venous sinus thrombosis because of its efficacy, safety and feasability. Local thrombolysis may be indicated in cases of deterioration, despite adequate heparinisation. This should be followed by oral anticoagulation for 3-6 months. The prognosis of cerebral venous sinus thrombosis is generally favourable. A high index of clinical suspicion is needed to diagnose this uncommon condition so that appropriate treatment can be initiated.


Keywords: cerebral venous sinus thrombosis PMID:10622773

  5. A modular, plasmin-sensitive, clickable poly(ethylene glycol)-heparin-laminin microsphere system for establishing growth factor gradients in nerve guidance conduits.

    PubMed

    Roam, Jacob L; Yan, Ying; Nguyen, Peter K; Kinstlinger, Ian S; Leuchter, Michael K; Hunter, Daniel A; Wood, Matthew D; Elbert, Donald L

    2015-12-01

    Peripheral nerve regeneration is a complex problem that, despite many advancements and innovations, still has sub-optimal outcomes. Compared to biologically derived acellular nerve grafts and autografts, completely synthetic nerve guidance conduits (NGC), which allow for precise engineering of their properties, are promising but still far from optimal. We have developed an almost entirely synthetic NGC that allows control of soluble growth factor delivery kinetics, cell-initiated degradability and cell attachment. We have focused on the spatial patterning of glial-cell derived human neurotrophic factor (GDNF), which promotes motor axon extension. The base scaffolds consisted of heparin-containing poly(ethylene glycol) (PEG) microspheres. The modular microsphere format greatly simplifies the formation of concentration gradients of reversibly bound GDNF. To facilitate axon extension, we engineered the microspheres with tunable plasmin degradability. 'Click' cross-linking chemistries were also added to allow scaffold formation without risk of covalently coupling the growth factor to the scaffold. Cell adhesion was promoted by covalently bound laminin. GDNF that was released from these microspheres was confirmed to retain its activity. Graded scaffolds were formed inside silicone conduits using 3D-printed holders. The fully formed NGC's contained plasmin-degradable PEG/heparin scaffolds that developed linear gradients in reversibly bound GDNF. The NGC's were implanted into rats with severed sciatic nerves to confirm in vivo degradability and lack of a major foreign body response. The NGC's also promoted robust axonal regeneration into the conduit.

  6. A modular, plasmin-sensitive, clickable poly(ethylene glycol)-heparin-laminin microsphere system for establishing growth factor gradients in nerve guidance conduits.

    PubMed

    Roam, Jacob L; Yan, Ying; Nguyen, Peter K; Kinstlinger, Ian S; Leuchter, Michael K; Hunter, Daniel A; Wood, Matthew D; Elbert, Donald L

    2015-12-01

    Peripheral nerve regeneration is a complex problem that, despite many advancements and innovations, still has sub-optimal outcomes. Compared to biologically derived acellular nerve grafts and autografts, completely synthetic nerve guidance conduits (NGC), which allow for precise engineering of their properties, are promising but still far from optimal. We have developed an almost entirely synthetic NGC that allows control of soluble growth factor delivery kinetics, cell-initiated degradability and cell attachment. We have focused on the spatial patterning of glial-cell derived human neurotrophic factor (GDNF), which promotes motor axon extension. The base scaffolds consisted of heparin-containing poly(ethylene glycol) (PEG) microspheres. The modular microsphere format greatly simplifies the formation of concentration gradients of reversibly bound GDNF. To facilitate axon extension, we engineered the microspheres with tunable plasmin degradability. 'Click' cross-linking chemistries were also added to allow scaffold formation without risk of covalently coupling the growth factor to the scaffold. Cell adhesion was promoted by covalently bound laminin. GDNF that was released from these microspheres was confirmed to retain its activity. Graded scaffolds were formed inside silicone conduits using 3D-printed holders. The fully formed NGC's contained plasmin-degradable PEG/heparin scaffolds that developed linear gradients in reversibly bound GDNF. The NGC's were implanted into rats with severed sciatic nerves to confirm in vivo degradability and lack of a major foreign body response. The NGC's also promoted robust axonal regeneration into the conduit. PMID:26352518

  7. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, Myles A.; Morris, Robert S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.

  8. Magnetic cellulose-derivative structures

    DOEpatents

    Walsh, M.A.; Morris, R.S.

    1986-09-16

    Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorption agents can be incorporated during the manufacture of the structure. 3 figs.

  9. Cerebral phaeohyphomycosis by Exophiala dermatitidis.

    PubMed

    Sood, S; Vaid, V K; Sharma, M; Bhartiya, H

    2014-01-01

    Cerebral phaeohyphomycosis is a rare and frequently fatal disease. We report a case of cerebral phaeohyphomycosis caused by Exophiala dermatitidis in a young immuno competent male presenting to a tertiary care hospital in Jaipur. PMID:24713913

  10. Characteristics of dynamic cerebral autoregulation in cerebral small vessel disease: Diffuse and sustained.

    PubMed

    Guo, Zhen-Ni; Xing, Yingqi; Wang, Shuang; Ma, Hongyin; Liu, Jia; Yang, Yi

    2015-01-01

    Cerebral small vessel disease is a major cause of stroke and vascular dementia; however, the pathogenesis is largely unclear. In this study, we investigated the characteristics of the impairment of dynamic cerebral autoregulation (dCA) in lacunar infarction patients. Seventy-one lacunar infarction patients were enrolled in the study, including 46 unilateral middle cerebral artery (MCA) territory stroke patients and 25 unilateral posterior cerebral artery (PCA) territory stroke patients. Each group of patients was randomly divided into two subgroups. Group 1 underwent dCA assessments in the bilateral MCAs, and Group 2 underwent dCA assessments in the bilateral PCAs. All patients were followed up for 6 months. Transfer function analysis was applied to derive the autoregulatory parameters of gain and phase difference. In the unilateral MCA territory stroke patients, impairments of dCA were observed in both the MCAs and PCAs, and the same results were observed in the unilateral PCA territory stroke patients. These impairments remained unchanged during the 6-month follow-up. In lacunar infarction, which is most prevalent type of cerebral small vessel disease, though patients with unilateral MCA territory/PCA territory stroke, the impairments of dCA were global and sustained. This finding suggests that the physiological changes associated with lacunar infarction were diffuse.

  11. Characteristics of dynamic cerebral autoregulation in cerebral small vessel disease: Diffuse and sustained

    PubMed Central

    Guo, Zhen-Ni; Xing, Yingqi; Wang, Shuang; Ma, Hongyin; Liu, Jia; Yang, Yi

    2015-01-01

    Cerebral small vessel disease is a major cause of stroke and vascular dementia; however, the pathogenesis is largely unclear. In this study, we investigated the characteristics of the impairment of dynamic cerebral autoregulation (dCA) in lacunar infarction patients. Seventy-one lacunar infarction patients were enrolled in the study, including 46 unilateral middle cerebral artery (MCA) territory stroke patients and 25 unilateral posterior cerebral artery (PCA) territory stroke patients. Each group of patients was randomly divided into two subgroups. Group 1 underwent dCA assessments in the bilateral MCAs, and Group 2 underwent dCA assessments in the bilateral PCAs. All patients were followed up for 6 months. Transfer function analysis was applied to derive the autoregulatory parameters of gain and phase difference. In the unilateral MCA territory stroke patients, impairments of dCA were observed in both the MCAs and PCAs, and the same results were observed in the unilateral PCA territory stroke patients. These impairments remained unchanged during the 6-month follow-up. In lacunar infarction, which is most prevalent type of cerebral small vessel disease, though patients with unilateral MCA territory/PCA territory stroke, the impairments of dCA were global and sustained. This finding suggests that the physiological changes associated with lacunar infarction were diffuse. PMID:26469343

  12. Effect of surface roughness of chitosan-based microspheres on cell adhesion

    NASA Astrophysics Data System (ADS)

    Zan, Qingfeng; Wang, Chen; Dong, Limin; Cheng, Peng; Tian, Jiemo

    2008-11-01

    Microspheres are novel candidate materials for microcarriers and tissue-engineering scaffolds. Chitosan microspheres were selected as the base materials because of their excellent properties for biomedical applications. But their smooth surfaces were not adapted for cell attachment. Hence, in order to improve the roughness of chitosan microspheres, β-TCP/chitosan composite microspheres were developed. From SEM photographs, the coarse surfaces of composite microspheres were observed, there were some ceramic particles standing out of the chitosan matrix. And their roughness measured by profilometers was about 2.0 μm. Mouse MC3T3-E1 osteoblasts were seeded on the microspheres for evaluating the attachment interaction between cells and materials. According to the ESEM photographs and MTT assay, the adherence and proliferation of osteoblasts on the surfaces of modified microspheres were better than those on the chitosan microspheres, which were mainly attributed to the improved roughness of surface.

  13. Preparation of polysulfone hollow microspheres encapsulating DNA and their functional utilization.

    PubMed

    Zhao, C; Liu, X D; Nomizu, M; Nishi, N

    2004-05-01

    Polysulfone hollow microspheres encapsulating DNA were prepared using a liquid-liquid phase separation technique. The microspheres were then used to absorb a DNA-binding intercalating material--ethidium bromide. The amount of DNA encapsulated in the microspheres depended on the concentration of the DNA solution used to prepare the microspheres, and the microsphere morphology depended on both the polymer concentration and the preparation conditions. The amount of ethidium bromide in the microspheres depended mainly on the amount of encapsulated DNA, and the microsphere morphology also affected the removal of the ethidium bromide. The new method of DNA encapsulation is proposed, and the microspheres encapsulating the DNA have the potential to be used in environmental applications.

  14. Encapsulation of catalase in polyelectrolyte microspheres composed of melamine formaldehyde, dextran sulfate, and protamine.

    PubMed

    Balabushevich, N G; Zimina, E P; Larionova, N I

    2004-07-01

    Immobilization of catalase (molecular weight 240,000 daltons) in polyelectrolyte microspheres was studied. The microspheres were obtained by alternating adsorption of dextran sulfate and protamine on commercially available melamine formaldehyde cores followed by the core hydrolysis at pH 1.7. As the interior of the microspheres was filled with homogeneous matrix, the catalase distribution inside the microspheres was uniform. The quantity of entrapped catalase was dependent on the initial concentration of the enzyme and pH of solution, and the peak value was 10(8)-10(9) molecules per microsphere. It was demonstrated that catalase was entrapped in the microspheres via electrostatic and hydrophobic interactions. The catalase activity inside the microspheres increased as the quantity of enzyme decreased, which was due to the switch between diffusion and kinetic regimes of the enzymatic reaction. The microspheres could be applied for separation and concentration of high molecular weight proteins.

  15. Apparatus for washing particulate material. [Removal of silicone oil from microspheres by trichloroethylene

    DOEpatents

    Rivera, A.L.; Fowler, V.L.; Justice, G.V.

    1983-12-29

    Transport of nuclear fuel microspheres through a wash liquid is facilitated by feeding a slurry containing the microspheres into the wash liquid via a column having a vibrating tubular screen located under its lower end.

  16. Membranes for specific adsorption: immobilizing molecularly imprinted polymer microspheres using electrospun nanofibers.

    PubMed

    Büttiker, Roman; Ebert, Jürgen; Hinderling, Christian; Adlhart, Christian

    2011-01-01

    Molecularly imprinted polymer microspheres were immobilized within a polymer nanofiber membrane by electrospinning. Such membranes simplify the handling of functional microspheres and provide specific recognition capabilities for solid-phase extraction and filtration applications. In this study, microspheres were prepared by precipitation polymerization of methacrylic acid and divinylbenzene as a cross-linker with the target molecule (-)-cinchonidine and then, they were electrospun into a non-woven polyacrylonitrile nanofiber membrane. The composite membrane showed specific affinity for (-)-cinchonidine which was attributed to the functional microspheres as confirmed by Raman microscopy. The target molecule capturing capacity of the composite membrane was 5 mg/g or 25 mg/g immobilized functional microsphere. No difference in target affinity was observed between the immobilized microspheres and the free microspheres. These results reveal that electrospun composite membranes are a feasible approach to immobilizing functional microspheres.

  17. Membranes for specific adsorption: immobilizing molecularly imprinted polymer microspheres using electrospun nanofibers.

    PubMed

    Büttiker, Roman; Ebert, Jürgen; Hinderling, Christian; Adlhart, Christian

    2011-01-01

    Molecularly imprinted polymer microspheres were immobilized within a polymer nanofiber membrane by electrospinning. Such membranes simplify the handling of functional microspheres and provide specific recognition capabilities for solid-phase extraction and filtration applications. In this study, microspheres were prepared by precipitation polymerization of methacrylic acid and divinylbenzene as a cross-linker with the target molecule (-)-cinchonidine and then, they were electrospun into a non-woven polyacrylonitrile nanofiber membrane. The composite membrane showed specific affinity for (-)-cinchonidine which was attributed to the functional microspheres as confirmed by Raman microscopy. The target molecule capturing capacity of the composite membrane was 5 mg/g or 25 mg/g immobilized functional microsphere. No difference in target affinity was observed between the immobilized microspheres and the free microspheres. These results reveal that electrospun composite membranes are a feasible approach to immobilizing functional microspheres. PMID:21528654

  18. Mineralization, biodegradation, and drug release behavior of gelatin/apatite composite microspheres for bone regeneration.

    PubMed

    Leeuwenburgh, Sander C G; Jo, Junichiro; Wang, Huanan; Yamamoto, Masaya; Jansen, John A; Tabata, Yasuhiko

    2010-10-11

    Gelatin microspheres are well-known for their capacity to release growth factors in a controlled manner, but gelatin microspheres do not calcify in the absence of so-called bioactive substances that induce deposition of calcium phosphate (CaP) bone mineral. This study has investigated if CaP nanocrystals can be incorporated into gelatin microspheres to render these inert microspheres bioactive without compromising the drug releasing properties of gelatin microspheres. Incorporation of CaP nanocrystals into gelatin microspheres resulted into reduced biodegradation and drug release rates, whereas their calcifying capacity increased strongly compared to inert gelatin microspheres. The reduced drug release rate was correlated to the reduced degradation rate as caused by a physical cross-linking effect of CaP nanocrystals dispersed in the gelatin matrix. Consequently, these composite microspheres combine beneficial drug-releasing properties of organic gelatin with the calcifying capacity of a dispersed CaP phase. PMID:20804200

  19. Neuroprotection after cerebral ischemia

    PubMed Central

    Namura, Shobu; Ooboshi, Hiroaki; Liu, Jialing; Yenari, Midori A.

    2013-01-01

    Cerebral ischemia, a focal or global insufficiency of blood flow to the brain, can arise through multiple mechanisms, including thrombosis and arterial hemorrhage. Ischemia is a major driver of stroke, one of the leading causes of morbidity and mortality worldwide. While the general etiology of cerebral ischemia and stroke has been known for some time, the conditions have only recently been considered treatable. This report describes current research in this field seeking to fully understand the pathomechanisms underlying stroke; to characterize the brain’s intrinsic injury, survival, and repair mechanisms; to identify putative drug targets as well as cell-based therapies; and to optimize the delivery of therapeutic agents to the damaged cerebral tissue. PMID:23488559

  20. Effects of raised intracranial pressure on regional cerebral blood flow: a comparison of effects of naloxone and TRH on the microcirculation in partial cerebral ischaemia.

    PubMed Central

    Koskinen, L. O.

    1985-01-01

    The effects on regional cerebral blood flow (rCBF) of raised intracranial pressure (ICP) and of naloxone and thyrotropin releasing hormone (TRH) during this condition were studied in anaesthetized rabbits. The ICP was elevated until a central ischaemic response was observed. The regional blood flow was determined with the microsphere technique before and during elevation of the ICP (ICPe) and after drug treatment. Total CBF was reduced by about 70% during ICPe while the uveal blood flow increased slightly and some other peripheral tissue blood flows remained unaffected. The administration of TRH caused an increase in mean arterial blood pressure (MAP) from 11.9 +/- 0.6 to 14.6 +/- 0.7 kPa and a normalization of the rCBF. In some peripheral tissues, e.g. gastric mucosa and spleen, TRH reduced the blood flow by 53% and 76%, respectively. In blood pressure stabilized animals no effect on rCBF was seen after TRH. Naloxone had no consistent effect on MAP or local blood flow. It was concluded that in the range of cerebral perfusion pressure studied there was a passive relationship between cerebral blood flow and perfusion pressure. The lack of effect of naloxone and the marked effect of TRH during cerebral ischaemia are consistent with a mechanism of action of TRH not related to a 'physiological' antagonism of opioids. PMID:3928009

  1. Three dimensional confocal microscopy of fluorescent microspheres: imaging and size determination

    NASA Astrophysics Data System (ADS)

    Rakovich, Y. P.; Yang, L.; Taylor, C. M.; Dunbar, L. A.; Mac Raighne, Aaron; Donegan, J. F.; McCabe, Eithne M.

    2005-06-01

    In this paper, we experimentally studied both the bright-field and fluorescence images of microspheres by conventional and confocal scanning polarization microscopes. A qualitative analysis have been given to show a physical picture on the imaging of the microspheres. Emission spectra from melamine formaldehyde microspheres stained with Ethidium Bromide or covered by thin shell of CdTe nanocrystals have been experimentally studied. We adopted analytical expressions describing the resonance spacing in order to determine the size of the microspheres.

  2. Unusual Cerebral Emboli.

    PubMed

    Zakhari, Nader; Castillo, Mauricio; Torres, Carlos

    2016-02-01

    The heart and the carotid arteries are the most common sites of origin of embolic disease to the brain. Clots arising from these locations are the most common types of brain emboli. Less common cerebral emboli include air, fat, calcium, infected vegetations, and tumor cells as well as emboli originating in the venous system. Although infarcts can be the final result of any type of embolism, described herein are the ancillary and sometimes unique imaging features of less common types of cerebral emboli that may allow for a specific diagnosis to be made or at least suspected in many patients.

  3. Formulation and in vitro evaluation of rifampicin loaded porous microspheres.

    PubMed

    Bhise, Satish Balakrishna; More, Avinash Bhanudas; Malayandi, Rajkumar

    2010-01-01

    Rifampicin (RIF) is a major component in fixed dose combination therapy for the treatment of tuberculosis. RIF has low solubility and high permeability with high dose and hence it is classified as class II drug in Biopharmaceutical Classification System (BCS). RIF has poor and variable bioavailability because of its poor solubility, acid decomposition and, drug and food interaction. The present investigation was aimed to develop RIF loaded porous microspheres as a controlled release dosage form. Eudragit based porous microspheres of RIF were prepared by emulsion solvent diffusion method. Prepared porous microspheres were evaluated for its entrapment efficacy, morphology, thermal behavior, crystalline nature, in-vitro drug release and stability in simulated gastric fluid. The entrapment efficacy of drug loaded microspheres was found to be in the range of 19.04â74.57%. Surface morphology revealed the porous and spherical structure of microspheres. Differential scanning calorimetric studies confirmed that formulation process altered the crystalline nature of RIF. In vitro drug release studies indicated that drug to polymer ratio of 2:1 showed more than 85% drug release over the period of 3 h. Stability studies in simulated gastric fluid (SGF) indicated that low relative decomposition of 18.5% was achieved with high drug to low polymer ratio of 1:4. The results obtained from the present investigation concluded that RIF loaded porous microspheres are suitable for developing oral controlled release dosage form of RIF that can prevent acid decomposition and provide better biopharmaceutical properties. Further more the microspheres can be evaluated for preventing the interaction with isoniazid, other drugs and foodstuffs.

  4. A novel strategy for the preparation of porous microspheres and its application in peptide drug loading.

    PubMed

    Wei, Yi; Wang, Yuxia; Zhang, Huixia; Zhou, Weiqing; Ma, Guanghui

    2016-09-15

    A new strategy is developed to prepare porous microspheres with narrow size distribution for peptides controlled release, involving a fabrication of porous microspheres without any porogens followed by a pore closing process. Amphiphilic polymers with different hydrophobic segments (poly(monomethoxypolyethylene glycol-co-d,l-lactide) (mPEG-PLA), poly(monomethoxypolyethylene glycol-co-d,l-lactic-co-glycolic acid) (mPEG-PLGA)) are employed as microspheres matrix to prepare porous microspheres based on a double emulsion-premix membrane emulsification technique combined with a solvent evaporation method. Both microspheres possess narrow size distribution and porous surface, which are mainly caused by (a) hydrophilic polyethylene glycol (PEG) segments absorbing water molecules followed by a water evaporation process and (b) local explosion of microspheres due to fast evaporation of dichloromethane (MC). Importantly, mPEG-PLGA microspheres have a honeycomb like structure while mPEG-PLA microspheres have a solid structure internally, illustrating that the different hydrophobic segments could modulate the affinity between solvent and matrix polymer and influence the phase separation rate of microspheres matrix. Long term release patterns are demonstrated with pore-closed microspheres, which are prepared from mPEG-PLGA microspheres loading salmon calcitonin (SCT). These results suggest that it is potential to construct porous microspheres for drug sustained release using permanent geometric templates as new porogens. PMID:27285778

  5. A novel strategy for the preparation of porous microspheres and its application in peptide drug loading.

    PubMed

    Wei, Yi; Wang, Yuxia; Zhang, Huixia; Zhou, Weiqing; Ma, Guanghui

    2016-09-15

    A new strategy is developed to prepare porous microspheres with narrow size distribution for peptides controlled release, involving a fabrication of porous microspheres without any porogens followed by a pore closing process. Amphiphilic polymers with different hydrophobic segments (poly(monomethoxypolyethylene glycol-co-d,l-lactide) (mPEG-PLA), poly(monomethoxypolyethylene glycol-co-d,l-lactic-co-glycolic acid) (mPEG-PLGA)) are employed as microspheres matrix to prepare porous microspheres based on a double emulsion-premix membrane emulsification technique combined with a solvent evaporation method. Both microspheres possess narrow size distribution and porous surface, which are mainly caused by (a) hydrophilic polyethylene glycol (PEG) segments absorbing water molecules followed by a water evaporation process and (b) local explosion of microspheres due to fast evaporation of dichloromethane (MC). Importantly, mPEG-PLGA microspheres have a honeycomb like structure while mPEG-PLA microspheres have a solid structure internally, illustrating that the different hydrophobic segments could modulate the affinity between solvent and matrix polymer and influence the phase separation rate of microspheres matrix. Long term release patterns are demonstrated with pore-closed microspheres, which are prepared from mPEG-PLGA microspheres loading salmon calcitonin (SCT). These results suggest that it is potential to construct porous microspheres for drug sustained release using permanent geometric templates as new porogens.

