956 resultados para Accretion disc


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Radiculopathy, a painful neuroinflammation that can accompany intervertebral disc herniation, is associated with locally increased levels of the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα). Systemic administration of TNF antagonists for radiculopathy in the clinic has shown mixed results, and there is growing interest in the local delivery of anti-inflammatory drugs to treat this pathology as well as similar inflammatory events of peripheral nerve injury. Curcumin, a known antagonist of TNFα in multiple cell types and tissues, was chemically modified and conjugated to a thermally responsive elastin-like polypeptide (ELP) to create an injectable depot for sustained, local delivery of curcumin to treat neuroinflammation. ELPs are biopolymers capable of thermally-triggered in situ depot formation that have been successfully employed as drug carriers and biomaterials in several applications. ELP-curcumin conjugates were shown to display high drug loading, rapidly release curcumin in vitro via degradable carbamate bonds, and retain in vitro bioactivity against TNFα-induced cytotoxicity and monocyte activation with IC50 only two-fold higher than curcumin. When injected proximal to the sciatic nerve in mice via intramuscular (i.m.) injection, ELP-curcumin conjugates underwent a thermally triggered soluble-insoluble phase transition, leading to in situ formation of a depot that released curcumin over 4days post-injection and decreased plasma AUC 7-fold.

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Mechanical stimuli are important factors that regulate cell proliferation, survival, metabolism and motility in a variety of cell types. The relationship between mechanical deformation of the extracellular matrix and intracellular deformation of cellular sub-regions and organelles has not been fully elucidated, but may provide new insight into the mechanisms involved in transducing mechanical stimuli to biological responses. In this study, a novel fluorescence microscopy and image analysis method was applied to examine the hypothesis that mechanical strains are fully transferred from a planar, deformable substrate to cytoplasmic and intranuclear regions within attached cells. Intracellular strains were measured in cells derived from the anulus fibrosus of the intervertebral disc when attached to an elastic silicone membrane that was subjected to tensile stretch. Measurements indicated cytoplasmic strains were similar to those of the underlying substrate, with a strain transfer ratio (STR) of 0.79. In contrast, nuclear strains were much smaller than those of the substrate, with an STR of 0.17. These findings are consistent with previous studies indicating nuclear stiffness is significantly greater than cytoplasmic stiffness, as measured using other methods. This study provides a novel method for the study of cellular mechanics, including a new technique for measuring intranuclear deformations, with evidence of differential magnitudes and patterns of strain transferred from the substrate to cell cytoplasm and nucleus.

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Cell delivery to the pathological intervertebral disc (IVD) has significant therapeutic potential for enhancing IVD regeneration. The development of injectable biomaterials that retain delivered cells, promote cell survival, and maintain or promote an NP cell phenotype in vivo remains a significant challenge. Previous studies have demonstrated NP cell - laminin interactions in the nucleus pulposus (NP) region of the IVD that promote cell attachment and biosynthesis. These findings suggest that incorporating laminin ligands into carriers for cell delivery may be beneficial for promoting NP cell survival and phenotype. Here, an injectable, laminin-111 functionalized poly(ethylene glycol) (PEG-LM111) hydrogel was developed as a biomaterial carrier for cell delivery to the IVD. We evaluated the mechanical properties of the PEG-LM111 hydrogel, and its ability to retain delivered cells in the IVD space. Gelation occurred in approximately 20 min without an initiator, with dynamic shear moduli in the range of 0.9-1.4 kPa. Primary NP cell retention in cultured IVD explants was significantly higher over 14 days when cells were delivered within a PEG-LM111 carrier, as compared to cells in liquid suspension. Together, these results suggest this injectable laminin-functionalized biomaterial may be an easy to use carrier for delivering cells to the IVD.