  6. In situ growth of copper nanocrystals from carbonaceous microspheres with electrochemical glucose sensing properties

    SciTech Connect

    Zhou, Xiaoliang; Yan, Zhengguang Han, Xiaodong

    2014-02-01

    Graphical abstract: In situ growth of copper nanoparticles from hydrothermal copper-containing carbonaceous microspheres was induced by annealing or electron beam irradiation. Obtained micro-nano carbon/copper composite microspheres show electrochemical glucose sensing properties. - Highlights: • We synthesized carbonaceous microspheres containing non-nanoparicle copper species through a hydrothermal route. • By annealing or electron beam irradiation, copper nanoparticles would form from the carbonaceous microspheres in situ. • By controlling the annealing temperature, particle size of copper could be controlled in the range of 50–500 nm. • The annealed carbon/copper hierarchical composite microspheres were used to fabricate an electrochemical glucose sensor. - Abstract: In situ growth of copper nanocrystals from carbon/copper microspheres was observed in a well-controlled annealing or an electron beam irradiation process. Carbonaceous microspheres containing copper species with a smooth appearance were yielded by a hydrothermal synthesis using copper nitrate and ascorbic acid as reactants. When annealing the carbonaceous microspheres under inert atmosphere, copper nanoparticles were formed on carbon microspheres and the copper particle sizes can be increased to a range of 50–500 nm by altering the heating temperature. Similarly, in situ formation of copper nanocrystals from these carbonaceous microspheres was observed on the hydrothermal product carbonaceous microspheres with electron beam irradiation in a vacuum transmission electron microscopy chamber. The carbon/copper composite microspheres obtained through annealing were used to modify a glassy carbon electrode and tested as an electrochemical glucose sensor.

  7. Mixed uranium dicarbide and uranium dioxide microspheres and process of making same

    DOEpatents

    Stinton, David P.

    1983-01-01

    Nuclear fuel microspheres are made by sintering microspheres containing uranium dioxide and uncombined carbon in a 1 mole percent carbon monoxide/99 mole percent argon atmosphere at 1550.degree. C. and then sintering the microspheres in a 3 mole percent carbon monoxide/97 mole percent argon atmosphere at the same temperature.

  8. Stem cell therapy: a novel treatment option for cerebral malaria?

    PubMed

    Wang, Wei; Qian, Hui; Cao, Jun

    2015-01-01

    Cerebral malaria, a severe form of the disease, is one of the most severe complications of infection with Plasmodium parasites and a leading cause of malaria mortality. Currently available antimalarial therapy has proven insufficient to prevent neurological complications and death in all cases of cerebral malaria. Souza and colleagues observed that transplantation of bone marrow-derived mesenchymal stromal cells (BM-MSCs) increased survival, reduced parasitemia, decreased malaria pigment accumulation in the spleen, liver and kidney, elevated Kupffer cell count in liver, alleviated renal injury and lung inflammation, and improved lung mechanics in an experimental mouse model of cerebral malaria. Although plenty of challenges lie ahead, their findings show the promise of BM-MSC therapy for the treatment of cerebral malaria. PMID:26253514

  9. Cerebral Folate Deficiency

    ERIC Educational Resources Information Center

    Gordon, Neil

    2009-01-01

    Cerebral folate deficiency (CFD) is associated with low levels of 5-methyltetrahydrofolate in the cerebrospinal fluid (CSF) with normal folate levels in the plasma and red blood cells. The onset of symptoms caused by the deficiency of folates in the brain is at around 4 to 6 months of age. This is followed by delayed development, with deceleration…

  10. Cerebral Palsy Litigation

    PubMed Central

    Sartwelle, Thomas P.

    2015-01-01

    The cardinal driver of cerebral palsy litigation is electronic fetal monitoring, which has continued unabated for 40 years. Electronic fetal monitoring, however, is based on 19th-century childbirth myths, a virtually nonexistent scientific foundation, and has a false positive rate exceeding 99%. It has not affected the incidence of cerebral palsy. Electronic fetal monitoring has, however, increased the cesarian section rate, with the expected increase in mortality and morbidity risks to mothers and babies alike. This article explains why electronic fetal monitoring remains endorsed as efficacious in the worlds’ labor rooms and courtrooms despite being such a feeble medical modality. It also reviews the reasons professional organizations have failed to condemn the use of electronic fetal monitoring in courtrooms. The failures of tort reform, special cerebral palsy courts, and damage limits to stem the escalating litigation are discussed. Finally, the authors propose using a currently available evidence rule—the Daubert doctrine that excludes “junk science” from the courtroom—as the beginning of the end to cerebral palsy litigation and electronic fetal monitoring’s 40-year masquerade as science. PMID:25183322

  11. Thermal expansion of an epoxy-glass microsphere composite

    NASA Technical Reports Server (NTRS)

    Price, H. L.; Burks, H. D.

    1977-01-01

    The thermal expansion of a composite of epoxy (diglycidyl ether of bisphenol A) and solid glass microspheres was investigated. The microspheres had surfaces which were either untreated or treated with a silicone release agent, an epoxy coupling agent, or a general purpose silane coupling agent. Both room temperature (about 300 K) and elevated temperature (about 475 K) cures were used for the epoxy. Two microsphere size ranges were used, about 50 microns, which is applicable in filled moldings, and about 125 microns, which is applicable as bond line spacers. The thermal expansion of the composites was measured from 300 to 350 K or from 300 to 500 K, depending on the epoxy cure temperature. Measurements were made on composites containing up to .6 volume fraction microspheres. Two predictive models, which required only the values of thermal expansion of the polymer and glass and their specific gravities, were tested against the experimental data. A finite element analysis was made of the thermal strain of a composite cell containing a single microsphere surrounded by a finite-thickness interface.

  12. Iron Nanoparticles-Encapsulating Silica Microspheres for Arterial Embolization Hyperthermia

    NASA Astrophysics Data System (ADS)

    Li, Z.; Kawashita, M.

    2011-10-01

    We attempted to prepare α-Fe-encapsulating silica (αFeSi) microspheres by a sol-gel process using tetramethoxysilane (TMOS) in water-in-oil emulsion. The effect of preparation conditions on the structure, magnetic and heating properties of resultant products were investigated. Oil phase consisted of kerosene with 32 wt% of surfactants (sorbitan monooleate / sorbitan monostearate in 3:1 weight ratio). Water phase consisted of TMOS, ethanol (CH2CH3OH), water and iron nitrate (Fe(NO3)3·9H2O) with TMOS / CH2CH3OH/H2O/Fe3+ in 1:7.4:16.2:0.4~1.2 molar ratio. Fe3+-containing silica gel (FeSiG) microspheres 5 to 30 μm in size were successfully obtained by adding the water phase into the oil phase at 60 °C under stirring of 1500 rpm for 100 min. αFeSi microspheres was obtained by heating the FeSiG microspheres at 850°C in argon atmosphere. The obtained αFeSi microspheres have a saturation magnetization (Ms) up to 21 emu g-1 and a coercive force (Hc) of 133 Oe. The in vitro heating generation was evaluated under an alternating current (AC) magnetic field of 300 Oe and 100 kHz.

  13. Modelling heating of liver tumours with heterogeneous magnetic microsphere deposition.

    PubMed

    Tsafnat, N; Tsafnat, G; Lambert, T D; Jones, S K

    2005-06-21

    Ferromagnetic embolization hyperthermia (FEH) is a novel treatment for liver cancer. Magnetic microspheres are injected into the hepatic artery and cluster in the periphery of tumours and are heated with externally applied magnetic fields. In order to more accurately simulate FEH, we modelled a three-dimensional heterogeneous distribution of heat sources. We constructed a fractal model of the vasculature in the periphery of a tumour. We used this model to compute the spatial distribution of the microspheres that lodge in capillaries. We used the distribution model as input to a finite-element heat transfer model of the FEH treatment. The overall appearance of the vascular tree is subjectively similar to that of the disorganized vascular network which encapsulates tumours. The microspheres are distributed in the tumour periphery in similar patterns to experimental observations. We expect the vasculature and microsphere deposition models to also be of interest to researchers of any targeted cancer therapies such as localized intra-arterial chemotherapy and selective internal radiotherapy. Our results show that heterogeneous microsphere distributions give significantly different results to those for a homogeneous model and thus are preferable when accurate results are required.

  14. Modelling heating of liver tumours with heterogeneous magnetic microsphere deposition

    NASA Astrophysics Data System (ADS)

    Tsafnat, N.; Tsafnat, G.; Lambert, T. D.; Jones, S. K.

    2005-06-01

    Ferromagnetic embolization hyperthermia (FEH) is a novel treatment for liver cancer. Magnetic microspheres are injected into the hepatic artery and cluster in the periphery of tumours and are heated with externally applied magnetic fields. In order to more accurately simulate FEH, we modelled a three-dimensional heterogeneous distribution of heat sources. We constructed a fractal model of the vasculature in the periphery of a tumour. We used this model to compute the spatial distribution of the microspheres that lodge in capillaries. We used the distribution model as input to a finite-element heat transfer model of the FEH treatment. The overall appearance of the vascular tree is subjectively similar to that of the disorganized vascular network which encapsulates tumours. The microspheres are distributed in the tumour periphery in similar patterns to experimental observations. We expect the vasculature and microsphere deposition models to also be of interest to researchers of any targeted cancer therapies such as localized intra-arterial chemotherapy and selective internal radiotherapy. Our results show that heterogeneous microsphere distributions give significantly different results to those for a homogeneous model and thus are preferable when accurate results are required.

  15. Controlling silk fibroin microspheres via molecular weight distribution.

    PubMed

    Zeng, Dong-Mei; Pan, Jue-Jing; Wang, Qun; Liu, Xin-Fang; Wang, Hui; Zhang, Ke-Qin

    2015-05-01

    Silk fibroin (SF) microspheres were produced by salting out SF solution via the addition of potassium phosphate buffer solution (K2HPO4-KH2PO4). The morphology, size and polydispersity of SF microspheres were adjusted by changing the molecular weight (MW) distribution and concentration of SF, as well as the ionic strength and pH of the buffer solution. Changing the conditions under which the SF fiber dissolved in the Lithium Boride (LiBr) solution resulted in altering the MW distribution of SF solution. Under optimal salting-out conditions (ionic strength>0.7 M and pH>7) and using a smaller and narrower SF MW distribution, SF microspheres with smoother shapes and more uniform sizes were produced. Meanwhile, the size and polydispersity of the microspheres increased when the SF concentration was increased from 0.25 mg/mL to 20 mg/mL. The improved SF microspheres, obtained by altering the distribution of molecular weight, have potential in drug and gene delivery applications.

  16. Poly(ester amide) blend microspheres for oral insulin delivery.

    PubMed

    He, Pan; Liu, Huaiyu; Tang, Zhaohui; Deng, Mingxiao; Yang, Yan; Pang, Xuan; Chen, Xuesi

    2013-10-15

    This study developed a novel oral insulin formulation centered on microspheres consisting of a blend of biodegradable poly(ester amide) (PEA). In the formulation, L-lysine-/L-leucine-based PEA with pendant COOH groups (PEA-COOH) was used as a pH-responsive material for the protection of insulin from the harsh environmental conditions of the stomach. Arginine-based PEA (Arg-PEA) was introduced to improve the intestinal absorption of the drug. The influence of both the hydrophobicity of PEA-COOH and the content of Arg-PEA was investigated in detail on microsphere surface morphology, drug loading, and the in vitro release profile of insulin. The PEA-COOH/Arg-PEA blend microspheres protected the loaded insulin in simulated gastric fluid and released insulin in a fast and sustained manner in simulated intestinal fluid. The in vivo test demonstrated that the oral administration of insulin-loaded PEA blend microspheres could effectively suppress the blood glucose level in diabetic rats for 10h, and the oral bioavailability was improved to 5.89+1.84% in healthy rats. These results indicate that the PEA blend microspheres are promising vehicles for the oral delivery of insulin.

  17. Pharmacodynamics of diclofenac from novel Eudragit entrapped microspheres.

    PubMed

    Momoh, M A; Kenechukwu, F C; Adedokun, M O; Odo, C E; Attama, A A

    2014-05-01

    Effective clinical utilization of non-steroidal anti-inflammatory drugs such as diclofenac sodium (DS) is significantly limited by their ulcerogenic potential and poor bioavailability after oral administration, thus necessitating the need for a better carrier to minimize these obvious limitations. The objective of this study was to evaluate Eudragit® RS100/RL100 microspheres formulated by the solvent-evaporation technique for improved delivery of diclofenac. Three batches of (DF1, DF2 and DF3) microspheres were prepared using different ratios of Eudragit RS-100 and RL-100 polymers based on the solvent-evaporation method. The microspheres were characterized based on morphological properties, particle size analysis and encapsulation efficiency (EE%). In vitro release of DS was investigated in both 0.1 N HCl (pH 1.2) and phosphate-buffered saline (pH 7.4), while anti-inflammatory studies were evaluated in the rat model. Maximum EE% of 86.61 ± 0.11, 88.14 ± 0.16 and 85.50 ± 0.21 was obtained for DF1, DF2 and DF3, respectively. Discrete, smooth and brownish microspheres of size range 437 ± 0.01-479 ± 0.21 µm were obtained. Release of DS from the formulation depends on the polymer ratio. All the batches exhibited good anti-inflammatory activities. Microsphere formulations based on Eudragit® polymers would likely offer a reliable and alternative means of delivering DS orally.

  18. RANKL delivery from calcium phosphate containing PLGA microspheres.

    PubMed

    Félix Lanao, Rosa P; Bosco, Ruggero; Leeuwenburgh, Sander C G; Kersten-Niessen, Monique J F; Wolke, Joop G C; van den Beucken, Jeroen J J P; Jansen, John A

    2013-11-01

    Ideally, bone substitute materials would undergo cell-mediated degradation during the remodeling process of the host bone tissue while being replaced by newly formed bone. In an attempt to exploit the capacity of Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL) to stimulate osteoclast-like cells formation, this study explored different loading methods for RANKL in injectable calcium phosphate cement (CPC) and the effect on release and biological activity. RANKL was loaded via the liquid phase of CPC by adsorption onto or incorporation into poly(lactic-co-glycolic acid) (PLGA) microspheres with two different morphologies (i.e., hollow and dense), which were subsequently embedded in CPC. As controls nonembedded PLGA-microspheres were used as well as plain CPC scaffolds with RANKL adsorbed onto the surface. RANKL release and activity were evaluated by Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) and osteoclast-like cells formation in cell culture experiments. Results indicated that sustained release of active RANKL can be achieved upon RANKL adsorption to PLGA microspheres, whereas inactive RANKL was released from CPC-PLGA formulations with RANKL incorporated within the microspheres or within the liquid phase of the CPC. These results demonstrate that effective loading of RANKL in injectable CPC is only possible via adsorption to PLGA microspheres, which are subsequently embedded within the CPC-matrix.

  19. Surface characterization by atomic force microscopy of sterilized PLGA microspheres.

    PubMed

    Dorati, Rossella; Patrini, Maddalena; Perugini, Paola; Pavanetto, Franca; Stella, Angiolino; Modena, Tiziana; Genta, Ida; Conti, Bice

    2006-03-01

    Atomic force microscopy (AFM) is recognized a suitable and powerful technique for surface and morphological analysis. Even if until now this technique has not been frequently used in the pharmaceutical field, it can contribute to an accurate morphologic characterization of microspheres and nanospheres. In this work, atomic force microscopy has been used to perform the surface characterization of sterilized microspheres. The aim is to investigate the morphologic modifications induced by gamma irradiation on poly(lactide-co-glycolide) microspheres loaded with ovalbumin and to compare the results obtained by AFM to those obtained by scanning electron microscopy (SEM). The results obtained show that, with respect to SEM, AFM can give some additional information regarding the modifications induced by gamma-irradiation on microspheres surface morphology. The significant changes in surface roughness after irradiation are indicative of damage due to gamma-irradiation. The unchanged surface roughness values calculated for microspheres containing PEG in their matrix, suggest that this polymer exerts a protective effect towards gamma-irradiation. PMID:16754370

  20. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    NASA Technical Reports Server (NTRS)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  1. Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates.

    PubMed

    Wei, Qingrong; Lu, Jian; Wang, Qiaoying; Fan, Hongsong; Zhang, Xingdong

    2015-03-20

    Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.

  2. Hierarchical {001}-faceted BiOBr microspheres as a novel biomimetic catalyst: dark catalysis towards colorimetric biosensing and pollutant degradation.

    PubMed

    Li, Lili; Ai, Lunhong; Zhang, Caihong; Jiang, Jing

    2014-05-01

    In recent years, considerable effort has been devoted to finding novel enzyme mimetics with improved catalytic activities. However, the insightful understanding of such catalytic process is still elusive. In this paper, we report for the first time a typical photoactive layer-structured BiOBr as a novel biomimetic catalyst possessing highly efficient intrinsic peroxidase-like activity. Moreover, we have experimentally achieved high dark peroxidase-like catalytic activity in BiOBr microspheres and provided some new insights into the light-enhanced peroxidase-like catalytic property. On the basis of a typical color reaction derived from catalytic oxidation of peroxidase substrates over BiOBr microspheres with H2O2, the simple and sensitive colorimetric assays for detection of H2O2, glucose and ascorbic acid were successfully established. More interestingly, the BiOBr microspheres showed strong ability towards activation of H2O2, displaying excellent dark catalytic activity for the degradation of organic dye. It is therefore believed that our findings in this study could open up the possibility of utilizing BiOBr as enzymatic mimics in biotechnology and environmental remediation. PMID:24637562

  3. Synthesis of hydrophilic intra-articular microspheres conjugated to ibuprofen and evaluation of anti-inflammatory activity on articular explants.

    PubMed

    Bédouet, Laurent; Moine, Laurence; Pascale, Florentina; Nguyen, Van-Nga; Labarre, Denis; Laurent, Alexandre

    2014-01-01

    The main limitation of current microspheres for intra-articular delivery of non-steroidal anti-inflammatory drugs (NSAIDs) is a significant initial burst release, which prevents a long-term drug delivery. In order to get a sustained delivery of NSAIDs without burst, hydrogel degradable microspheres were prepared by co-polymerization of a methacrylic derivative of ibuprofen with oligo(ethylene-glycol) methacrylate and poly(PLGA-PEG) dimethacrylate as degradable crosslinker. Microspheres (40-100 μm) gave a low yield of ibuprofen release in saline buffer (≈2% after 3 months). Mass spectrometry analysis confirmed that intact ibuprofen was regenerated indicating that ester hydrolysis occurred at the carboxylic acid position of ibuprofen. Dialysis of release medium followed by alkaline hydrolysis show that in saline buffer ester hydrolysis occurred at other positions in the polymer matrix leading to the release of water-soluble polymers (>6-8000 Da) conjugated with ibuprofen showing that degradation and drug release are simultaneous. By considering the free and conjugated ibuprofen, 13% of the drug is released in 3 months. In vitro, ibuprofen-loaded MS inhibited the synthesis of prostaglandin E2 in articular cartilage and capsule explants challenged with lipopolysaccharides. Covalent attachment of ibuprofen to PEG-hydrogel MS suppresses the burst release and allows a slow drug delivery for months and the cyclooxygenase-inhibition property of regenerated ibuprofen is preserved.

  4. Review: Cerebral microvascular pathology in aging and neurodegeneration

    PubMed Central

    Brown, William R.; Thore, Clara R.

    2010-01-01

    This review of age-related brain microvascular pathologies focuses on topics studied by this laboratory, including anatomy of the blood supply, tortuous vessels, venous collagenosis, capillary remnants, vascular density, and microembolic brain injury. Our studies feature thick sections, large blocks embedded in celloidin, and vascular staining by alkaline phosphatase (AP). This permits study of the vascular network in three dimensions, and the differentiation of afferent from efferent vessels. Current evidence suggests that there is decreased vascular density in aging, Alzheimer’s disease (AD), and leukoaraiosis (LA), and cerebrovascular dysfunction precedes and accompanies cognitive dysfunction and neurodegeneration. A decline in cerebrovascular angiogenesis may inhibit recovery from hypoxia-induced capillary loss. Cerebral blood flow (CBF) is inhibited by tortuous arterioles and deposition of excessive collagen in veins and venules. Misery perfusion due to capillary loss appears to occur before cell loss in LA, and CBF is also reduced in the normal-appearing white matter. Hypoperfusion occurs early in AD, inducing white matter lesions and correlating with dementia. In vascular dementia, cholinergic reductions are correlated with cognitive impairment, and cholinesterase inhibitors have some benefit. Most lipid microemboli from cardiac surgery pass through the brain in a few days, but some remain for weeks. They can cause what appears to be a type of vascular dementia years after surgery. Donepezil has shown some benefit. Emboli, such as clots, cholesterol crystals, and microspheres can be extruded through the walls of cerebral vessels, but there is no evidence yet that lipid emboli undergo such extravasation. PMID:20946471

  5. An in-vitro evaluation of three types of drug-eluting microspheres loaded with irinotecan.

    PubMed

    Pereira, Philippe L; Plotkin, Stephen; Yu, Renee; Sutter, Allison; Wu, Yue; Sommer, Christof M; Cruise, Gregory M

    2016-10-01

    To compare the mechanical and chemical properties of three commercially available microspheres loaded with irinotecan. LifePearl (200 µm), DC Bead (100-300 µm), and Tandem (100 µm) microspheres were loaded with irinotecan. For loading, elution, and stability determinations, irinotecan concentrations were quantified using validated high-performance liquid chromatography methods. In-vitro elution was performed over 24 h using a USP 4 dissolution apparatus. Diameter measurements were performed using light microscopy. Time in suspension was considered as the time required for the microspheres to vacate 1/3 of the volume. All three microsphere types rapidly loaded irinotecan, with more than 95% loading at 1 h. In-vitro elution of irinotecan was rapid for LifePearl and DC Bead microspheres, with more than 98% elution at 1 h, and delayed for Tandem microspheres, with about 70% elution at 6 h. After loading with irinotecan, the average diameter of LifePearl and DC Bead microspheres was reduced by 9 and 18%, respectively, and was unchanged for Tandem microspheres. All three microsphere types lost 4-6% of the loaded irinotecan almost immediately upon placement in contrast: water and contrast: 5% dextrose, but further losses were minimal over 2 weeks. LifePearl microspheres remained longer in suspension (392±23 s) compared with DC Bead (154±13 s, P<0.001) and Tandem (198±19 s, P<0.001) microspheres. All three microsphere types load irinotecan rapidly. LifePearl and DC Bead microspheres elute irinotecan rapidly. Elution is delayed with Tandem microspheres. LifePearl microspheres show the longest time in suspension. PMID:27416270

  6. Cerebral White Matter

    PubMed Central

    Schmahmann, Jeremy D.; Smith, Eric E.; Eichler, Florian S.; Filley, Christopher M.

    2013-01-01

    Lesions of the cerebral white matter (WM) result in focal neurobehavioral syndromes, neuropsychiatric phenomena, and dementia. The cerebral WM contains fiber pathways that convey axons linking cerebral cortical areas with each other and with subcortical structures, facilitating the distributed neural circuits that subserve sensorimotor function, intellect, and emotion. Recent neuroanatomical investigations reveal that these neural circuits are topographically linked by five groupings of fiber tracts emanating from every neocortical area: (1) cortico-cortical association fibers; (2) corticostriatal fibers; (3) commissural fibers; and cortico-subcortical pathways to (4) thalamus and (5) pontocerebellar system, brain stem, and/or spinal cord. Lesions of association fibers prevent communication between cortical areas engaged in different domains of behavior. Lesions of subcortical structures or projection/striatal fibers disrupt the contribution of subcortical nodes to behavior. Disconnection syndromes thus result from lesions of the cerebral cortex, subcortical structures, and WM tracts that link the nodes that make up the distributed circuits. The nature and the severity of the clinical manifestations of WM lesions are determined, in large part, by the location of the pathology: discrete neurological and neuropsychiatric symptoms result from focal WM lesions, whereas cognitive impairment across multiple domains—WM dementia—occurs in the setting of diffuse WM disease. We present a detailed review of the conditions affecting WM that produce these neurobehavioral syndromes, and consider the pathophysiology, clinical effects, and broad significance of the effects of aging and vascular compromise on cerebral WM, in an attempt to help further the understanding, diagnosis, and treatment of these disorders. PMID:18990132

  7. Heuristic modeling of macromolecule release from PLGA microspheres

    PubMed Central

    Szlęk, Jakub; Pacławski, Adam; Lau, Raymond; Jachowicz, Renata; Mendyk, Aleksander

    2013-01-01

    Dissolution of protein macromolecules from poly(lactic-co-glycolic acid) (PLGA) particles is a complex process and still not fully understood. As such, there are difficulties in obtaining a predictive model that could be of fundamental significance in design, development, and optimization for medical applications and toxicity evaluation of PLGA-based multiparticulate dosage form. In the present study, two models with comparable goodness of fit were proposed for the prediction of the macromolecule dissolution profile from PLGA micro- and nanoparticles. In both cases, heuristic techniques, such as artificial neural networks (ANNs), feature selection, and genetic programming were employed. Feature selection provided by fscaret package and sensitivity analysis performed by ANNs reduced the original input vector from a total of 300 input variables to 21, 17, 16, and eleven; to achieve a better insight into generalization error, two cut-off points for every method was proposed. The best ANNs model results were obtained by monotone multi-layer perceptron neural network (MON-MLP) networks with a root-mean-square error (RMSE) of 15.4, and the input vector consisted of eleven inputs. The complicated classical equation derived from a database consisting of 17 inputs was able to yield a better generalization error (RMSE) of 14.3. The equation was characterized by four parameters, thus feasible (applicable) to standard nonlinear regression techniques. Heuristic modeling led to the ANN model describing macromolecules release profiles from PLGA microspheres with good predictive efficiency. Moreover genetic programming technique resulted in classical equation with comparable predictability to the ANN model. PMID:24348037

  8. Heuristic modeling of macromolecule release from PLGA microspheres.

    PubMed

    Szlęk, Jakub; Pacławski, Adam; Lau, Raymond; Jachowicz, Renata; Mendyk, Aleksander

    2013-01-01

    Dissolution of protein macromolecules from poly(lactic-co-glycolic acid) (PLGA) particles is a complex process and still not fully understood. As such, there are difficulties in obtaining a predictive model that could be of fundamental significance in design, development, and optimization for medical applications and toxicity evaluation of PLGA-based multiparticulate dosage form. In the present study, two models with comparable goodness of fit were proposed for the prediction of the macromolecule dissolution profile from PLGA micro- and nanoparticles. In both cases, heuristic techniques, such as artificial neural networks (ANNs), feature selection, and genetic programming were employed. Feature selection provided by fscaret package and sensitivity analysis performed by ANNs reduced the original input vector from a total of 300 input variables to 21, 17, 16, and eleven; to achieve a better insight into generalization error, two cut-off points for every method was proposed. The best ANNs model results were obtained by monotone multi-layer perceptron neural network (MON-MLP) networks with a root-mean-square error (RMSE) of 15.4, and the input vector consisted of eleven inputs. The complicated classical equation derived from a database consisting of 17 inputs was able to yield a better generalization error (RMSE) of 14.3. The equation was characterized by four parameters, thus feasible (applicable) to standard nonlinear regression techniques. Heuristic modeling led to the ANN model describing macromolecules release profiles from PLGA microspheres with good predictive efficiency. Moreover genetic programming technique resulted in classical equation with comparable predictability to the ANN model.

  9. Effect of naloxone on regional cerebral blood flow during endotoxin shock in conscious rats

    SciTech Connect

    Law, W.R.; Ferguson, J.L. )

    1987-09-01

    Maintenance of cerebral blood flow (CBF) is vital during cardiovascular shock. Since opioids have been implicated in the pathophysiology of endotoxin shock and have been shown to alter cerebral perfusion patterns, the authors determined whether opioids were responsible for any of the changes in regional CBF observed during endotoxin shock and whether the use of naloxone might impair or aid in the maintenance of CBF. When blood flow (BF) is studied with radioactively-labeled microspheres in rats, the left ventricle of the heart is often cannulated via the right carotid artery. Questions have arisen concerning the potential adverse effects of this method on CBF in the hemisphere ipsilateral to the ligated artery. They measured right and left regional CBF by use of this route of cannulation. Twenty-four hours after cannulations were performed, flow measurements were made using radiolabeled microspheres in conscious unrestrained male Sprague-Dawley rats (300-400 g) before and 10, 30, and 60 min after challenging with 10 mg/kg Escherichia coli endotoxin (etx) or saline. Naloxone (2 mg/kg) or saline was given as a treatment 25 min post-etx. They found no significant differences between right and left cortical, midbrain, or cerebellar BF at any time in any treatment group. Therefore naloxone treatment of endotoxin shock may be beneficial in preventing decreases in regional CBF.

  10. Cytotoxic T cell vaccination with PLGA microspheres interferes with influenza A virus replication in the lung and suppresses the infectious disease.

    PubMed

    Herrmann, Valerie L; Hartmayer, Carmen; Planz, Oliver; Groettrup, Marcus

    2015-10-28

    Current influenza virus vaccines aim to elicit antibodies directed toward viral surface glycoproteins, which however are prone to antigenic drift. Cytotoxic T lymphocytes (CTLs) can exhibit heterosubtypic immunity against most influenza A viruses. In our study, we encapsulated the highly conserved, immunodominant, HLA-A*0201 restricted epitope from the influenza virus matrix protein M158-66 together with TLR ligands in biodegradable poly(d,l-lactide-co-glycolide) (PLGA) microspheres. Subcutaneous immunization of transgenic mice expressing chimeric HLA-A*0201 molecules with these microspheres induced a strong and sustained CTL response which sufficed to prevent replication of a recombinant vaccinia virus expressing the influenza A virus (IAV) matrix protein but not the replication of IAV in the lung. However, subcutaneous priming followed by intranasal boosting with M158-66 bearing PLGA microspheres was able to induce vigorous CTL responses both in the lung and spleen of mice which interfered with IAV replication, weight loss, and infection-related death. Taken together, vaccination with well-defined and highly conserved IAV-derived CTL epitopes encapsulated into clinically compatible PLGA microspheres contribute to the control of influenza A virus infections. The promptitude and broad reactivity of the CTL response may help to attenuate pandemic outbreaks of influenza viruses. PMID:26276509

  11. Cytotoxic T cell vaccination with PLGA microspheres interferes with influenza A virus replication in the lung and suppresses the infectious disease.

    PubMed

    Herrmann, Valerie L; Hartmayer, Carmen; Planz, Oliver; Groettrup, Marcus

    2015-10-28

    Current influenza virus vaccines aim to elicit antibodies directed toward viral surface glycoproteins, which however are prone to antigenic drift. Cytotoxic T lymphocytes (CTLs) can exhibit heterosubtypic immunity against most influenza A viruses. In our study, we encapsulated the highly conserved, immunodominant, HLA-A*0201 restricted epitope from the influenza virus matrix protein M158-66 together with TLR ligands in biodegradable poly(d,l-lactide-co-glycolide) (PLGA) microspheres. Subcutaneous immunization of transgenic mice expressing chimeric HLA-A*0201 molecules with these microspheres induced a strong and sustained CTL response which sufficed to prevent replication of a recombinant vaccinia virus expressing the influenza A virus (IAV) matrix protein but not the replication of IAV in the lung. However, subcutaneous priming followed by intranasal boosting with M158-66 bearing PLGA microspheres was able to induce vigorous CTL responses both in the lung and spleen of mice which interfered with IAV replication, weight loss, and infection-related death. Taken together, vaccination with well-defined and highly conserved IAV-derived CTL epitopes encapsulated into clinically compatible PLGA microspheres contribute to the control of influenza A virus infections. The promptitude and broad reactivity of the CTL response may help to attenuate pandemic outbreaks of influenza viruses.

  12. Coacervate-like microspheres from lysine-rich proteinoid

    NASA Technical Reports Server (NTRS)

    Rohlfing, D. L.

    1975-01-01

    Microspheres form isothermally from lysine-rich proteinoid when the ionic strength of the solution is increased with NaCl or other salts. Studies with different monovalent anions and with polymers of different amino acid composition indicate that charge neutralization and hydrophobic bonding contribute to microsphere formation. The particles also form in sea water, especially if heated or made slightly alkaline. The microspheres differ from those made from acidic proteinoid but resemble coacervate droplets in some ways (isothermal formation, limited stability, stabilization by quinone, uptake of dyes). Because the constituent lysine-rich proteinoid is of simulated prebiotic origin, the study is interpreted to add emphasis to and suggest an evolutionary continuity for coacervation phenomena.

  13. Biologically erodable microspheres as potential oral drug delivery systems

    NASA Astrophysics Data System (ADS)

    Mathiowitz, Edith; Jacob, Jules S.; Jong, Yong S.; Carino, Gerardo P.; Chickering, Donald E.; Chaturvedi, Pravin; Santos, Camilla A.; Vijayaraghavan, Kavita; Montgomery, Sean; Bassett, Michael; Morrell, Craig

    1997-03-01

    Biologically adhesive delivery systems offer important advantages1-5 over conventional drug delivery systems6. Here we show that engineered polymer microspheres made of biologically erodable polymers, which display strong adhesive interactions with gastrointestinal mucus and cellular linings, can traverse both the mucosal absorptive epithelium and the follicle-associated epithelium covering the lymphoid tissue of Peyer's patches. The polymers maintain contact with intestinal epithelium for extended periods of time and actually penetrate it, through and between cells. Thus, once loaded with compounds of pharmacological interest, the microspheres could be developed as delivery systems to transfer biologically active molecules to the circulation. We show that these microspheres increase the absorption of three model substances of widely different molecular size: dicumarol, insulin and plasmid DNA.

  14. Cell-laden Polymeric Microspheres for Biomedical Applications.

    PubMed

    Leong, Wenyan; Wang, Dong-An

    2015-11-01

    Microsphere technology serves as an efficient and effective platform for cell applications (in vitro cell culture and in vivo cell delivery) due to its mimicry of the 3D native environment, high surface area:volume ratio, and ability to isolate the entrapped cells from the environment. Properties of cell-laden microspheres are determined by the type of application and the cell. While high cell densities are preferable for large-scale therapeutic biomolecule production in vitro, an immunoprotective barrier is most important for allogeneic pancreatic islet transplantation into patients. Furthermore, the biological cells require a suitable microenvironment in terms of its physical and biochemical properties. Here, we discuss applications of cell-laden microspheres and their corresponding design parameters. PMID:26475118

  15. RF magnetron sputtering of thick platinum coatings on glass microspheres

    SciTech Connect

    Meyer, S.F.; Hsieh, E.J.; Burt, R.J.

    1980-05-28

    Thick platinum coatings on glass microspheres are needed for proposed Laser Fusion targets. The spherical nature of these substrates coupled with the small dimensions (approx. 100 ..mu..m OD) make it difficult to achieve a smooth and uniform coating. Coating problems encountered include a rough surface and porous microstructure from the oblique incidence and lack of temperature and bias control, clumping of the microspheres causing non-uniformities, and particle accumulation causing cone defects. Sputtering parameters significantly affecting the coatings include total pressure, DC substrate bias, and the addition of doping gases. Using an ultrasonic vibrating screened cage and RF magnetron Sputtergun, we have successfully batch coated microspheres with up to 6 ..mu..m of Pt, with a surface roughness of 200 nm, thickness non-concentricity of 300 nm, and density greater than 98% of bulk Pt.

  16. Electromigration of microspheres in ferroelectric smectic liquid crystals

    NASA Astrophysics Data System (ADS)

    Dierking, I.; Cass, P.; Syres, K.; Cresswell, R.; Morton, S.

    2007-08-01

    When an electric field is applied to microspheres which are dispersed in a ferroelectric smectic liquid crystal, particle translation along the smectic layer plane, i.e., in a direction nearly perpendicular to that of the director, can be observed. Under certain electric field conditions the translation is shown to be linear in time. We have determined the stability regime of linear particle displacement in the parameter space of amplitude and frequency for various applied wave forms. This regime enlarges for increasing electric field amplitude and frequency, with a threshold behavior observed for small parameters. The upper stability boundary is related to the reciprocal ferroelectric switching time. The microspheres translational velocity is independent of the applied electric field amplitude, but increases linearly with applied frequency. The microsphere velocity also increases with increasing temperature, which is indicative of the respective decrease in liquid crystal viscosity. Possible mechanisms of electric-field-induced particle motion are discussed.

  17. Cephradin-plaga microspheres for sustained delivery to cattle.

    PubMed

    Ustariz-Peyret, C; Coudane, J; Vert, M; Kaltsatos, V; Boisramé, B

    1999-01-01

    In the field of controlled drug delivery, most of the reported work is aimed at introducing new systems, or at providing basic information on the critical parameters which affect release profiles in vitro and occasionally in vivo. The situation is totally different when one wants to fulfil the specific requirements imposed by the marketing of a sustained release device to be used in humans or in animals eaten by human beings. The control of the release characteristics is then a difficult challenge. In this work, attempts were made to combine cephradin, a hydrophilic beta-lactam antibiotic, and bioresorbable polymeric matrices of a poly(alpha-hydroxy acid) in the form of microspheres with the aim of delivering the antibiotic to cattle at a dose rate of 4-5 mg/kg/day over a 3-4 days period after i.m. injection. PLAGA aliphatic polyesters were selected because they are already FDA approved as matrices. The solvent evaporation technique using PVA as the emulsion stabilizer was selected because it is efficient and can be extended to an industrial scale. Various experimental conditions were used in order to obtain the highest encapsulation yields compatible with the desired specifications. Decreasing the volume of the aqueous phase and adding a water-miscible organic solvent/non-solvent of cephradin failed. In contrast, microspheres containing up to 30% cephradin were prepared after addition of sodium chloride to the aqueous dispersing phase. The amount of entrapped drug was raised to 40% by decreasing the temperature and the pressure. Preliminary investigations using dogs showed that 20% cephradin microspheres prepared under these conditions extended the presence of cephradin in the blood circulation up to 48 h. Increasing the load led to higher blood concentrations but shorter sustained release. The fact that the microspheres were for cattle limited the volume of the injection and thus the amount of microspheres to be administered. The other limiting factors were

  18. Polysaccharide-based aerogel microspheres for oral drug delivery.

    PubMed

    García-González, C A; Jin, M; Gerth, J; Alvarez-Lorenzo, C; Smirnova, I

    2015-03-01

    Polysaccharide-based aerogels in the form of microspheres were investigated as carriers of poorly water soluble drugs for oral administration. These bio-based carriers may combine the biocompatibility of polysaccharides and the enhanced drug loading capacity of dry aerogels. Aerogel microspheres from starch, pectin and alginate were loaded with ketoprofen (anti-inflammatory drug) and benzoic acid (used in the management of urea cycle disorders) via supercritical CO2-assisted adsorption. Amount of drug loaded depended on the aerogel matrix structure and composition and reached values up to 1.0×10(-3) and 1.7×10(-3) g/m(2) for ketoprofen and benzoic acid in starch microspheres. After impregnation, drugs were in the amorphous state in the aerogel microspheres. Release behavior was evaluated in different pH media (pH 1.2 and 6.8). Controlled drug release from pectin and alginate aerogel microspheres fitted Gallagher-Corrigan release model (R(2)>0.99 in both cases), with different relative contribution of erosion and diffusion mechanisms depending on the matrix composition. Release from starch aerogel microspheres was driven by dissolution, fitting the first-order kinetics due to the rigid starch aerogel structure, and showed different release rate constant (k1) depending on the drug (0.075 and 0.160 min(-1) for ketoprofen and benzoic acid, respectively). Overall, the results point out the possibilities of tuning drug loading and release by carefully choosing the polysaccharide used to prepare the aerogels.

  19. Calcium phosphate-alginate microspheres as enzyme delivery matrices.

    PubMed

    Ribeiro, C C; Barrias, C C; Barbosa, M A

    2004-08-01

    The present study concerns the preparation and initial characterisation of novel calcium titanium phosphate-alginate (CTP-alginate) and hydroxyapatite-alginate (HAp-alginate) microspheres, which are intended to be used as enzyme delivery matrices and bone regeneration templates. Microspheres were prepared using different concentrations of polymer solution (1% and 3% w/v) and different ceramic-to-polymer solution ratios (0.1, 0.2 and 0.4 w/w). Ceramic powders were characterised using X-ray diffraction, laser granulometry, Brunauer, Emmel and Teller (BET) method for the determination of surface area, zeta potential and Fourier transform infrared spectroscopy (FT-IR). Alginate was characterised using high performance size exclusion chromatography. The methodology followed in this investigation enabled the preparation of homogeneous microspheres with a uniform size. Studies on the immobilisation and release of the therapeutic enzyme glucocerebrosidase, employed in the treatment of Gaucher disease, were also performed. The enzyme was incorporated into the ceramic-alginate matrix before gel formation in two different ways: pre-adsorbed onto the ceramic particles or dispersed in the polymeric matrix. The two strategies resulted in distinct release profiles. Slow release was obtained after adsorption of the enzyme to the ceramic powders, prior to preparation of the microspheres. An initial fast release was achieved when the enzyme and the ceramic particles were dispersed in the alginate solution before producing the microspheres. The latter profile is very similar to that of alginate microspheres. The different patterns of enzyme release increase the range of possible applications of the system investigated in this work.