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Intervertebral disc herniation may contribute to inflammatory processes that associate with radicular pain and motor deficits. Molecular changes at the affected dorsal root ganglion (DRG), spinal cord, and even midbrain, have been documented in rat models of radiculopathy or nerve injury. The objective of this study was to evaluate gait and the expression of key pain receptors in the midbrain in a rodent model of radiculopathy. Radiculopathy was induced by harvesting tail nucleus pulposus (NP) and placing upon the right L5 DRG in rats (NP-treated, n=12). Tail NP was discarded in sham-operated animals (n=12). Mechanical allodynia, weight-bearing, and gait were evaluated in all animals over time. At 1 and 4 weeks after surgery, astrocyte and microglial activation was tested in DRG sections. Midbrain sections were similarly evaluated for immunoreactivity to serotonin (5HT(2B)), mu-opioid (µ-OR), and metabotropic glutamate (mGluR4 and 5) receptor antibodies. NP-treated animals placed less weight on the affected limb 1 week after surgery and experienced mechanical hypersensitivity over the duration of the study. Astroctye activation was observed at DRGs only at 4 weeks after surgery. Findings for pain receptors in the midbrain of NP-treated rats included an increased expression of 5HT(2B) at 1, but not 4 weeks; increased expression of µ-OR and mGluR5 at 1 and 4 weeks (periaqueductal gray region only); and no changes in expression of mGluR4 at any point in this study. These observations provide support for the hypothesis that the midbrain responds to DRG injury with a transient change in receptors regulating pain responses.

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Regular landscape patterning arises from spatially-dependent feedbacks, and can undergo catastrophic loss in response to changing landscape drivers. The central Everglades (Florida, USA) historically exhibited regular, linear, flow-parallel orientation of high-elevation sawgrass ridges and low-elevation sloughs that has degraded due to hydrologic modification. In this study, we use a meta-ecosystem approach to model a mechanism for the establishment, persistence, and loss of this landscape. The discharge competence (or self-organizing canal) hypothesis assumes non-linear relationships between peat accretion and water depth, and describes flow-dependent feedbacks of microtopography on water depth. Closed-form model solutions demonstrate that 1) this mechanism can produce spontaneous divergence of local elevation; 2) divergent and homogenous states can exhibit global bi-stability; and 3) feedbacks that produce divergence act anisotropically. Thus, discharge competence and non-linear peat accretion dynamics may explain the establishment, persistence, and loss of landscape pattern, even in the absence of other spatial feedbacks. Our model provides specific, testable predictions that may allow discrimination between the self-organizing canal hypotheses and competing explanations. The potential for global bi-stability suggested by our model suggests that hydrologic restoration may not re-initiate spontaneous pattern establishment, particularly where distinct soil elevation modes have been lost. As a result, we recommend that management efforts should prioritize maintenance of historic hydroperiods in areas of conserved pattern over restoration of hydrologic regimes in degraded regions. This study illustrates the value of simple meta-ecosystem models for investigation of spatial processes.

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A large percentage of the population may be expected to experience painful symptoms or disability associated with intervertebral disc (IVD) degeneration - a condition characterized by diminished integrity of tissue components. Great interest exists in the use of autologous or allogeneic cells delivered to the degenerated IVD to promote matrix regeneration. Induced pluripotent stem cells (iPSCs), derived from a patient's own somatic cells, have demonstrated their capacity to differentiate into various cell types although their potential to differentiate into an IVD cell has not yet been demonstrated. The overall objective of this study was to assess the possibility of generating iPSC-derived nucleus pulposus (NP) cells in a mouse model, a cell population that is entirely derived from notochord. This study employed magnetic activated cell sorting (MACS) to isolate a CD24(+) iPSC subpopulation. Notochordal cell-related gene expression was analyzed in this CD24(+) cell fraction via real time RT-PCR. CD24(+) iPSCs were then cultured in a laminin-rich culture system for up to 28 days, and the mouse NP phenotype was assessed by immunostaining. This study also focused on producing a more conducive environment for NP differentiation of mouse iPSCs with addition of low oxygen tension and notochordal cell conditioned medium (NCCM) to the culture platform. iPSCs were evaluated for an ability to adopt an NP-like phenotype through a combination of immunostaining and biochemical assays. Results demonstrated that a CD24(+) fraction of mouse iPSCs could be retrieved and differentiated into a population that could synthesize matrix components similar to that in native NP. Likewise, the addition of a hypoxic environment and NCCM induced a similar phenotypic result. In conclusion, this study suggests that mouse iPSCs have the potential to differentiate into NP-like cells and suggests the possibility that they may be used as a novel cell source for cellular therapy in the IVD.