  20. Preparation of anti-CD40 antibody modified magnetic PCL-PEG-PCL microspheres.

    PubMed

    Gao, Xiang; Kan, Bing; Gou, MaLing; Zhang, Juan; Guo, Gang; Huang, Ning; Zhao, Xia; Qian, ZhiYong

    2011-04-01

    Antibody modified magnetic polymeric microspheres have potential biomedical application. In this paper, anti-CD40 antibody modified magnetic poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCL-PEG-PCL, PCEC) microspheres were prepared. First, PCL-PEG-PCL triblock copolymer was synthesized by ring-opening polymerization, followed by reaction with succinic anhydride, creating carboxylated PCL-PEG-PCL copolymer. Then, magnetite nanoparticles were encapsulated into carboxylated PCL-PEG-PCL microspheres, forming magnetic PCL-PEG-PCL microspheres with carboxyl group on their surface. Catalyzed by EDC/NHS, the anti-CD40 antibody was linked to these magnetic PCL-PEG-PCL microspheres, thus forming anti-CD40 modified PCL-PEG-PCL microspheres. These anti-CD40 antibody modified magnetic PCL-PEG-PCL microspheres may have potential application in cell separation. PMID:21702366

  1. Fluoride Release from Hollow Silica Microsphere-Containing Dental Restorative Acrylate Resin.

    PubMed

    Ji, Yuqin; Gao, Jun; Yin, Hengbo; Wang, Aili; Jiang, Tingshun; Wu, Gang; Wu, Zhanao

    2015-05-01

    Hollow silica microspheres with mesoporous shells were prepared by the sacrificial template method. Hollow silica microsphere-containing acrylate resin-based dental restoration materials were prepared by using hollow silica microspheres as NaF reservoirs. Fluoride release performances from naked hollow silica microspheres, acrylate resin, and hollow silica microsphere-containing acrylate resin-based dental restorative materials in an artificial saliva were investigated. The results showed that hollow silica microsphere-containing acrylate resin-based dental restorative materials had higher cumulative fluoride release quantities and sustained fluoride release rates than traditional acrylate resin-based dental restorative materials. Fluoride release could be tuned by changing the mesoporous shell thickness of hollow silica microsphere.

  2. Preparation of monodisperse porous silica particles using poly(glycidyl methacrylate) microspheres as a template.

    PubMed

    Grama, S; Horák, D

    2015-01-01

    Monodisperse macroporous poly(glycidyl methacrylate) (PGMA) microspheres were used as a template for preparing porous silica particles. The starting polymer microspheres that were 9.3 microm in size were synthesized by multistep swelling polymerization using a modified Ugelstad technique. Subsequently, silica (SiO2) was deposited on the surface and inside the PGMA microspheres to produce poly(glycidyl methacrylate)-silica hybrid particles (PGMA-SiO2). Upon calcination of the PGMA-SiO2 microspheres, porous silica particles were formed. The morphology, particle size, polydispersity and inner structure of the silica microspheres were investigated by scanning and transmission electron microscopy. Thermogravimetric analysis and dynamic adsorption of nitrogen determined the amount of silica formed and its specific surface area. Compared with the starting PGMA microspheres, the size of the porous silica particles decreased by up to 30%. These porous silica microspheres are promising for chromatography and biomedical applications. PMID:26447591

  3. Preparation and structure of drug-carrying biodegradable microspheres designed for transarterial chemoembolization therapy.

    PubMed

    Wang, Yujing; Benzina, Abderazak; Molin, Daniel G M; Akker, Nynke van den; Gagliardi, Mick; Koole, Leo H

    2015-01-01

    Biodegradable poly(D,L-lactic acid) drug-eluting microspheres containing anti-tumor drugs, cisplatin, and sorafenib tosylate have been prepared by the emulsion solvent evaporation method with diameter between 200 and 400 μm. Scanning electron microscopy showed that cisplatin microspheres had smooth surfaces, while sorafenib tosylate microspheres and cisplatin + sorafenib tosylate microspheres were porous at the surface and the pits of the latter were larger than those of the former. Notably, cisplatin + sorafenib tosylate microspheres had a fast drug release rate compared with microspheres containing one drug alone. In vitro cytotoxicity experiments and classical matrigel endothelial tube assay certificated the maintaining bioactivity of cisplatin and sorafenib tosylate released from the microspheres, respectively. This work provides a useful approach for the fabrication of drug-eluting beads used in transarterial chemoembolization.

  4. Preparation of monodisperse porous silica particles using poly(glycidyl methacrylate) microspheres as a template.

    PubMed

    Grama, S; Horák, D

    2015-01-01

    Monodisperse macroporous poly(glycidyl methacrylate) (PGMA) microspheres were used as a template for preparing porous silica particles. The starting polymer microspheres that were 9.3 microm in size were synthesized by multistep swelling polymerization using a modified Ugelstad technique. Subsequently, silica (SiO2) was deposited on the surface and inside the PGMA microspheres to produce poly(glycidyl methacrylate)-silica hybrid particles (PGMA-SiO2). Upon calcination of the PGMA-SiO2 microspheres, porous silica particles were formed. The morphology, particle size, polydispersity and inner structure of the silica microspheres were investigated by scanning and transmission electron microscopy. Thermogravimetric analysis and dynamic adsorption of nitrogen determined the amount of silica formed and its specific surface area. Compared with the starting PGMA microspheres, the size of the porous silica particles decreased by up to 30%. These porous silica microspheres are promising for chromatography and biomedical applications.

  5. Natural mucoadhesive microspheres of Abelmoschus esculentus polysaccharide as a new carrier for nasal drug delivery.

    PubMed

    Sharma, Nitin; Kulkarni, Giriraj T; Sharma, Anjana; Bhatnagar, Aseem; Kumar, Neeraj

    2013-01-01

    This work describes the preparation and evaluation of mucoadhesive microspheres, using Abelmoschus esculentus polysaccharide as a novel carrier for safe and effective delivery of rizatriptan benzoate into nasal cavity. The polysaccharide was extracted from the fruit of A. esculentus and mucoadhesive microspheres were prepared by emulsification, followed by crosslinking using epichlorohydrin. Prepared microspheres were evaluated for size, morphology, swelling properties, mucoadhesive strength, encapsulation efficiency and drug release. Microspheres were found to release 50% of drug within 15 min and rest of the drug was released within 60 min. The drug release was found to decrease with increasing concentration of polysaccharide. To determine the retention time of the microspheres in the nasal cavity of rabbits, the microspheres were radiolabelled with (99m)Tc and subjected to gamma scintigraphy. The results showed a significant improvement in the nasal retention of the microspheres as compared to the aqueous solution of radiolabelled free-drug. PMID:23379506

  6. Modified composite microspheres of hydroxyapatite and poly(lactide-co-glycolide) as an injectable scaffold

    NASA Astrophysics Data System (ADS)

    Hu, Xixue; Shen, Hong; Yang, Fei; Liang, Xinjie; Wang, Shenguo; Wu, Decheng

    2014-02-01

    The compound of hydroxyapatite-poly(lactide-co-glycolide) (HA-PLGA) was prepared by ionic bond between HA and PLGA. HA-PLGA was more stable than the simple physical blend of hydroxyapatite and poly(lactide-co-glycolide) (HA/PLGA). The surface of HA-PLGA microsphere fabricated by an emulsion-solvent evaporation method was rougher than that of HA/PLGA microspheres. Moreover, surface HA content of HA-PLGA microspheres was more than that of HA/PLGA microspheres. In vitro mouse OCT-1 osteoblast-like cell culture results showed that the HA-PLGA microspheres clearly promoted osteoblast attachment, proliferation and alkaline phosphatase activity. It was considered that surface rich HA component and rough surface of HA-PLGA microsphere enhanced cell growth and differentiation. The good cell affinity of the HA-PLGA microspheres indicated that they could be used as an injectable scaffold for bone tissue engineering.

  7. Contribution of the vertebral artery to cerebral circulation in the rat snake Elaphe obsoleta

    NASA Technical Reports Server (NTRS)

    Zippel, K. C.; Lillywhite, H. B.; Mladinich, C. R.; Hargens, A. (Principal Investigator)

    1998-01-01

    Blood supplying the brain in vertebrates is carried primarily by the carotid vasculature. In most mammals, cerebral blood flow is supplemented by the vertebral arteries, which anastomose with the carotids at the base of the brain. In other tetrapods, cerebral blood is generally believed to be supplied exclusively by the carotid vasculature, and the vertebral arteries are usually described as disappearing into the dorsal musculature between the heart and head. There have been several reports of a vertebral artery connection with the cephalic vasculature in snakes. We measured regional blood flows using fluorescently labeled microspheres and demonstrated that the vertebral artery contributes a small but significant fraction of cerebral blood flow (approximately 13% of total) in the rat snake Elaphe obsoleta. Vascular casts of the anterior vessels revealed that the vertebral artery connection is indirect, through multiple anastomoses with the inferior spinal artery, which connects with the carotid vasculature near the base of the skull. Using digital subtraction angiography, fluoroscopy, and direct observations of flow in isolated vessels, we confirmed that blood in the inferior spinal artery flows craniad from a point anterior to the vertebral artery connections. Such collateral blood supply could potentially contribute to the maintenance of cerebral circulation during circumstances when craniad blood flow is compromised, e.g., during the gravitational stress of climbing.

  8. Assembly of microspheres with polymers by evaporating emulsion droplets

    NASA Astrophysics Data System (ADS)

    Lin, Keng-Hui; Lai, Liang-Jie; Chang, Chih-Chung; Chen, Hui

    2008-10-01

    We study the packing of colloidal microspheres mixed with polymers in oil-in-water emulsion droplets by evaporation. The addition of polymers produces non-unique configurations of final clusters when the number of particles N inside the droplet is larger than 4. The cluster configurations are classified into three categories based on symmetry. Stablized colloidal clusters of spherical packings are observed. Our observations on packing process suggest the mechanisms which cause different and nonunique structures. The osmotic pressure and the interparticle interaction due to polymers changes the force balance between microspheres and result in different structures.

  9. Use of molecular beams to support microspheres during plasma coating

    SciTech Connect

    Crane, J.K.; Smith, R.D.; Johnson, W.L.; Letts, S.A.; Korbel, G.R.; Krenick, R.M.

    1980-08-26

    Spherical laser fusion targets can be levitated on beams of Ar or other gas atoms. This is an especially useful and reliable technique for supporting microspheres during plasma coating or plasma etching. The reliability of this technique is principally the result of two things: the success of a special centering device which provides a lateral, stabilizing force on the levitated microspheres; and a gas handling system which is capable of controlling levitation gas flow in the microtorr liter/sec range. We have determined that the operational regime of this device is that of Knudsen's flow. This knowledge of the flow characteristics has been important in developing this device.

  10. Force detection with an optically levitated microsphere in vacuum

    NASA Astrophysics Data System (ADS)

    Ranjit, G.; Atherton, D.; Stutz, J.; Cunningham, M.; Karr, D.; Geraci, A. A.

    2014-05-01

    A microsphere levitated using purely optical forces in vacuum has a high quality factor and can be used as a micro-mechanical sensor for the precise measurements of small forces such as non-Newtonian gravity in the nanoscale regime and Casimir forces. In this talk, I will discuss the progress on our experiment towards the cooling of the center-of-mass motion of a dielectric microsphere trapped in an optical cavity. I will also discuss the calibration of the force sensitivity using known modulated electric fields. NSF grant PHY-1205994.

  11. Nanoscale compression of polymer microspheres by atomic force microscopy.

    PubMed

    Tan, Susheng; Sherman, Robert L; Ford, Warren T

    2004-08-17

    Atomic force microscopy (AFM) was employed to probe the mechanical properties of surface-charged polystyrene microspheres with 1-12 mol% of vinylbenzyl(trimethyl)ammonium chloride (VBTA) units. On the basis of Hertz's theory of contact mechanics, compressive moduli between 1 and 2 GPa were measured by the analysis of force-displacement curves captured on the particles via the force-volume technique. The deformation of the top of the polystyrene particles by the AFM tip was used to calculate the surface modulus. The compressive moduli are slightly less than the moduli of polystyrene bulk materials. The modulus of the polystyrene microspheres increases with an increase of the VBTA content.

  12. Facile fabrication of various zinc-nickel citrate microspheres and their transformation to ZnO-NiO hybrid microspheres with excellent lithium storage properties

    NASA Astrophysics Data System (ADS)

    Xie, Qingshui; Ma, Yating; Zeng, Deqian; Wang, Laisen; Yue, Guanghui; Peng, Dong-Liang

    2015-02-01

    Zinc-nickel citrate microspheres are prepared by a simple aging process of zinc citrate solid microspheres in nickel nitrate solution. As the concentration of nickel nitrate solution increases, the morphology of the produced zinc-nickel citrate evolves from solid, yolk-shell to hollow microspheres. The formation mechanism of different zinc-nickel citrate microspheres is discussed. After annealing treatment of the corresponding zinc-nickel citrate microspheres in air, three different ZnO-NiO hybrid architectures including solid, yolk-shell and hollow microspheres can be successfully fabricated. When applied as the anode materials for lithium ion batteries, ZnO-NiO hybrid yolk-shell microspheres demonstrate the best electrochemical properties than solid and hollow counterparts. After 200th cycles, ZnO-NiO hybrid yolk-shell microspheres deliver a high reversible capacity of 1176 mA h g-1. The unique yolk-shell configuration, the synergetic effect between ZnO and NiO and the catalytic effect of metal Ni generated by the reduction of NiO during discharging process are responsible for the excellent lithium storage properties of ZnO-NiO hybrid yolk-shell microspheres.

  13. Facile fabrication of various zinc-nickel citrate microspheres and their transformation to ZnO-NiO hybrid microspheres with excellent lithium storage properties

    PubMed Central

    Xie, Qingshui; Ma, Yating; Zeng, Deqian; Wang, Laisen; Yue, Guanghui; Peng, Dong-Liang

    2015-01-01

    Zinc-nickel citrate microspheres are prepared by a simple aging process of zinc citrate solid microspheres in nickel nitrate solution. As the concentration of nickel nitrate solution increases, the morphology of the produced zinc-nickel citrate evolves from solid, yolk-shell to hollow microspheres. The formation mechanism of different zinc-nickel citrate microspheres is discussed. After annealing treatment of the corresponding zinc-nickel citrate microspheres in air, three different ZnO-NiO hybrid architectures including solid, yolk-shell and hollow microspheres can be successfully fabricated. When applied as the anode materials for lithium ion batteries, ZnO-NiO hybrid yolk-shell microspheres demonstrate the best electrochemical properties than solid and hollow counterparts. After 200th cycles, ZnO-NiO hybrid yolk-shell microspheres deliver a high reversible capacity of 1176 mA h g−1. The unique yolk-shell configuration, the synergetic effect between ZnO and NiO and the catalytic effect of metal Ni generated by the reduction of NiO during discharging process are responsible for the excellent lithium storage properties of ZnO-NiO hybrid yolk-shell microspheres. PMID:25684436

  14. Cerebral and Tissue Oximetry

    PubMed Central

    Steppan, Jochen; Hogue, Charles W.

    2014-01-01

    The use of near-infrared spectroscopy (NIRS) has been increasingly adopted in cardiac surgery to measure regional cerebral oxygen saturation. This method takes advantage of the fact that light in the near-infrared spectrum penetrates tissue, including bone and muscle. Sensors are placed at fixed distances from a light emitter, and algorithms subtract superficial light absorption from deep absorption to provide an index of tissue oxygenation. Although the popularity of NIRS monitoring is growing, definitive data that prove outcome benefits with its use remain sparse. Therefore, widespread, routine use of NIRS as a standard-of-care monitor cannot be recommended at present. Recent investigations have focused on the use of NIRS in subgroups that may benefit from NIRS monitoring, such as pediatric patients. Furthermore, a novel application of processed NIRS information for monitoring cerebral autoregulation and tissue oxygenation (e.g., kidneys and the gut) is promising. PMID:25480772

  15. Music and cerebral hemodynamics.

    PubMed

    Marinoni, M; Grassi, E; Latorraca, S; Caruso, A; Sorbi, S

    2000-09-01

    Previous studies performed by positron emission tomography and Transcranial Doppler (TCD) found a different cerebral activation during musical stimuli in musicians compared to non-musicians. The aim of our study is to evaluate by means of TCD, possible different pattern of cerebral activation during the performance of different musical tasks in musicians, non-musicians and lyrical singers. Our findings show a left hemispheric activation in musicians and a right one in non-musicians. Preliminary data on lyrical singers' activation patterns need further confirmation with a larger population. These data could be related to a different approach to music listening in musicians (analytical) and non-musicians who are supposed to have an emotional approach to music. PMID:10942664

  16. Cerebral localization in antiquity.

    PubMed

    Rose, F Clifford

    2009-07-01

    Fragments of neurology can be found in the oldest medical writings in antiquity. Recognizable cerebral localization is seen in Egyptian medical papyri. Most notably, the Edwin Smith papyrus describes hemiplegia after a head injury. Similar echoes can be seen in Homer, the Bible, and the pre-Hippocratic writer Alcmaeon of Croton. While Biblical writers thought that the heart was the seat of the soul, Hippocratic writers located it in the head. Alexandrian anatomists described the nerves, and Galen developed the ventricular theory of cognition whereby mental functions are classified and localized in one of the cerebral ventricles. Medieval scholars, including the early Church Fathers, modified Galenic ventricular theory so as to make it a dynamic model of cognition. Physicians in antiquity subdivided the brain into separate areas and attributed to them different functions, a phenomenon that connects them with modern neurologists. PMID:20183203

  17. What You Should Know about Cerebral Aneurysms

    MedlinePlus

    ... About Stroke What You Should Know About Cerebral Aneurysms Updated:Jun 13,2014 About Cerebral Aneurysms Diagnosis ... to view an animation What is a cerebral aneurysm? An aneurysm is a weak area in a ...

  18. Carbon dioxide induced changes in cerebral blood flow and flow velocity: role of cerebrovascular resistance and effective cerebral perfusion pressure

    PubMed Central

    Grüne, Frank; Kazmaier, Stephan; Stolker, Robert J; Visser, Gerhard H; Weyland, Andreas

    2015-01-01

    In addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO2-induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure–flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean VMCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39% despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r=0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP. PMID:25873428

  19. Molecular pathophysiology of cerebral edema.

    PubMed

    Stokum, Jesse A; Gerzanich, Volodymyr; Simard, J Marc

    2016-03-01

    Advancements in molecular biology have led to a greater understanding of the individual proteins responsible for generating cerebral edema. In large part, the study of cerebral edema is the study of maladaptive ion transport. Following acute CNS injury, cells of the neurovascular unit, particularly brain endothelial cells and astrocytes, undergo a program of pre- and post-transcriptional changes in the activity of ion channels and transporters. These changes can result in maladaptive ion transport and the generation of abnormal osmotic forces that, ultimately, manifest as cerebral edema. This review discusses past models and current knowledge regarding the molecular and cellular pathophysiology of cerebral edema. PMID:26661240

  20. Molecular pathophysiology of cerebral edema

    PubMed Central

    Gerzanich, Volodymyr; Simard, J Marc

    2015-01-01

    Advancements in molecular biology have led to a greater understanding of the individual proteins responsible for generating cerebral edema. In large part, the study of cerebral edema is the study of maladaptive ion transport. Following acute CNS injury, cells of the neurovascular unit, particularly brain endothelial cells and astrocytes, undergo a program of pre- and post-transcriptional changes in the activity of ion channels and transporters. These changes can result in maladaptive ion transport and the generation of abnormal osmotic forces that, ultimately, manifest as cerebral edema. This review discusses past models and current knowledge regarding the molecular and cellular pathophysiology of cerebral edema. PMID:26661240

  1. Cerebral organoids in a dish: progress and prospects.

    PubMed

    Bershteyn, Marina; Kriegstein, Arnold R

    2013-09-26

    A three-dimensional culture of cortical tissues derived from pluripotent stem cells offers an opportunity to model human brain development and disorders. In a recent issue of Nature, Lancaster et al. describe a new method for generating cerebral organoids in a dish and use it to model microcephaly. PMID:24074857

  2. Electrophoretic cell separation using microspheres. [purification of lymphocytes

    NASA Technical Reports Server (NTRS)

    Smolka, A.; Sachs, G.

    1980-01-01

    Methods of cell separation based on the electrokinetic properties of the cell membrane offer a degree of discrimination among cell populations which is not available with methods based on cell size or density alone. Studies aimed at extending red cell separations using microspheres to purification of lymphocytes.

  3. Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Feng, Zhenliang; Wei, Wenrui; Wang, Litong; Hong, Ruoyu

    2015-12-01

    Hollow titania microspheres (HTS) were fabricated via a sol-gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (-NH2) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO2 microspheres. Then the TiO2 particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2 μm in diameter) featured a high specific surface area (84.37 m2/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88 min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

  4. Coaxial electrohydrodynamic atomization process for production of polymeric composite microspheres

    PubMed Central

    Xu, Qingxing; Qin, Hao; Yin, Zhenyuan; Hua, Jinsong; Pack, Daniel W.; Wang, Chi-Hwa

    2013-01-01

    Polymeric composite microspheres consisting of a poly(D,L-lactic-co-glycolic acid) (PLGA) core surrounded by a poly(D,L-lactic acid) (PDLLA) shell layer were successfully fabricated by coaxial electrohydrodynamic atomization (CEHDA) process. Process conditions, including nozzle voltage and polymer solution flow rates, as well as solution parameters, such as polymer concentrations, were investigated to ensure the formation of composite microspheres with a doxorubicin-loaded PLGA core surrounded by a relatively drug-free PDLLA shell layer. Various microsphere formulations were fabricated and characterized in terms of their drug distribution, encapsulation efficiency and in vitro release. Numerical simulation of CEHDA process was performed based on a computational fluid dynamics (CFD) model in Fluent by employing the process conditions and fluid properties used in the experiments. The simulation results were compared with the experimental work to illustrate the capability of the CFD model to predict the production of consistent compound droplets, and hence, the expected core-shell structured microspheres. PMID:24347672

  5. Remediation of coal mining wastewaters using chitosan microspheres.

    PubMed

    Geremias, R; Pedrosa, R C; Benassi, J C; Fávere, V T; Stolberg, J; Menezes, C T B; Laranjeira, M C M

    2003-12-01

    This study aimed to evaluate the potential use of chitosan and chitosan/poly(vinylalcohol) microspheres incorporating with tetrasulphonated copper (II) phthalocyanine (CTS/PVA/TCP) in the remediation of coal mining wastewaters. The process was monitored by toxicity tests both before and after adsorption treatments with chitosan and microspheres. Physicochemical parameters, including pH and trace-metal concentration, as well as bioindicators of water pollution were used to that end. Wastewater samples colleted from drainage of underground coal mines, decantation pools, and contaminated rivers were scrutinized. Acute toxicity tests were performed using the Brine Shrimp Test (BST) in order to evaluate the remediation efficiency of different treatments. The results showed that the pH of treated wastewater samples were improved to values close to neutrality. Chitosan treatments were also effective in removing trace-metals. Pre-treatment with chitosan followed by microsphere treatment (CTS/PVA/TCP) was more effective in decreasing toxicity than the treatment using only chitosan. This was probably due to the elimination of pollutants other than trace-metals. Thus, the use of chitosan and microspheres is an adequate alternative towards remediation of water pollution from coal mining. PMID:14977147

  6. Statistical design of position-encoded microsphere arrays.

    PubMed

    Sarder, Pinaki; Nehorai, Arye

    2011-03-01

    We propose a microsphere array device with microspheres having controllable positions for error-free target identification. We conduct a statistical design analysis to select the optimal distance between the microspheres as well as the optimal temperature. Our design simplifies the imaging and ensures a desired statistical performance for a given sensor cost. Specifically, we compute the posterior Cramér-Rao bound on the errors in estimating the unknown target concentrations. We use this performance bound to compute the optimal design variables. We discuss both uniform and sparse concentration levels of targets, and replace the unknown imaging parameters with their maximum likelihood estimates. We illustrate our design concept using numerical examples. The proposed microarray has high sensitivity, efficient packing, and guaranteed imaging performance. It simplifies the imaging analysis significantly by identifying targets based on the known positions of the microspheres. Potential applications include molecular recognition, specificity of targeting molecules, protein-protein dimerization, high throughput screening assays for enzyme inhibitors, drug discovery, and gene sequencing.

  7. [Study on preparation process of artesunate polylactic acid microspheres].

    PubMed

    Pan, Xu-Wang; Wang, Wei; Fang, Hong-Ying; Wang, Fu-Gen; Cai, Zhao-Bin

    2013-12-01

    This study aims to investigate the preparation process and in vitro release behavior of artesunate polylactic acid microspheres, in order to prepare an artesunate polylactic acid (PLA) administration method suitable for hepatic arterial embolization. With PLA as the material and polyvinyl alcohol (PVA) as the emulsifier, O/W emulsion/solvent evaporation method was adopted to prepare artesunate polylactic acid microspheres, and optimize the preparation process. With drug loading capacity, encapsulation efficiency and particle size as indexes, a single factor analysis was made on PLA concentration, PVA concentration, drug loading ratio and stirring velocity. Through an orthogonal experiment, the optimal processing conditions were determined as follows: PLA concentration was 9. 0% , PVA concentration was 0. 9% , drug loading ratio was 1:2 and stirring velocity was 1 000 r x min(-1). According to the verification of the optimal process, microsphere size, drug loading and entrapment rate of artesunate polylactic acid microspheres were (101.7 +/- 0.37) microm, (30.8 +/- 0.84)%, (53.6 +/- 0.62)%, respectively. The results showed that the optimal process was so reasonable and stable that it could lay foundation for further studies.

  8. Facile fabrication and supercapacitive properties of mesoporous zinc cobaltite microspheres

    NASA Astrophysics Data System (ADS)

    Wang, Qinghong; Du, Jialu; Zhu, Yuxuan; Yang, Jiaqin; Chen, Juan; Wang, Chao; Li, Liang; Jiao, Lifang

    2015-06-01

    Mesoporous zinc cobaltite (ZnCo2O4) microspheres have been successfully prepared by a facile solvothermal method followed by an annealing process. The as-prepared ZnCo2O4 displays uniform sphere-like morphology composed of interconnected ZnCo2O4 nanoparticles. The Brunauer-Emmett-Teller (BET) surface area of mesoporous ZnCo2O4 microspheres is about 51.4 m2 g-1 with dominant pore diameter of 7.5 nm. The novel ZnCo2O4 material exhibits high specific capacitance of 953.2 F g-1 and 768.5 F g-1 at discharge current densities of 4 A g-1 and 30 A g-1, respectively. The energy density can be estimated to be 26.68 Wh kg-1 at a power density of 8 kW kg-1. The specific capacitance retention is 97.8% after 3000 cycles, suggesting its excellent cycling stability. The superior electrochemical performance is mainly attributed to the uniformity of the surface structure and the porosity of the microspheres, which benefit electrons and ions transportation, provide large electrode-electrolyte contact area, and meanwhile reduce volume change during the charge-discharge process. This method of constructing porous microspheres is very effective, yet simple, and it could be applied in other high-performance metal oxide electrode materials for electrochemical capacitors, as well as in Li-ion batteries.

  9. Preparation and evaluation of chitosan microspheres containing nicorandil

    PubMed Central

    Patel, Keyur S; Patel, Mandev B

    2014-01-01

    Objectives: The objective of present study was to develop chitosan-based sustained release nicorandil microspheres to reduce the dosing frequency. Materials and Methods: The nicorandil-loaded chitosan microspheres were formulated by emulsion crosslinking method. A 32 factorial design was employed to study the influence of drug: Polymer ratio and volume of glutaraldehyde (GA) on percentage entrapment efficiency, particle size, and % drug release at 8 h. Results: The entrapment efficiency was found to be 41.67 ± 1.43-77.33 ± 1.97% and particle size range 65.67 ± 2.08-146.67 ± 2.18 μm. The batch CH5 showed 79.11 ± 2.23 and 96.21 ± 2.41% drug release at 8 and 12 h, respectively. Conclusions: Drug: Polymer ratio and volume of GA had significant effect on % entrapment efficiency, particle size, and % drug release. From the scanning electron microscopy (SEM) study observed that microspheres were spherical and fairly smooth surface. Fickian diffusion was the mode of drug release from nicorandil-loaded chitosan microspheres formulations. PMID:24678460

  10. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres.

    PubMed

    Cao, Feng; Li, Dongxu

    2010-03-01

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe(3+), which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 degrees C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  11. Hydrogel microspheres from biodegradable polymers as drug delivery systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of hydrogel microspheres were prepared from pectin, a hydrophilic biopolymer, and zein, a hydrophobic biopolymer, at varying weight ratios. The hydrogel formulation was conducted in the presence of calcium or other divalent metal ions at room temperature under mild conditions. Studies of ...

  12. Process for fabricating doped zinc oxide microsphere gel

    DOEpatents

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1991-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  13. Process for fabricating doped zinc oxide microsphere gel

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1991-11-05

    Disclosed are a new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  14. Coaxial electrohydrodynamic atomization process for production of polymeric composite microspheres.

    PubMed

    Xu, Qingxing; Qin, Hao; Yin, Zhenyuan; Hua, Jinsong; Pack, Daniel W; Wang, Chi-Hwa

    2013-12-18

    Polymeric composite microspheres consisting of a poly(D,L-lactic-co-glycolic acid) (PLGA) core surrounded by a poly(D,L-lactic acid) (PDLLA) shell layer were successfully fabricated by coaxial electrohydrodynamic atomization (CEHDA) process. Process conditions, including nozzle voltage and polymer solution flow rates, as well as solution parameters, such as polymer concentrations, were investigated to ensure the formation of composite microspheres with a doxorubicin-loaded PLGA core surrounded by a relatively drug-free PDLLA shell layer. Various microsphere formulations were fabricated and characterized in terms of their drug distribution, encapsulation efficiency and in vitro release. Numerical simulation of CEHDA process was performed based on a computational fluid dynamics (CFD) model in Fluent by employing the process conditions and fluid properties used in the experiments. The simulation results were compared with the experimental work to illustrate the capability of the CFD model to predict the production of consistent compound droplets, and hence, the expected core-shell structured microspheres.

  15. Microsphere embolization of nerve capillaries and fiber degeneration.

    PubMed Central

    Nukada, H.; Dyck, P. J.

    1984-01-01

    Polystyrene microspheres, the size chosen to plug capillaries and precapillaries, were injected into the arterial supply of rat sciatic nerves. They produced widespread segmental occlusion of capillaries in lower limb nerves. The clinical and pathologic effect was dose-related. One million microspheres produced selective capillary occlusion but no nerve fiber degeneration; approximately 6 million microspheres also produced selective capillary occlusion and associated foot and leg weakness, sensory loss, and fiber degeneration, beginning in a central core of the distal sciatic nerve; 30 million microspheres caused both capillary and arterial occlusion and a greater neuropathologic deficit. From these observations it is inferred that 1) occlusion of isolated precapillaries and capillaries does not produce ischemic fiber degeneration; 2) occlusion of many microvessels results in central fascicular fiber degeneration, indicating that these cores are watershed regions of poor perfusion; and 3) stereotyped pathologic alterations of nerve fibers and Schwann cells are related to dose, anatomic site, and time elapsed since injection. Images Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 PMID:6326580

  16. Chitosan-Montmorillonite microspheres: A sustainable fertilizer delivery system.

    PubMed

    dos Santos, Bruna Rodrigues; Bacalhau, Fabiana Britti; Pereira, Tamires dos Santos; Souza, Claudinei Fonseca; Faez, Roselena

    2015-08-20

    Controlled release fertilizers are efficient tools that increase the sustainability of agricultural practices. However, the biodegradability of the matrices and the determination of the release into soil still require some investigation. This paper describes the preparation of potassium-containing microspheres based on chitosan and montmorillonite clay and the in situ soil release. The chitosan-montmorillonite microspheres were prepared using a coagulation method and different proportions of montmorillonite. The structural, thermal and morphological properties as well the water swelling and fertilizer sorption capacity were evaluated. The best formulations were applied in soil, and the fertilizer release was monitored using time-domain reflectometry (TDR). Montmorillonite clay provides better sorption properties than the chitosan microspheres because of the rough and porous surface. Due to these properties, high levels of fertilizer were sorbed onto the material. ChMMT33-containing potassium shows two specific periods of fertilizer release: the first one lasted approximately three days and was assigned to the external fertilizer on the microspheres. The second was assigned to the internal fertilizer. TDR is an important and fast tool and was used to determine the fertilizer release and the ion movement in the soil. PMID:25965492

  17. Development of a roundness measuring system for microspheres

    NASA Astrophysics Data System (ADS)

    Fan, Kuang-Chao; Wang, Na; Wang, Zhi-Wei; Zhang, Hui

    2014-06-01

    In the field of micro/nano technology, microspheres are often used as the tip-ball of a measuring stylus, such as in micro/nano coordinate measuring machines (CMMs). Conventional tactile probes adopt ruby or steel balls with diameters in the range of several millimeters to 0.3 mm. For a micro-CMM, the required probing ball is as small as possible in order to be inserted into a small groove for side wall measurement. The exact diameter of the tip-ball has to be calibrated for radius compensation and its roundness error has to be qualified. A roundness measuring system for microspheres is developed in this study. Two small Michelson interferometers are designed for direct measurement of microsphere diameter from both sides, being a two-point method. By rotating the measured sphere and reading the displacement shifts of the two interferometers, the run-out of the sphere can be eliminated. The resolution of the developed system can reach 1 nm and the accuracy can reach 10 nm. Two microspheres are tested with good repeatability. This system can also be used for macrosphere measurement.

  18. Investigation of acetylated chitosan microspheres as potential chemoembolic agents.

    PubMed

    Zhou, Xuan; Kong, Ming; Cheng, Xiaojie; Li, Jingjing; Li, Jing; Chen, Xiguang

    2014-11-01

    The aim was to investigate the potential of chitosan microspheres (CMs) with different acetylation using as a chemoembolic agent. Chitosan microspheres (CMs) were prepared via water-in-oil (W/O) emulsification cross-linking method, and acetylated chitosan microspheres (ACMs) were obtained by acetylation of CMs. Next, we characterized the morphology, size, composition and degrees of deacetylation using scanning electron microscopy (TEM), dynamic laser light scattering (DLS), and Fourier transform infrared spectrometer (FTIR). All microspheres had smooth surfaces and good mechanical flexibility, and all could pass through a 5F catheter. The swelling rate (SR) of CMs decreased significantly with the increase of pH (4.0-10.0) but ACMs did not change under the same conditions. Protein absorption assays suggested that albumin was more greatly adsorbed on CMs than on ACMs. Furthermore, CMs caused more blood clots than ACMs. ACMs caused hemolysis less than CMs (<5% of the time). Data indicated that ACMs had more hemocompatibility. Cytotoxicity tests indicated that ACMs initially had less cell attached proliferation but increased with incubation. In contrast, the relative growth rate of mouse embryo fibroblasts (MEFs) on CMs decreased gradually. The results suggested that ACMs could stimulate the growth of MEFs, and CMs were not cytotoxic to MEFs. Thus, ACMs were more biocompatible with greater potential to be used as chemoembolic material.

  19. Acrylic microspheres-based optosensor for visual detection of nitrite.

    PubMed

    Noor, Nur Syarmim Mohamed; Tan, Ling Ling; Heng, Lee Yook; Chong, Kwok Feng; Tajuddin, Saiful Nizam

    2016-09-15

    A new optosensor for visual quantitation of nitrite (NO2(-)) ion has been fabricated by physically immobilizing Safranine O (SO) reagent onto a self-adhesive poly(n-butyl acrylate) [poly(nBA)] microspheres matrix, which was synthesized via facile microemulsion UV lithography technique. Evaluation and optimization of the optical NO2(-) ion sensor was performed with a fiber optic reflectance spectrophotometer. Scanning electron micrograph showed well-shaped and smooth spherical morphology of the poly(nBA) microspheres with a narrow particles size distribution from 0.6 μm up to 1.8 μm. The uniform size distribution of the acrylic microspheres promoted homogeneity of the immobilized SO reagent molecules on the microspheres' surfaces, thereby enhanced the sensing response reproducibility (<5% RSD) with a linear range obtained from 10 to 100 ppm NO2(-) ion. The micro-sized acrylic immobilization matrix demonstrated no significant barrier for diffusion of reactant and product, and served as a good solid state ion transport medium for reflectometric nitrite determination in food samples. PMID:27080889

  20. Porous metal oxide microspheres from ion exchange resin

    NASA Astrophysics Data System (ADS)

    Picart, S.; Parant, P.; Caisso, M.; Remy, E.; Mokhtari, H.; Jobelin, I.; Bayle, J. P.; Martin, C. L.; Blanchart, P.; Ayral, A.; Delahaye, T.

    2015-07-01

    This study is devoted to the synthesis and the characterization of porous metal oxide microsphere from metal loaded ion exchange resin. Their application concerns the fabrication of uranium-americium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Those mixed oxide ceramics are one of the materials envisaged for americium transmutation in sodium fast neutron reactors. The advantage of such microsphere precursor compared to classical oxide powder is the diminution of the risk of fine dissemination which can be critical for the handling of highly radioactive powders such as americium based oxides and the improvement of flowability for the filling of compaction chamber. Those millimetric oxide microspheres incorporating uranium and americium were synthesized and characterizations showed a very porous microstructure very brittle in nature which occurred to be adapted to shaping by compaction. Studies allowed to determine an optimal heat treatment with calcination temperature comprised between 700-800 °C and temperature rate lower than 2 °C/min. Oxide Precursors were die-pressed into pellets and then sintered under air to form regular ceramic pellets of 95% of theoretical density (TD) and of homogeneous microstructure. This study validated thus the scientific feasibility of the CRMP process to prepare bearing americium target in a powder free manner.

  1. Chitosan-Montmorillonite microspheres: A sustainable fertilizer delivery system.

    PubMed

    dos Santos, Bruna Rodrigues; Bacalhau, Fabiana Britti; Pereira, Tamires dos Santos; Souza, Claudinei Fonseca; Faez, Roselena

    2015-08-20

    Controlled release fertilizers are efficient tools that increase the sustainability of agricultural practices. However, the biodegradability of the matrices and the determination of the release into soil still require some investigation. This paper describes the preparation of potassium-containing microspheres based on chitosan and montmorillonite clay and the in situ soil release. The chitosan-montmorillonite microspheres were prepared using a coagulation method and different proportions of montmorillonite. The structural, thermal and morphological properties as well the water swelling and fertilizer sorption capacity were evaluated. The best formulations were applied in soil, and the fertilizer release was monitored using time-domain reflectometry (TDR). Montmorillonite clay provides better sorption properties than the chitosan microspheres because of the rough and porous surface. Due to these properties, high levels of fertilizer were sorbed onto the material. ChMMT33-containing potassium shows two specific periods of fertilizer release: the first one lasted approximately three days and was assigned to the external fertilizer on the microspheres. The second was assigned to the internal fertilizer. TDR is an important and fast tool and was used to determine the fertilizer release and the ion movement in the soil.

  2. Preparation of petaloid microspheres of basic magnesium carbonate.

    PubMed

    Ohkubo, Takahiro; Suzuki, Sei; Mitsuhashi, Kohei; Ogura, Taku; Iwanaga, Shinichi; Sakai, Hideki; Koishi, Masumi; Abe, Masahiko

    2007-05-22

    The synthesis of basic magnesium carbonate was examined under ultrasonic irradiation and was performed by the soda ash method using magnesium sulfate and sodium carbonate as starting materials. The particulate product was evaluated using SEM observations. Ultrasonic irradiation in the preparation of basic magnesium carbonate was found to give fine petaloid microspheres of about 3 mum in primary particle size. PMID:17458985

  3. A microfluidic approach to assembling ordered microsphere arrays

    NASA Astrophysics Data System (ADS)

    Xu, W.; Sur, K.; Zeng, H.; Feinerman, A.; Kelso, D.; Ketterson, J. B.

    2008-07-01

    Hydrodynamic flow through an array of channels has been utilized to assemble microspheres on a flat surface. The channels, about 6 µm in lateral size, were etched through a 60 µm thick silicon wafer using deep reactive ion etching (DRIE). Droplets containing 6-8 µm fluorescent polystyrene microspheres were placed on the top side of the horizontally-oriented silicon wafer, while the bottom side was connected to a syringe that draws the fluid through the channels. In this way the microspheres are guided and secured at the inlets of the channels, and remain in place when the suction ceases. This technique, which combines favorable features such as high throughput, high resolution rate and reusability, can be a powerful platform for a new generation of protein microarrays. Antigens can be bound to the microspheres as 'targets', which can then be exposed to different fluorescence-tagged antibodies so that their binding can be confirmed. This system can also be used to study the functional roles of gene fragments and their relations to human diseases. The high throughput feature will make it possible to screen a large number of DNA fragments and identify the genetic basis of various diseases effectively.

  4. Method for forming microspheres for encapsulation of nuclear waste

    DOEpatents

    Angelini, Peter; Caputo, Anthony J.; Hutchens, Richard E.; Lackey, Walter J.; Stinton, David P.

    1984-01-01

    Microspheres for nuclear waste storage are formed by gelling droplets containing the waste in a gelation fluid, transferring the gelled droplets to a furnace without the washing step previously used, and heating the unwashed gelled droplets in the furnace under temperature or humidity conditions that result in a substantially linear rate of removal of volatile components therefrom.

  5. BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

    SciTech Connect

    farquar, G; Leif, R

    2008-09-12

    Biocompatible polymers with hydrolyzable chemical bonds are being used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres are being produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. The advantages and disadvantages of each method will be presented and discussed in greater detail along with fluorescent and charge properties of the aerosols. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

  6. Adenylyl cyclase activation underlies intracellular cyclic AMP accumulation, cyclic AMP transport, and extracellular adenosine accumulation evoked by beta-adrenergic receptor stimulation in mixed cultures of neurons and astrocytes derived from rat cerebral cortex.

    PubMed

    Rosenberg, P A; Li, Y

    1995-09-18

    We have previously shown that stimulation of cortical cultures containing both neurons and astrocytes with the beta-adrenergic agonist isoproterenol (ISO) results in transport of cAMP from astrocytes followed by extracellular hydrolysis to adenosine [Rosenberg et al. J. Neurosci. 14 (1994) 2953-2965]. In this study we found that the endogenous catecholamines epinephrine (EPI) and norepinephrine (NE), but not dopamine, serotonin, or histamine, all at 10 microM, significantly stimulated intracellular cAMP accumulation, cAMP transport, and extracellular adenosine accumulation in cortical cultures. Detailed dose-response experiments were performed for NE and EPI, as well as ISO. For each catecholamine, the potencies in evoking intracellular cAMP accumulation, cAMP transport, and extracellular adenosine accumulation were similar. These data provide additional evidence that a single common mechanism, namely beta-adrenergic mediated activation of adenylyl cyclase, underlies intracellular cAMP accumulation, cAMP transport, and extracellular adenosine accumulation. It appears that regulation of extracellular adenosine levels via cAMP transport and extracellular hydrolysis to adenosine may be a final common pathway of neuromodulation in cerebral cortex for catecholamines, and, indeed, any substance whose receptors are coupled to adenylyl cyclase.

  7. Enhanced autonomic shutdown of Li-ion batteries by polydopamine coated polyethylene microspheres

    NASA Astrophysics Data System (ADS)

    Baginska, Marta; Blaiszik, Benjamin J.; Rajh, Tijana; Sottos, Nancy R.; White, Scott R.

    2014-12-01

    Thermally triggered autonomic shutdown of a Lithium-ion (Li-ion) battery is demonstrated using polydopamine (PDA)-coated polyethylene microspheres applied onto a battery anode. The microspheres are dispersed in a buffered 10 mM dopamine salt solution and the pH is raised to initiate the polymerization and coat the microspheres. Coated microspheres are then mixed with an aqueous binder, applied onto a battery anode surface, dried, and incorporated into Li-ion coin cells. FTIR and Raman spectroscopy are used to verify the presence of the polydopamine on the surface of the microspheres. Scanning electron microscopy is used to examine microsphere surface morphology and resulting anode coating quality. Charge and discharge capacity, as well as impedance, are measured for Li-ion coin cells as a function of microsphere content. Autonomous shutdown is achieved by applying 1.7 mg cm-2 of PDA-coated microspheres to the electrode. The PDA coating significantly reduces the mass of microspheres for effective shutdown compared to our prior work with uncoated microspheres.

  8. Evaluation of the Intestinal Colonizing Potential and Immunomodulating Capacity of Lactobacilli Microspheres.

    PubMed

    Cotta, Karyn I; Addo, Richard T; D'Souza, Martin J

    2016-05-01

    Lactobacilli species get degraded by acidic conditions in the stomach. Thus, the objective of this study was to (1) formulate and characterize gastro-resistant Lactobacilli microspheres and (2) evaluate the ability of Lactobacilli microspheres to colonize the intestine and their capacity to have an immunomodulating effect in vivo. The product yield and the encapsulation efficiency were 45% and 100%, respectively. The average microsphere particle size was 5 μm. Lactobacilli microspheres were most stable at 4°C and showed a better suspendibility in distilled water. Without encapsulation, the viability of bacteria decreased within 30 min. In the case of Lactobacilli microspheres, no Lactobacilli were released in the first 3 h, and highest release was observed at 4 h, thus, suggesting the significance of encapsulation of Lactobacilli. Lactobacilli microspheres maintained intestinal colonization only during the dosing period, and the serum IgG, serum IgA, fecal, intestinal, nasal IgA, and the serum interleukin-1β levels were higher in the Lactobacilli microsphere group compared with the blank microsphere and the lactobacilli solution group, suggesting that the Lactobacilli microspheres were more gastro-resistant and, hence, showed positive effects compared with the Lactobacilli solution. However, the Lactobacilli microspheres did not have a significant effect on the tumor necrosis factor-α levels. PMID:27044945

  9. Evaluation of the Intestinal Colonizing Potential and Immunomodulating Capacity of Lactobacilli Microspheres.

    PubMed

    Cotta, Karyn I; Addo, Richard T; D'Souza, Martin J

    2016-05-01

    Lactobacilli species get degraded by acidic conditions in the stomach. Thus, the objective of this study was to (1) formulate and characterize gastro-resistant Lactobacilli microspheres and (2) evaluate the ability of Lactobacilli microspheres to colonize the intestine and their capacity to have an immunomodulating effect in vivo. The product yield and the encapsulation efficiency were 45% and 100%, respectively. The average microsphere particle size was 5 μm. Lactobacilli microspheres were most stable at 4°C and showed a better suspendibility in distilled water. Without encapsulation, the viability of bacteria decreased within 30 min. In the case of Lactobacilli microspheres, no Lactobacilli were released in the first 3 h, and highest release was observed at 4 h, thus, suggesting the significance of encapsulation of Lactobacilli. Lactobacilli microspheres maintained intestinal colonization only during the dosing period, and the serum IgG, serum IgA, fecal, intestinal, nasal IgA, and the serum interleukin-1β levels were higher in the Lactobacilli microsphere group compared with the blank microsphere and the lactobacilli solution group, suggesting that the Lactobacilli microspheres were more gastro-resistant and, hence, showed positive effects compared with the Lactobacilli solution. However, the Lactobacilli microspheres did not have a significant effect on the tumor necrosis factor-α levels.

  10. Enhanced autonomic shutdown of Li-ion batteries by polydopamine coated polyethylene microspheres

    SciTech Connect

    Baginska, Marta; Blaiszik, Benjamin J.; Rajh, Tijana; Sottos, Nancy R.; White, Scott R.

    2014-07-17

    Thermally triggered autonomic shutdown of a Lithium-ion (Li-ion) battery is demonstrated using polydopamine (PDA)-coated polyethylene microspheres applied onto a battery anode. The microspheres are dispersed in a buffered 10 mM dopamine salt solution and the pH is raised to initiate the polymerization and coat the microspheres. Coated microspheres are then mixed with an aqueous binder, applied onto a battery anode surface, dried, and incorporated into Li-ion coin cells. FTIR and Raman spectroscopy are used to verify the presence of the polydopamine on the surface of the microspheres. Scanning electron microscopy is used to examine microsphere surface morphology and resulting anode coating quality. Charge and discharge capacity, as well as impedance, are measured for Li-ion coin cells as a function of microsphere content. Autonomous shutdown is achieved by applying 1.7 mg cm–2 of PDA-coated microspheres to the electrode. Furthermore, the PDA coating significantly reduces the mass of microspheres for effective shutdown compared to our prior work with uncoated microspheres.

  11. Enhanced autonomic shutdown of Li-ion batteries by polydopamine coated polyethylene microspheres

    DOE PAGES

    Baginska, Marta; Blaiszik, Benjamin J.; Rajh, Tijana; Sottos, Nancy R.; White, Scott R.

    2014-07-17

    Thermally triggered autonomic shutdown of a Lithium-ion (Li-ion) battery is demonstrated using polydopamine (PDA)-coated polyethylene microspheres applied onto a battery anode. The microspheres are dispersed in a buffered 10 mM dopamine salt solution and the pH is raised to initiate the polymerization and coat the microspheres. Coated microspheres are then mixed with an aqueous binder, applied onto a battery anode surface, dried, and incorporated into Li-ion coin cells. FTIR and Raman spectroscopy are used to verify the presence of the polydopamine on the surface of the microspheres. Scanning electron microscopy is used to examine microsphere surface morphology and resulting anodemore » coating quality. Charge and discharge capacity, as well as impedance, are measured for Li-ion coin cells as a function of microsphere content. Autonomous shutdown is achieved by applying 1.7 mg cm–2 of PDA-coated microspheres to the electrode. Furthermore, the PDA coating significantly reduces the mass of microspheres for effective shutdown compared to our prior work with uncoated microspheres.« less

  12. Assembly of ordered microsphere arrays: Platforms for microarrays

    NASA Astrophysics Data System (ADS)

    Xu, Wanling

    Microarrays are powerful tools in gene expression assessment, protein profiling, and protein function screening, as well as cell and tissue analysis. With thousands of small array spots assembled in an ordered array, these small devices makes it possible to screen for multiple targets in a fast, parallel, high-throughput manner. The well-developed technology of DNA microarrays, also called DNA chips, has proved successful in all kinds of biological experiments, including the human genome-sequencing project. The development of protein arrays has lagged behind that of DNA arrays mainly because of the greater complexity of proteins. Some parts of the microarray technology can be transplanted into the realm of protein arrays, while others cannot. The challenges from the complexity of protein targets demand more robust and powerful devices. Traditional planar arrays, in which proteins bind directly to a planar surface, have a drawback in that some proteins will be denatured or cluster together after immobilization. Microsphere-based microarrays represent a more advanced strategy. The functional proteins are first attached to microspheres; these microspheres are then immobilized in arrays on a planar surface. In this dissertation, two approaches to assembling arrays of microspheres will be discussed. The hydrodynamic approach uses surface micromachining and Deep Reactive Ion Etching techniques to form an array of channels through a silicon wafer. By drawing fluid containing the microspheres through the channels they become trapped in the channels and thereby immobilized. In the magnetic approach, permalloy films are deposited on a silicon substrate and subsequently patterned to form magnetic attachment sites. An external magnetic field is then applied and the magnetic microspheres then assemble on these sites. Both devices are able to immobilize microspheres in an ordered array, as opposed to coarsely grouping them in array spots. The assembled arrays are robust in that

  13. Preparation and drug controlled release of porous octyl-dextran microspheres.

    PubMed

    Hou, Xin; Liu, Yanfei

    2015-01-01

    In this work, porous octyl-dextran microspheres with excellent properties were prepared by two steps. Firstly, dextran microspheres were synthesized by reversed-phase suspension polymerization. Secondly, octyl-dextran microspheres were prepared by the reaction between dextran microspheres and ethylhexyl glycidyl ether and freezing-drying method. Porous structure of microspheres was formed through the interaction between octyl groups and organic solvents. The structure, morphology, dry density, porosity and equilibrium water content of porous octyl-dextran microspheres were systematically investigated. The octyl content affected the properties of microspheres. The results showed that the dry density of microspheres decreased from 2.35 to 1.21 g/ml, porosity increased from 80.68 to 95.05% with the octyl content increasing from 0.49 to 2.28 mmol/g. Meanwhile, the equilibrium water content presented a peak value (90.18%) when the octyl content was 2.25 mmol/g. Octyl-dextran microspheres showed high capacity. Naturally drug carriers play an important role in drug-delivery systems for their biodegradability, wide raw materials sources and nontoxicity. Doxorubicin (DOX) was used as a drug model to examine the drug-loading capacity of porous octyl-dextran microspheres. The drug-loading efficiency increased with the increase in microspheres/drug ratio, while the encapsulation efficiency decreased. When microspheres/drug mass ratio was 4/1, the drug-loading efficiency and encapsulation efficiency were 10.20 and 51.00%, respectively. The release rate of DOX increased as drug content and porosity increased. In conclusion, porous octyl-dextran microspheres were synthesized successfully and have the potential to serve as an effective delivery system in drug controlled release.

  14. Modeling human brain development with cerebral organoids.

    PubMed

    Muzio, Luca; Consalez, G Giacomo

    2013-01-01

    The recent discovery of a new three-dimensional culture system for the derivation of cerebral organoids from human induced pluripotent stem cells provides developmental neurobiologists with the first example of a three-dimensional framework for the study of human brain development. This innovative approach permits the in vitro assembly of a human embryonic brain rudiment that recapitulates the developing human cerebrum. Organoids contain progenitor populations that develop to yield mature cortical neuron subtypes, potentially allowing investigators to study complex brain diseases that lack appropriate animal models. PMID:24367992

  15. Novel biodegradable polyesteramide microspheres for controlled drug delivery in Ophthalmology.

    PubMed

    Andrés-Guerrero, Vanessa; Zong, Mengmeng; Ramsay, Eva; Rojas, Blanca; Sarkhel, Sanjay; Gallego, Beatriz; de Hoz, Rosa; Ramírez, Ana I; Salazar, Juan José; Triviño, Alberto; Ramírez, José M; Del Amo, Eva M; Cameron, Neil; de-Las-Heras, Beatriz; Urtti, Arto; Mihov, George; Dias, Aylvin; Herrero-Vanrell, Rocío

    2015-08-10

    Most of the posterior segment diseases are chronic and multifactorial and require long-term intraocular medication. Conventional treatments of these pathologies consist of successive intraocular injections, which are associated with adverse effects. Successful therapy requires the development of new drug delivery systems able to release the active substance for a long term with a single administration. The present work involves the description of a new generation of microspheres based on poly(ester amide)s (PEA), which are novel polymers with improved biodegradability, processability and good thermal and mechanical properties. We report on the preparation of the PEA polymer, PEA microspheres (PEA Ms) and their characterization. PEA Ms (~15μm) were loaded with a lipophilic drug (dexamethasone) (181.0±2.4μg DX/mg Ms). The in vitro release profile of the drug showed a constant delivery for at least 90days. Based on the data from a performed in vitro release study, a kinetic ocular model to predict in vivo drug concentrations in a rabbit vitreous was built. According to the pharmacokinetic simulations, intravitreal injection of dexamethasone loaded PEA microspheres would provide release of the drug in rabbit eyes up to 3months. Cytotoxicity studies in macrophages and retinal pigment epithelial cells revealed a good in vitro tolerance of the microsystems. After sterilization, PEA Ms were administered in vivo by subtenon and intravitreal injections in male Sprague-Dawley rats and the location of the microspheres in rat eyes was monitored. We conclude that PEA Ms provide an alternative delivery system for controlling the delivery of drugs to the eye, allowing a novel generation of microsphere design.

  16. Novel biodegradable polyesteramide microspheres for controlled drug delivery in Ophthalmology.

    PubMed

    Andrés-Guerrero, Vanessa; Zong, Mengmeng; Ramsay, Eva; Rojas, Blanca; Sarkhel, Sanjay; Gallego, Beatriz; de Hoz, Rosa; Ramírez, Ana I; Salazar, Juan José; Triviño, Alberto; Ramírez, José M; Del Amo, Eva M; Cameron, Neil; de-Las-Heras, Beatriz; Urtti, Arto; Mihov, George; Dias, Aylvin; Herrero-Vanrell, Rocío

    2015-08-10

    Most of the posterior segment diseases are chronic and multifactorial and require long-term intraocular medication. Conventional treatments of these pathologies consist of successive intraocular injections, which are associated with adverse effects. Successful therapy requires the development of new drug delivery systems able to release the active substance for a long term with a single administration. The present work involves the description of a new generation of microspheres based on poly(ester amide)s (PEA), which are novel polymers with improved biodegradability, processability and good thermal and mechanical properties. We report on the preparation of the PEA polymer, PEA microspheres (PEA Ms) and their characterization. PEA Ms (~15μm) were loaded with a lipophilic drug (dexamethasone) (181.0±2.4μg DX/mg Ms). The in vitro release profile of the drug showed a constant delivery for at least 90days. Based on the data from a performed in vitro release study, a kinetic ocular model to predict in vivo drug concentrations in a rabbit vitreous was built. According to the pharmacokinetic simulations, intravitreal injection of dexamethasone loaded PEA microspheres would provide release of the drug in rabbit eyes up to 3months. Cytotoxicity studies in macrophages and retinal pigment epithelial cells revealed a good in vitro tolerance of the microsystems. After sterilization, PEA Ms were administered in vivo by subtenon and intravitreal injections in male Sprague-Dawley rats and the location of the microspheres in rat eyes was monitored. We conclude that PEA Ms provide an alternative delivery system for controlling the delivery of drugs to the eye, allowing a novel generation of microsphere design. PMID:26003040

  17. FEMIC (Fibromes Embolises aux MICrospheres calibrees): Uterine Fibroid Embolization using Tris-acryl Microspheres. A French Multicenter Study

    SciTech Connect

    Joffre, Francis; Tubiana, Jean-Michel; Pelage, Jean-Pierre

    2004-11-15

    Purpose: A French multicenter registry was set up to confirm the safety and efficacy of large calibrated tris-acryl gelatin microspheres for embolization of symptomatic fibroids. Methods: Technical recommendations included embolization using large microspheres (>500 {mu}m) with no secondary embolization agent. Postprocedural pain, clinical improvement and adverse events were prospectively evaluated during a follow-up period of at least 6 months.Results: Eighty-five women complaining of fibroid-related symptoms entered the study. In seven women, a secondary embolization agent was used in addition to microspheres. Complete resolution of menorrhagia was achieved in 84% of women at 24 months and significant uterine and fibroid volume reductions were noted after 6 months (37% and 73%, respectively). Three women experienced definitive amenorrhea (4%) and two women required hysteroscopic resection of a fibroid. Eight women were treated by hysterectomy because of treatment failure. In seven of these women, treatment failure was explained by an additional cause of symptoms including diffuse adenomyosis, endometrial hyperplasia or ovarian artery supply to the fibroids.Conclusion: Limited uterine artery embolization using large microspheres has good clinical success rate with low postprocedural pain and complications. Women can expect excellent midterm results with a high level of symptom control and significant fibroid volume reduction. Confidence in the end-point recommended here may require the experience of several cases.

  18. Release mechanisms of tacrolimus-loaded PLGA and PLA microspheres and immunosuppressive effects of the microspheres in a rat heart transplantation model.

    PubMed

    Kojima, Ryo; Yoshida, Takatsune; Tasaki, Hiroaki; Umejima, Hiroyuki; Maeda, Masashi; Higashi, Yasuyuki; Watanabe, Shunsuke; Oku, Naoto

    2015-08-15

    The objective of this study was to elucidate the release and absorption mechanisms of tacrolimus loaded into microspheres composed of poly(lactic-co-glycolic acid) (PLGA) and/or polylactic acid (PLA). Tacrolimus-loaded microspheres were prepared by the o/w emulsion solvent evaporation method. The entrapment efficiency correlated with the molecular weight of PLGA, and the glass transition temperature of PLGA microspheres was not decreased by the addition of tacrolimus. These results indicate that intermolecular interaction between tacrolimus and the polymer would affect the entrapment of tacrolimus in the microspheres. Tacrolimus was released with weight loss of the microspheres, and the dominant release mechanism of tacrolimus was considered to be erosion of the polymer rather than diffusion of the drug. The whole-blood concentration of tacrolimus in rats was maintained for at least 2 weeks after a single subcutaneous administration of the microspheres. The pharmacokinetic profile of tacrolimus following subcutaneous administration was similar to that following intramuscular administration, suggesting that the release and dissolution of tacrolimus, rather than the absorption of the dissolved tacrolimus, were rate-limiting steps. Graft-survival time in a heart transplantation rat model was prolonged by the administration of tacrolimus-loaded microspheres. The microsphere formulation of tacrolimus would be expected to precisely control the blood concentration while maintaining the immunosuppressive effect of the drug.

  19. Hydrothermal synthesis and photocatalytic performance of hierarchical Bi{sub 2}MoO{sub 6} microspheres using BiOI microspheres as self-sacrificing templates

    SciTech Connect

    Xu, Ming; Zhang, Wei-De

    2015-07-15

    Bi{sub 2}MoO{sub 6} hierarchical microspheres were successfully prepared through phase transformation from BiOI microspheres with the assistance of sodium citrate under hydrothermal condition. The possible formation mechanism for the conversion of BiOI to Bi{sub 2}MoO{sub 6} is discussed here. After being annealed at 300 °C for 2 h, the obtained Bi{sub 2}MoO{sub 6} microspheres exhibited remarkably enhanced photocatalytic activity towards the degradation of rhodamine B and phenol. The superior catalytic performance can be attributed to its larger surface area and higher crystallinity. In addition, Bi{sub 2}MoO{sub 6} microspheres are stable during the degradation reaction and can be used repeatedly. - Graphical abstract: Bi{sub 2}MoO{sub 6} hierarchical microspheres were successfully prepared through a facile partial anion exchange strategy using BiOI microspheres as self-sacrificing templates. The Bi{sub 2}MoO{sub 6} microspheres show high visible light photocatalytic activity. - Highlights: • Bi{sub 2}MoO{sub 6} microspheres were prepared via self-sacrificing template anion exchange. • Sodium citrate-assisted anion exchange for preparation of Bi{sub 2}MoO{sub 6} photocatalyst. • Bi{sub 2}MoO{sub 6} catalysts show high visible light photocatalytic activity.

  20. Middle Cerebral Artery Calcification

    PubMed Central

    Kao, Hung-Wen; Liou, Michelle; Chung, Hsiao-Wen; Liu, Hua-Shan; Tsai, Ping-Huei; Chiang, Shih-Wei; Chou, Ming-Chung; Peng, Giia-Sheun; Huang, Guo-Shu; Hsu, Hsian-He; Chen, Cheng-Yu

    2015-01-01

    Abstract Calcification of the middle cerebral artery (MCA) is uncommon in the healthy elderly. Whether calcification of the MCA is associated with cerebral ischemic stroke remains undetermined. We intended to investigate the association using Agatston calcium scoring of the MCA. This study retrospectively included 354 subjects with ischemic stroke in the MCA territory and 1518 control subjects who underwent computed tomography (CT) of the brain. We recorded major known risk factors for ischemic stroke, including age, gender, hypertension, diabetes mellitus, smoking, hyperlipidemia, and obesity, along with the MCA calcium burden, measured with the Agatston calcium scoring method. Univariate and modified logistic regression analyses were performed to examine the association between the MCA calcification and ischemic stroke. The univariate analyses showed significant associations of ischemic stroke with age, hypertension, diabetes mellitus, smoking, total MCA Agatston score, and the presence of calcification on both or either side of the MCA. Subjects with the presence of MCA calcification on both or either side of the MCA were 8.46 times (95% confidence interval, 4.93–14.53; P < 0.001) more likely to have a cerebral infarct than subjects without MCA calcification after adjustment for the major known risk factors, including age, hypertension, diabetes mellitus, and smoking. However, a higher degree of MCA calcification reflected by the Agatston score was not associated with higher risk of MCA ischemic stroke after adjustment for the confounding factors and presence of MCA calcification. These results suggest that MCA calcification is associated with ischemic stroke in the MCA territory. Further prospective studies are required to verify the clinical implications of the MCA calcification. PMID:26683969

  1. Pediatric traumatic carotid, vertebral and cerebral artery dissections: a review.

    PubMed

    Mortazavi, Martin M; Verma, Ketan; Tubbs, R Shane; Harrigan, Mark

    2011-12-01

    Traumatic cerebral dissections are rare but potentially dangerous conditions that through improved diagnostics have recently gained increased interest. However, there is still a significant lack of knowledge on the natural history, as well as on the best treatment options. Most of the literature on this topic consists of case reports and retrospective studies with no prospective randomized controlled studies. In our review, we highlight the fact that there is no level 1 evidence for the natural history of cerebral dissections or for the best treatment. We present 26 case studies derived from 70 pediatric patients affected by dissections, occlusions, and pseudoaneurysms.

  2. Cerebral salt wasting syndrome.

    PubMed

    Uygun, M A; Ozkal, E; Acar, O; Erongun, U

    1996-01-01

    Hyponatremia following acute or chronic central nervous system injury which is due to excessive Na+ loss in the urine without an increase in the body fluid, has been described as Cerebral Salt Wasting Syndrome (CSWS). This syndrome is often confused with dilutional hyponatremia secondary to inappropriate ADH secretion. Accurate diagnosis and management are mandatory for to improve the course of the disease. In this study a patient with CSW Syndrome is presented and the treatment and diagnosis of this syndrome are discussed in view of the literature.

  3. Hemodynamics of Cerebral Aneurysms

    PubMed Central

    Sforza, Daniel M.; Putman, Christopher M.; Cebral, Juan Raul

    2009-01-01

    The initiation and progression of cerebral aneurysms are degenerative processes of the arterial wall driven by a complex interaction of biological and hemodynamic factors. Endothelial cells on the artery wall respond physiologically to blood-flow patterns. In normal conditions, these responses are associated with nonpathological tissue remodeling and adaptation. The combination of abnormal blood patterns and genetics predisposition could lead to the pathological formation of aneurysms. Here, we review recent progress on the basic mechanisms of aneurysm formation and evolution, with a focus on the role of hemodynamic patterns. PMID:19784385

  4. On-Flow Synthesis of Co-Polymerizable Oligo-Microspheres and Application in ssDNA Amplification

    PubMed Central

    Lee, Se Hee; Lee, Jae Ha; Lee, Ho Won; Kim, Yang-Hoon; Jeong, Ok Chan; Ahn, Ji-Young

    2016-01-01

    We fabricated droplet-based microfluidic platform for copolymerizable microspheres with acrydite modified DNA probe. The copolymerizable 3-D polyacrylamide microspheres were successfully produced from microcontinuous-flow synthesis with on-channel solidification. DNA copolymerization activity, surface presentation and thermostability were assessed by using fluorescent labeled complementary probe. The binding performance was only visible on the surface area of oligo-microspheres. We show that the resulting oligo-microspheres can be directly integrated into a streamlined microsphere-PCR protocol for amplifying ssDNA. Our microspheres could be utilized as a potential material for ssDNA analysis such as DNA microarray and automatic DNA SELEX process. PMID:27447941

  5. Engineered magnetic core-shell SiO2/Fe microspheres and "medusa-like" microspheres of SiO2/iron oxide/carbon nanofibers or nanotubes.

    PubMed

    Mero, On; Sougrati, Moulay-Tahar; Jumas, Jean-Claude; Margel, Shlomo

    2014-08-19

    Iron oxide (IO) thin coatings of controlled thickness on SiO2 microspheres of narrow size distribution were prepared by decomposition at 160 °C of triiron dodecacarbonyl onto silica microspheres dispersed in diethylene glycol diethyl ether free of surfactant or stabilizer. The dried washed SiO2/IO core-shell microspheres were annealed at different temperatures and time periods under inert (Ar) or reducing (H2) atmosphere. The effect of temperature on the chemical composition, morphology, crystallinity, and magnetic properties of the IO and the elemental Fe nanoparticles type coatings onto the SiO2 core microspheres has been elucidated. "Medusa-like" SiO2/IO/carbon nanofibers and tubes particles were prepared by CVD of ethylene on the surface of the SiO2/IO microspheres at different temperatures. The morphology change of the grafted carbon nanofibers and tubes as a function of the CVD temperature was also elucidated. PMID:25089849

  6. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials.

    PubMed

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-12-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  7. Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials

    NASA Astrophysics Data System (ADS)

    Chang, Jinghui; Zang, Linlin; Wang, Cheng; Sun, Liguo; Chang, Qing

    2016-02-01

    Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.

  8. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    DOEpatents

    Parans Paranthaman, Mariappan; Bi, Zhonghe; Bridges, Craig A; Brown, Gilbert M

    2014-12-16

    Compositions and methods of making are provided for treated mesoporous metal oxide microspheres electrodes. The compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g, and wherein the composition has an electrical conductivity of at least 1.times.10.sup.-7 S/cm at 25.degree. C. and 60 MPa. The methods of making comprise forming a mesoporous metal oxide microsphere composition and treating the mesoporous metal oxide microspheres by at least one method selected from the group consisting of: (i) annealing in a reducing atmosphere, (ii) doping with an aliovalent element, and (iii) coating with a coating composition.

  9. Silicon dioxide hollow microspheres with porous composite structure: synthesis and characterization.

    PubMed

    Yan, Xiuli; Lei, Zhongli

    2011-10-15

    In this paper, a strategy for hollow porous silica microspheres with ideally flower structure is presented. SiO(2)/PAM hybrid composite microspheres with porous were synthesized by the reaction that the porous polyacrylamide (PAM) micro-gels immersed in tetraethoxysilane (TEOS) anhydrous alcohol solution and water in a moist atmosphere, with ammonium hydroxide as a catalyst. The SiO(2) hollow microspheres with porous were obtained after calcination of the composite microspheres at 550 °C for 4 h. The morphology, composition, and crystalline structure of the microspheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FI-IR), and X-ray diffraction (XRD), N(2) absorption analysis, respectively. The results indicated that the obtained hollow porous SiO(2) microspheres were a perfect flower structure.

  10. MRI visible drug eluting magnetic microspheres for transcatheter intra-arterial delivery to liver tumors.

    PubMed

    Kim, Dong-Hyun; Chen, Jeane; Omary, Reed A; Larson, Andrew C

    2015-01-01

    Magnetic resonance imaging (MRI)-visible amonafide-eluting alginate microspheres were developed for targeted arterial-infusion chemotherapy. These alginate microspheres were synthesized using a highly efficient microfluidic gelation process. The microspheres included magnetic clusters formed by USPIO nanoparticles to permit MRI and a sustained drug-release profile. The biocompatibility, MR imaging properties and amonafide release kinetics of these microspheres were investigated during in vitro studies. A xenograft rodent model was used to demonstrate the feasibility to deliver these microspheres to liver tumors using hepatic transcatheter intra-arterial infusions and potential to visualize the intra-hepatic delivery of these microspheres to both liver tumor and normal tissues with MRI immediately after infusion. This approach offer the potential for catheter-directed drug delivery to liver tumors for reduced systemic toxicity and superior therapeutic outcomes.

  11. Aerogel microspheres from natural cellulose nanofibrils and their application as cell culture scaffold.

    PubMed

    Cai, Hongli; Sharma, Sudhir; Liu, Wenying; Mu, Wei; Liu, Wei; Zhang, Xiaodan; Deng, Yulin

    2014-07-14

    We demonstrated that ultralight pure natural aerogel microspheres can be fabricated using cellulose nanofibrials (CNF) directly. Experimentally, the CNF aqueous gel droplets, produced by spraying and atomizing through a steel nozzle, were collected into liquid nitrogen for instant freezing followed by freeze-drying. The aerogel microspheres are highly porous with bulk density as low as 0.0018 g cm(-3). The pore size of the cellulose aeogel microspheres ranges from nano- to macrometers. The unique ultralight and high porous structure ensured high moisture (~90 g g(-1)) and water uptake capacity (~100 g g(-1)) of the aerogel microspheres. Covalent cross-linking between the native nanofibrils and cross-linkers made the aerogel microspheres very stable even in a harsh environment. The present study also confirmed this kind of aerogel microspheres from native cellulose fibers can be used as cell culture scaffold.

  12. Monodisperse, polymeric microspheres produced by irradiation of slowly thawing frozen drops

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu (Inventor); Hyson, Michael T. (Inventor); Chung, Sang-Kun (Inventor); Colvin, Michael S. (Inventor); Chang, Manchium (Inventor)

    1991-01-01

    Monodisperse, polymeric microspheres are formed by injecting uniformly shaped droplets of radiation polymerizable monomers, preferably a biocompatible monomer, having covalent binding sites such as hydroxyethylmethacrylate, into a zone, impressing a like charge on the droplet so that they mutually repel each other, spheroidizing the droplets within the zone and collecting the droplets in a pool of cryogenic liquid. As the droplets enter the liquid, they freeze into solid, glassy microspheres, which vaporizes a portion of the cryogenic liquid to form a layer. The like-charged microspheres, suspended within the layer, move to the edge of the vessel holding the pool, are discharged, fall and are collected. The collected microspheres are irradiated while frozen in the cryogenic liquid to form latent free radicals. The frozen microspheres are then slowly thawed to activate the free radicals which polymerize the monomer to form evenly-sized, evenly-shaped, monodisperse polymeric microspheres.

  13. Preparation of monodisperse PEG hydrogel composite microspheres via microfluidic chip with rounded channels

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Cong, Hailin; Liu, Xuesong; Ren, Yumin; Wang, Jilei; Zhang, Lixin; Tang, Jianguo; Ma, Yurong; Akasaka, Takeshi

    2013-09-01

    An effective microfluidic method to fabricate monodisperse polyethylene glycol (PEG) hydrogel composite microspheres with tunable dimensions and properties is reported in this paper. A T-junction microfluidic chip equipped with rounded channels and online photopolymerization system is applied for the microsphere microfabrication. The shape and size of the microspheres are well controlled by the rounded channels and PEG prepolymer/silicon oil flow rate ratios. The obtained PEG/aspirin composite microspheres exhibit a sustained release of aspirin for a wide time range; the obtained PEG/Fe3O4 nanocomposite microspheres exhibit excellent magnetic properties; and the obtained binary PEG/dye composite microspheres show the ability to synchronously load two functional components in the same peanut-shaped or Janus hydrogel particles.

  14. Preparation and evaluation of glyceryl monooleate-coated hollow-bioadhesive microspheres for gastroretentive drug delivery.

    PubMed

    Liu, Yuanfen; Zhang, Jianjun; Gao, Yuan; Zhu, Jiabi

    2011-07-15

    The purpose of this study was to produce hollow and bioadhesive microspheres to lengthen drug retention time in the stomach. In these microspheres, ethylcellulose was used as the matrix, Eudragit EPO was employed to modulate the release rate, and glyceryl monooleate (GMO) was the bioadhesive polymer in situ. The morphological characteristics of the microspheres were defined using scanning electron microscopy. The in vitro release test showed that the release rate of drug from the microspheres was pH-dependent, and was not influenced by the GMO coating film. The prepared microspheres demonstrated strong mucoadhesive properties with good buoyancy both in vitro and in vivo. Pharmacokinetic analysis indicated that the elimination half-life time of the hollow-bioadhesive microspheres was prolonged, and that the elimination rate was decreased. In conclusion, the hollow-bioadhesive synergic drug delivery system may be advantageous in the treatment of stomach diseases.

  15. Cerebral blood flow velocity in two patients with neonatal cerebral infarction.

    PubMed

    Nishimaki, S; Seki, K; Yokota, S

    2001-04-01

    Cerebral blood flow velocity was measured in the middle cerebral artery of two patients who exhibited unilateral neonatal cerebral infarction during the neonatal period. Doppler studies demonstrated increases in cerebral blood flow velocity but decreases in the resistance index on the affected side of the middle cerebral artery in the neonate who developed hemiplegia with cystic encephalomalacia, although the neonate with normal neurologic outcome exhibited symmetric cerebral blood flow velocity and resistance index. The asymmetry in cerebral blood flow velocity measurements of both middle cerebral arteries may be useful to evaluate the severity of brain damage and predict the neurodevelopmental prognosis of unilateral neonatal cerebral infarction. PMID:11377112

  16. Cerebral cartography and connectomics.

    PubMed

    Sporns, Olaf

    2015-05-19

    Cerebral cartography and connectomics pursue similar goals in attempting to create maps that can inform our understanding of the structural and functional organization of the cortex. Connectome maps explicitly aim at representing the brain as a complex network, a collection of nodes and their interconnecting edges. This article reflects on some of the challenges that currently arise in the intersection of cerebral cartography and connectomics. Principal challenges concern the temporal dynamics of functional brain connectivity, the definition of areal parcellations and their hierarchical organization into large-scale networks, the extension of whole-brain connectivity to cellular-scale networks, and the mapping of structure/function relations in empirical recordings and computational models. Successfully addressing these challenges will require extensions of methods and tools from network science to the mapping and analysis of human brain connectivity data. The emerging view that the brain is more than a collection of areas, but is fundamentally operating as a complex networked system, will continue to drive the creation of ever more detailed and multi-modal network maps as tools for on-going exploration and discovery in human connectomics.

  17. [Noradrenaline and cerebral aging].

    PubMed

    Jouvet, M; Albarede, J L; Lubin, S; Meyrignac, C

    1991-01-01

    The central functions of norepinephrine (NE) are a recent discovery: regulation of alertness and of the wakefulness-sleep cycle, maintenance of attention, memory and learning, cerebral plasticity and neuro-protection. The anatomical, histological, biochemical and physiological properties of the central noradrenergic system: extreme capacity for ramification and arborization; slow conduction, non-myelinized axons with extrasynaptic varicosities producing and releasing NE; frequency of co-transmission phenomena, and; neuromodulation with fiber effect responsible for improvement in the signal over background noise ratio and selection of significant stimuli form a true interface between the outside world and the central nervous system, notably for the neocortex in the context of the cognitive treatment of information. This central noradrenergic system is involved in the neurophysiology and the clinical features of cerebral aging (ideation-motor and cognitive function slowing down, loss of behavioral adjustment), neuro-degenerative disorders (SDAT, Parkinson's disease), certain aspects of depression and less obvious conditions (head injuries, sequelae of cerebrovascular accidents, sub-cortical dementia). The recent development of medications improving alertness (adrafinil, modafinil) with a pure central action and specifically noradrenergic, may contribute to an improvement in these multifactorial disorders. PMID:1864252

  18. Cerebral sinus venous thrombosis

    PubMed Central

    Alvis-Miranda, Hernando Raphael; Milena Castellar-Leones, Sandra; Alcala-Cerra, Gabriel; Rafael Moscote-Salazar, Luis

    2013-01-01

    Cerebral sinus venous thrombosis (CSVT) is a rare phenomenon that can be seen with some frequency in young patients. CSVT is a multifactorial condition with gender-related specific causes, with a wide clinical presentation, the leading causes differ between developed and developing countries, converting CSVT in a condition characterized by a highly variable clinical spectra, difficult diagnosis, variable etiologies and prognosis that requires fine medical skills and a high suspicious index. Patients who presents with CSVT should underwent to CT-scan venography (CVT) and to the proper inquiry of the generating cause. This disease can affect the cerebral venous drainage and related anatomical structure. The symptoms may appear in relation to increased intracranial pressure imitating a pseudotumorcerebri. Prognosis depends on the early detection. Correcting the cause, generally the complications can be prevented. Mortality trends have diminished, and with the new technologies, surely it will continue. This work aims to review current knowledge about CSVT including its pathogenesis, etiology, clinical manifestations, diagnosis, and treatment. PMID:24347950

  19. What constitutes cerebral palsy?

    PubMed

    Badawi, N; Watson, L; Petterson, B; Blair, E; Slee, J; Haan, E; Stanley, F

    1998-08-01

    Cerebral palsy (CP) is a term of convenience applied to a group of motor disorders of central origin defined by clinical description. It is not a diagnosis in that its application infers nothing about pathology, aetiology, or prognosis. It is an umbrella term covering a wide range of cerebral disorders which result in childhood motor impairment. The precise inclusion criteria vary with the objectives for using the term. For meaningful comparison of rates of CP, as performed by and between CP registers, it is important that the rates should be generated using the same criteria. As generally understood there must be motor impairment, and this impairment must stem from a malfunction of the brain (rather than spinal cord or muscles). Furthermore, the brain malfunction must be non-progressive and it must be manifest early in life. For the purposes of comparisons of rates across time even when the condition meets all the above criteria, it must not historically have been excluded from the category of CP. This paper addresses the problem of standardizing the inclusion criteria for selecting people included on CP registers with particular reference to this last criterion. PMID:9746004

  20. Facile synthesis of monodisperse porous Co3O4 microspheres with superior ethanol sensing properties.

    PubMed

    Sun, Chunwen; Rajasekhara, Shreyas; Chen, Yujin; Goodenough, John B

    2011-12-28

    A solvothermal method was developed to prepare on a large scale monodisperse porous β-Co(OH)(2) microspheres consisting of nanoplatelets. Co(3)O(4) microspheres with porous platelets were obtained via subsequent thermal decomposition. These Co(3)O(4) microspheres show much higher ethanol sensitivity and selectivity at a relatively low temperature (135 °C) compared with those of commercial Co(3)O(4) nanoparticles.

  1. Magnetic targeting of a therapeutic antibody using magnetotropic microspheres of the interpolyelectrolyte coacervation complex

    NASA Astrophysics Data System (ADS)

    B. Kirpotin, Dmitri; Kinne, Raimund; Milton, Andrew; Palombo-Kinne, Ernesta; Emmrich, Frank

    1993-04-01

    The therapeutic monoclonal anti-rat CD4 antibody OX35 was successfully localized in the ankle joint of arthritic rats in vivo using a permanent magnet and magnetotropic microspheres composed of a protamine-chondroitin sulphate complex. The microspheres formed at nearly stoichiometric quantities of the polyelectrolytes and quantitatively incorporated both magnetite and antibody. The release of immunologically active antibody from the microspheres was controlled by glutaraldehyde treatment.

  2. Method and apparatus for controlled size distribution of gel microspheres formed from aqueous dispersions

    DOEpatents

    Ryon, Allen D.; Haas, Paul A.; Vavruska, John S.

    1984-01-01

    The present invention is directed to a method and apparatus for making a population of dense, closely size-controlled microspheres by sol-gel procedures wherein said microspheres are characterized by a significant percentage of said population being within a predetermined, relatively narrow size range. Microsphere populations thus provided are useful in vibratory-packed processes for nuclear fuels to be irradiated in LWR- and FBR-type nuclear reactors.

  3. Surface Modification of Polydivinylbenzene Microspheres with a Fluorinated Glycopolymer Using Thiol-Halogen Click Chemistry.

    PubMed

    Song, Wentao; Granville, Anthony M

    2016-01-01

    Distillation-precipitation polymerization of divinylbenzene was applied to obtain uniform-sized polymeric microspheres. The microspheres were then modified with polypentafluorostyrene chains utilizing surface-initiated atom transfer radical polymerization techniques. The hydrophobic fluoropolymer-coated microsphere was then converted to a hydrophilic biopolymer by performing thiol-halogen click chemistry between polypentafluorostyrene and 1-thio-β-D-glucose sodium salt. The semi-fluorinated glycopolymer showed good binding ability with Concanavalin A as determined by confocal microscopy and turbidity experiments.

  4. The Effect of Melatonin Adsorbed to Polyethylene Glycol Microspheres on the Survival of MCF-7 Cells.

    PubMed

    França, Eduardo Luzía; Honorio-França, Adenilda Cristina; Fernandes, Rubian Trindade da Silva; Marins, Camila Moreira Ferreira; Pereira, Claudia Cristina de Souza; Varotti, Fernando de Pilla

    2016-01-01

    Although melatonin exhibits oncostatic properties such as antiproliferative effects, the oral bioavailability of this hormone is less than 20%. Modified drug release systems have been used to improve the pharmacological efficiency of drugs. These systems can change the pharmacokinetics and biodistribution of the associated drugs. Thus, this study investigated the effect of melatonin adsorbed to polyethylene glycol (PEG) microspheres on MCF-7 human breast cancer cells. The MCF-7 cells were obtained from the American Type Culture Collection. MCF-7 cells were preincubated for 24 h with or without melatonin (100 ng/ml), PEG microspheres or melatonin adsorbed to PEG microspheres (100 ng/ml). Viability, intracellular calcium release and apoptosis in MCF-7 cells were determined by flow cytometry. MCF-7 cells incubated with melatonin adsorbed to PEG microspheres showed a lower viability rate (40.0 ± 8.3 with melatonin adsorbed to PEG microspheres compared to 54.1 ± 7.3 with melatonin; 81.8 ± 12.5 with PEG microsphere and 92.7 ± 4.1 with medium), increased spontaneous intracellular Ca2+ release (27.0 ± 8.6 with melatonin adsorbed to PEG microspheres compared to 21.5 ± 13.4 with melatonin; 10.1 ± 5.4 with PEG microsphere and 9.1 ± 5.6 with medium) and increased apoptosis index (51.2 ± 2.7 with melatonin adsorbed to PEG microspheres compared to 36.0 ± 2.1 with melatonin; 4.9 ± 0.5 with PEG microsphere and 3.1 ± 0.6 with medium). The results indicate that melatonin adsorbed to PEG microspheres exerts antitumor effects on human MCF-7 breast cancer cells. However, clinical tests must be performed to confirm the use of melatonin adsorbed to PEG microspheres as an alternative therapy against cancer. PMID:26445481

  5. Computer Modeling of Yttrium-90-Microsphere Transport in the Hepatic Arterial Tree to Improve Clinical Outcomes

    SciTech Connect

    Kennedy, Andrew S.; Kleinstreuer, Clement; Basciano, Christopher A.; Dezarn, William A.

    2010-02-01

    Purpose: Radioembolization (RE) via yttrium-90 ({sup 90}Y) microspheres is an effective and safe treatment for unresectable liver malignancies. However, no data are available regarding the impact of local blood flow dynamics on {sup 90}Y-microsphere transport and distribution in the human hepatic arterial system. Methods and Materials: A three-dimensional (3-D) computer model was developed to analyze and simulate blood-microsphere flow dynamics in the hepatic arterial system with tumor. Supplemental geometric and flow data sets from patients undergoing RE were also available to validate the accuracy of the computer simulation model. Specifically, vessel diameters, curvatures, and branching patterns, as well as blood flow velocities/pressures and microsphere characteristics (i.e., diameter and specific gravity), were measured. Three-dimensional computer-aided design software was used to create the vessel geometries. Initial trials, with 10,000 noninteracting microspheres released into the hepatic artery, used resin spheres 32-{mu}m in diameter with a density twice that of blood. Results: Simulations of blood flow subject to different branch-outlet pressures as well as blood-microsphere transport were successfully carried out, allowing testing of two types of microsphere release distributions in the inlet plane of the main hepatic artery. If the inlet distribution of microspheres was uniform (evenly spaced particles), a greater percentage would exit into the vessel branch feeding the tumor. Conversely, a parabolic inlet distribution of microspheres (more particles around the vessel center) showed a high percentage of microspheres exiting the branch vessel leading to the normal liver. Conclusions: Computer simulations of both blood flow patterns and microsphere dynamics have the potential to provide valuable insight on how to optimize {sup 90}Y-microsphere implantation into hepatic tumors while sparing normal tissue.

  6. Cerebral organoids model human brain development and microcephaly.

    PubMed

    Lancaster, Madeline A; Renner, Magdalena; Martin, Carol-Anne; Wenzel, Daniel; Bicknell, Louise S; Hurles, Matthew E; Homfray, Tessa; Penninger, Josef M; Jackson, Andrew P; Knoblich, Juergen A

    2013-09-19

    The complexity of the human brain has made it difficult to study many brain disorders in model organisms, highlighting the need for an in vitro model of human brain development. Here we have developed a human pluripotent stem cell-derived three-dimensional organoid culture system, termed cerebral organoids, that develop various discrete, although interdependent, brain regions. These include a cerebral cortex containing progenitor populations that organize and produce mature cortical neuron subtypes. Furthermore, cerebral organoids are shown to recapitulate features of human cortical development, namely characteristic progenitor zone organization with abundant outer radial glial stem cells. Finally, we use RNA interference and patient-specific induced pluripotent stem cells to model microcephaly, a disorder that has been difficult to recapitulate in mice. We demonstrate premature neuronal differentiation in patient organoids, a defect that could help to explain the disease phenotype. Together, these data show that three-dimensional organoids can recapitulate development and disease even in this most complex human tissue.

  7. Cerebral organoids model human brain development and microcephaly

    PubMed Central

    Lancaster, Madeline A.; Renner, Magdalena; Martin, Carol-Anne; Wenzel, Daniel; Bicknell, Louise S.; Hurles, Matthew E.; Homfray, Tessa; Penninger, Josef M.; Jackson, Andrew P.; Knoblich, Juergen A.

    2013-01-01

    The complexity of the human brain has made it difficult to study many brain disorders in model organisms, and highlights the need for an in vitro model of human brain development. We have developed a human pluripotent stem cell-derived 3D organoid culture system, termed cerebral organoid, which develops various discrete though interdependent brain regions. These include cerebral cortex containing progenitor populations that organize and produce mature cortical neuron subtypes. Furthermore, cerebral organoids recapitulate features of human cortical development, namely characteristic progenitor zone organization with abundant outer radial glial stem cells. Finally, we use RNAi and patient-specific iPS cells to model microcephaly, a disorder that has been difficult to recapitulate in mice. We demonstrate premature neuronal differentiation in patient organoids, a defect that could explain the disease phenotype. Our data demonstrate that 3D organoids can recapitulate development and disease of even this most complex human tissue. PMID:23995685

  8. Microsphere translocation and immunopotentiation in systemic tissues following intranasal administration.

    PubMed

    Eyles, J E; Bramwell, V W; Williamson, E D; Alpar, H O

    2001-09-14

    With a view to developing improved mucosal immunisation strategies, we have quantitatively investigated the uptake of fluorescent polystyrene carboxylate microspheres (1.1 microm diameter), using histology and fluorescence-activated cell sorting, following intranasal delivery to BALB/c mice. To qualify these biodistribution data, antigen specific memory and effector responses in the spleens of mice immunised nasally with Yersinia pestis V antigen loaded poly(lactide) (PLA) microspheres (1.5 microm diameter) were assessed at 4, 7 and 11 days. Irrespective of administration vehicle volume (10 or 50 microl), appreciable numbers of fluorescent microspheres were detected within nasal associated lymphoid tissues (NALT) and draining cervical lymph nodes. Nasal administration of the particles suspended in 50 microl volumes of phosphate-buffered saline (PBS) served to deposit the fluorescent microspheres throughout the respiratory tract (P<0.05). In these animals, appreciable particle uptake into the mediastinal lymph node was noted (P<0.05). Also, spleens removed from mice 10 days after fluorescent particle application contained significantly more microspheres if the suspension had been nasally instilled using a 50 microl volume (P<0.05). Appreciable memory (and effector from day 7) responses were detected in mediastinal lymph nodes removed from mice immunised nasally with 50 microl volumes of microparticulated or soluble V antigen. Immunological responses in splenic tissue removed 7 days after intranasal immunisation corroborated the thesis that the spleen can act as an inductive site following bronchopulmonary deposition of particulated antigen: upon exposure to V in vitro, splenic T-cells from mice nasally immunised with 50 microl volumes of microspheres incorporated statistically greater (P<0.05) quantities of [3H]thymidine into newly synthesised DNA than did T-cells from cohorts nasally immunised with 50 microl volumes of V in solution. Similarly, significant numbers

  9. Method for selecting hollow microspheres for use in laser fusion targets

    DOEpatents

    Farnum, Eugene H.; Fries, R. Jay; Havenhill, Jerry W.; Smith, Maurice Lee; Stoltz, Daniel L.

    1976-01-01

    Hollow microspheres having thin and very uniform wall thickness are useful as containers for the deuterium and tritium gas mixture used as a fuel in laser fusion targets. Hollow microspheres are commercially available; however, in commercial lots only a very small number meet the rigid requirements for use in laser fusion targets. Those meeting these requirements may be separated from the unsuitable ones by subjecting the commercial lot to size and density separations and then by subjecting those hollow microspheres thus separated to an external pressurization at which those which are aspherical or which have nonuniform walls are broken and separating the sound hollow microspheres from the broken ones.

  10. Practical Tantalum Coating of Microspheres for Experimental Visualization under Fluoroscopy and CT.

    PubMed

    Horikawa, Masahiro; Ishikawa, Masaki; Uchida, Barry T; Kaufman, John A; Farsad, Khashayar

    2016-01-01

    The present report describes a simple technique for tantalum coating of microspheres for visualization by fluoroscopy and computed tomography (CT). Spherical microspheres were soaked with Ta powder under different conditions and microscopically evaluated for Ta-coating quality by assessing bound and unbound Ta. For 100-300-µm Embosphere particles, soaking with 0.05 mL Ta powder for 30 minutes and centrifugation at 500 rpm produced optimal coating. Optimized microspheres were injected in swine renal arteries and assessed by fluoroscopy and micro-CT for the opacification of segmental, arcuate, and interlobular arteries. This practical method can be used for experimental studies with commonly available microspheres.

  11. [Relation between drug release and the drug status within curcumin-loaded microsphere].

    PubMed

    Chen, De; Liu, Yi; Fan, Kai-yan; Xie, Yi-qiao; Yu, An-an; Xia, Zi-hua; Yang, Fan

    2016-01-01

    To study the relation between drug release and the drug status within curcumin-loaded microsphere, SPG (shirasu porous glass) membrane emulsification was used to prepare the curcumin-PLGA (polylactic-co-glycolic acid) microspheres with three levels of drug loading respectively, and the in vitro release was studied with high-performance liquid chromatography (HPLC). The morphology of microspheres was observed with scanning electron microscopy (SEM), and the drug status was studied with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and infrared analysis (IR). The drug loading of microspheres was (5.85 ± 0.21)%, (11.71 ± 0.39)%, (15.41 ± 0.40)%, respectively. No chemical connection was found between curcumin and PLGA. According to the results of XRD, curcumin dispersed in PLGA as amorphous form within the microspheres of the lowest drug loading, while (2.12 ± 0.64)% and (5.66 ± 0.07)% curcumin crystals was detected in the other two kinds of microspheres, respectively, indicating that the drug status was different within three kinds of microspheres. In the data analysis, we found that PLGA had a limited capacity of dissolving curcumin. When the drug loading exceeded the limit, the excess curcumin would exist in the form of crystals in microspheres independently. Meanwhile, this factor contributes to the difference in drug release behavior of the three groups of microspheres. PMID:27405176

  12. Facile synthesis of vanadium oxide microspheres for lithium-ion battery cathodes

    NASA Astrophysics Data System (ADS)

    Fei, Hailong; Feng, Wenjing; Lin, Yunsheng

    2016-05-01

    A simple and versatile method for preparation of non-solid and solid V2O5 microspheres is developed. Non-solid and solid V2O5 microspheres can be controllably prepared via adjusting the mixed solvent volume ratio and reaction time at low temperature. Solid V2O5 microspheres display higher discharge capacity and better cycling performance than non-solid V2O5 microspheres as a cathode material for lithium-ion batteries, which is ascribed to smaller charge transfer and diffusion resistance.

  13. Preparation, structure, and in vitro chemical durability of yttrium phosphate microspheres for intra-arterial radiotherapy.

    PubMed

    Kawashita, Masakazu; Matsui, Naoko; Li, Zhixia; Miyazaki, Toshiki; Kanetaka, Hiroyasu

    2011-10-01

    Chemically durable microspheres containing yttrium and/or phosphorus are useful for intra-arterial radiotherapy. In this study, we attempted to prepare yttrium phosphate (YPO₄) microspheres with high chemical durability. YPO₄ microspheres with smooth surfaces and diameters of around 25 μm were successfully obtained when gelatin droplets containing yttrium and phosphate ions were cooled and solidified in a water-in-oil emulsion and then heat-treated at 1100°C. The chemical durability of the heat-treated microspheres in a simulated body fluid at pH = 6 and 7 was high enough for clinical application of intra-arterial radiotherapy.

  14. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications.

    PubMed

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R

    2016-03-23

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0-87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI.

  15. Preparation of magnetic polylactic acid microspheres and investigation of its releasing property for loading curcumin

    NASA Astrophysics Data System (ADS)

    Li, Fengxia; Li, Xiaoli; Li, Bin

    2011-11-01

    In order to obtain a targeting drug carrier system, magnetic polylactic acid (PLA) microspheres loading curcumin were synthesized by the classical oil-in-water emulsion solvent-evaporation method. In the Fourier transform infrared spectra of microspheres, the present functional groups of PLA were all kept invariably. The morphology and size distribution of magnetic microspheres were observed with scanning electron microscopy and dynamic light scattering, respectively. The results showed that the microspheres were regularly spherical and the surface was smooth with a diameter of 0.55-0.75 μm. Magnetic Fe 3O 4 was loaded in PLA microspheres and the content of magnetic particles was 12 wt% through thermogravimetric analysis. The magnetic property of prepared microspheres was measured by vibrating sample magnetometer. The results showed that the magnetic microspheres exhibited typical superparamagnetic behavior and the saturated magnetization was 14.38 emu/g. Through analysis of differential scanning calorimetry, the curcumin was in an amorphous state in the magnetic microspheres. The drug loading, encapsulation efficiency and releasing properties of curcumin in vitro were also investigated by ultraviolet-visible spectrum analysis. The results showed that the drug loading and encapsulation efficiency were 8.0% and 24.2%, respectively. And curcumin was obviously slowly released because the cumulative release percentage of magnetic microspheres in the phosphate buffer (pH=7.4) solution was only 49.01% in 72 h, and the basic release of curcumin finished in 120 h.

  16. Adaptable Poly(ethylene glycol) Microspheres Capable of Mixed-mode Degradation

    PubMed Central

    Parlato, Matthew; Johnson, Alexander; Hudalla, Gregory A.; Murphy, William L.

    2013-01-01

    Here we present a simple, degradable PEG microsphere system formed from a water-in-water emulsion process. Microsphere network degradation and erosion were controlled by adjusting the number of hydrolytically labile sites, by varying the PEG molecular weight, and by adjusting the emulsion conditions. Microsphere size was also controllable by adjusting the polymer formulation. Furthermore, we demonstrate that alternative degradation and erosion mechanisms, such as proteolytic degradation, can be incorporated into PEG microspheres, resulting in mixed-mode degradation. Due to the adaptability of this approach, it may serve as an attractive option for emerging tissue engineering, drug delivery, and gene delivery applications. PMID:23958780

  17. Facile preparation of multifunctional superparamagnetic PHBV microspheres containing SPIONs for biomedical applications

    PubMed Central

    Li, Wei; Jan Zaloga; Ding, Yaping; Liu, Yufang; Janko, Christina; Pischetsrieder, Monika; Alexiou, Christoph; Boccaccini, Aldo R.

    2016-01-01

    The promising potential of magnetic polymer microspheres in various biomedical applications has been frequently reported. However, the surface hydrophilicity of superparamagnetic iron oxide nanoparticles (SPIONs) usually leads to poor or even failed encapsulation of SPIONs in hydrophobic polymer microspheres using the emulsion method. In this study, the stability of SPIONs in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) solution was significantly increased after surface modification with lauric acid. As a result, magnetic PHBV microspheres with high encapsulation efficiencies (71.0–87.4%) were prepared using emulsion-solvent extraction/evaporation method. Magnetic resonance imaging (MRI) showed significant contrast for the magnetic PHBV microspheres. The toxicity of these magnetic PHBV microspheres towards human T-lymphoma suspension cells and adherent colon carcinoma HT-29 cells was investigated using flow cytometry, and they were shown to be non-toxic in a broad concentration range. A model drug, tetracycline hydrochloride, was used to demonstrate the drug delivery capability and to investigate the drug release behavior of the magnetic PHBV microspheres. The drug was successfully loaded into the microspheres using lauric acid-coated SPIONs as drug carrier, and was released from the microspheres in a diffusion controlled manner. The developed magnetic PHBV microspheres are promising candidates for biomedical applications such as targeted drug delivery and MRI. PMID:27005428

  18. Design and characterization of chitosan-alginate microspheres for ocular delivery of azelastine.

    PubMed

    Shinde, Ujwala A; Shete, Jaykumar N; Nair, Hema A; Singh, Kavita H

    2014-11-01

    The use of mucoadhesive biopolymers is one of the best approaches to prolong the drug residence inside the cul-de-sac, consequently increasing the bioavailability. Thus, the focus of this work was to develop mucoadhesive microspheres to overcome the limitations of ocular drug delivery. The chitosan-sodium alginate microspheres of azelastine hydrochloride were fabricated using modified ionotropic gelation technique. The particle size, zeta potential, entrapment efficiency and drug release kinetics were evaluated and characterized by SEM, FT-IR, DSC, in vitro mucoadhesion and in vivo study. The microspheres had average particle size in the range of 3.55 to 6.70 µm and zeta potential +24.55 to +49.56 mV. The fabricated microspheres possess maximum drug entrapment of 73.05% with 65% mucin binding efficiency and revealed a controlled release over the 8-h period following a non-Fickian diffusion. SEM showed that microspheres were distinct solid with irregular shape. FT-IR and DSC results concluded the drug entrapment into microspheres. In vivo studies on ocular rat model revealed that azelastine microspheres had better efficacy. Chitosan sodium alginate microspheres prepared were in particle size range suitable for ocular purpose. In vitro release and in vivo efficacy studies revealed that the microspheres were effective in prolonging the drug's presence in cul de sac with improved therapeutic efficacy. PMID:24032373

  19. Preparation of chitosan/nano hydroxyapatite organic-inorganic hybrid microspheres for bone repair.

    PubMed

    Chen, Jingdi; Pan, Panpan; Zhang, Yujue; Zhong, Shengnan; Zhang, Qiqing

    2015-10-01

    In this work, we encapsulated icariin (ICA) into chitosan (CS)/nano hydroxyapatite (nHAP) composite microspheres to form organic-inorganic hybrid microspheres for drug delivery carrier. The composition and morphology of composite microspheres were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry- thermogravimetric analysis (DSC-TGA). Moreover, we further studied the performance of swelling properties, degradation properties and drug release behavior of the microspheres. ICA, the extract of traditional Chinese medicine-epimedium, was combined to study drug release properties of the microspheres. ICA loaded microspheres take on a sustained release behavior, which can be not only ascribed to electrostatic interaction between reactive negative hydroxyl (OH) of ICA and positive amine groups (NH₂) of CS, but also depended on the homogeneous dispersion of HAP nanoparticles inside CS organic matrix. In addition, the adhesion and morphology of osteoblasts were detected by inverted fluorescence microscopy. The biocompatibility of CS/nHAP/ICA microspheres was evaluated by the MTT cytotoxicity assay, Hoechst 33258 and PI fluorescence staining. These studies demonstrate that composite microspheres provide a suitable microenvironment for osteoblast attachment and proliferation. It can be speculated that the ICA loaded CS-based organic-inorganic hybrid microspheres might have potential applications in drug delivery systems.

  20. Effects of adding resorbable chitosan microspheres to calcium phosphate cements for bone regeneration.

    PubMed

    Meng, Dan; Dong, Limin; Wen, Ying; Xie, Qiufei

    2015-02-01

    Calcium phosphate cements (CPCs) have been widely used as bone graft substitutes. However, the undesirable osteoinductivity and slow degradability of CPCs greatly hamper their clinical application. The aim of this study was to synthesize a type of injectable, bioactive cement. This was accomplished by incorporating chitosan microspheres into CPC. CPC containing chitosan microspheres was analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD showed that the hardened chitosan microsphere/CPC with different proportions of microspheres contained diffraction peaks of hydroxyapatite and chitosan. Compressive strength and dissolution in simulated body fluid were measured. The chitosan microsphere/CPC containing 10% (w/w) chitosan microspheres had a compressive strength of 14.78 ± 0.67 MPa. Cavity defects were created in both femoral condylar regions of New Zealand White rabbits. Chitosan microsphere/CPC (composite group) and α-TCP/CPC (control group) were implanted separately into the bone defects of both femurs. X-ray analysis was performed to observe the filling of these bone defects 3 days after surgery. The extent of bone substitute degradation and new bone formation were evaluated by SEM and histological examination at 8, 16, and 24 weeks after implantation. These results showed far more new bone formation and degradation of the chitosan microsphere/CPC composite in the bone defects. These data indicate that a chitosan microsphere/CPC composite might be considered as a promising injectable material for the generation of new bone tissue.