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It is essential in musical performance not only to convey the unique language of the composers but also to approach each composition from the perspective of its style. During the 20th century, diverse musical idioms co-existed, sometimes mixing or fusing, yet retaining recognizable characteristics and thereby remaining distinctive. This dissertation explores myriad examples from Late Romanticism/Post- Romanticism, Naturalism, Neo-Classicism, Nationalism and Impressionism composed during this unusually rich period. In order to explore a broad range of collaborative repertoire and to deepen my knowledge of the styles and performance practices relating to these pieces, I studied and performed the repertoire with pianist Eunae Baik–Kim, clarinetist Jihoon Chang, and singers Joshua Brown and Young Joo Lee. The first program featured Post-Romantic, Neo-Classic and Impressionist two-piano works composed by Debussy, Rachmaninoff, and Stravinsky. Each of the three composers used their own distinctive harmonies, rhythms, melodic inventions, pedaling and figurations. In all of the works, both piano parts were densely interwoven, having equal importance. Lied and operatic aria was the focus of the second recital. Brahms’ Vier Ernste Gesänge Op. 121, Ravel’s Don Quichotte a Dulcineé and Italian, French and German operatic arias were the examples of Post-Romanticism and Nationalism. The representative composers were Verdi, Massenet, Korngold, Leoncavallo, Ravel and Wagner. Despite the fact that all of the repertoire was written in traditional musical forms, the composers’ unique voices mark each work as belonging to a particular genre. The third recital focused on Post-Romantic and Impressionistic music written for clarinet and piano: the Première Rhapsodie by Debussy, the Sonata by Poulenc and Brahms’ Sonata in F minor Op. 120, No. 1. These works, although profoundly different in style, share elements of simplicity, clarity and elegance as well as technical virtuosity, articulation and profound musical depth. The three recitals which comprise this dissertation project were performed at the University of Maryland Gildenhorn Recital Hall on February 27, 2010, October 25, 2010, and January 31, 2011. The recitals were recorded on compact disc and are archived within the Digital Repository at the University of Maryland (DRUM).

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Robert Schumann (1810-1856) and Johannes Brahms (1833-1897), in some ways Robert Schumann's artistic descendant, are the most important and representative German piano composers during the Romantic period. Schumann was already a mature and established musician in 1853 when he first met the young Brahms and recognized his talents, an encounter that had a long-lasting affect on the lives and careers of both men. After Schumann’s mental breakdown and death, Brahms maintained his admiration of Schumann’s music and preserved an intimate relationship with Clara Schumann. In spite of the personal and musical closeness of the two men, Schumann’s music is stylistically distinct from that of Brahms. Brahms followed traditions from Baroque and Classical music, and avoided using images and expressive titles in his music. Brahms extraordinarily intermingled earlier musical forms with multicolored tones of German Romanticism. In contrast, Schumann saw himself as a radical composer devoted to personal emotionalism and spontaneity. He favored programmatic titles for his character pieces and extra-musical references in his music. While developing their own musical styles as German Romantic composers, Schumann and Brahms both utilized the piano as a resourceful tool for self-realization and compositional development. To investigate and compare the main characteristics of Schumann and Brahms’s piano music, I looked at three genres. First, in the category of the piano concerto, I chose two major Romantic works, Schumann’s A minor concerto and Brahms’s B-flat major concerto. Second, for the category of piano variations I included two sets by Brahms because the variation framework was such an important vehicle for him to express his musical thoughts. Schumann’s unique motivic approach to variation is displayed vividly in his character-piece cycle Carnaval. Third, the category of the character piece, perhaps the favorite medium of Romantic expression at the piano, is shown by Schumann’s Papillons and Brahms’s sets of pieces Op.118 and Op.119. This performance dissertation consists of three recitals performed in the Gildenhorn Recital Hall at the University of Maryland, College Park. These recitals are documented on compact disc recordings that are housed within the University of Maryland Library System.

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Musical exoticism is the evocation of a culture different from that of the composer. It occurs anytime a composer tries to conjure up the music of a country not his own. Although there have been studies of exoticism in the piano works of an individual composer, namely Debussy, there has not been a comprehensive study of musical exoticism in the piano literature as a whole. Upon chronological examination of the piano repertoire, general trends exhibiting exoticism become evident. The first general trend is the emergence of the Turkish style (alia turca) in the eighteenth century. Turkish style soon transmuted to the Hungarian-Gypsy style (all 'ongarese or style hongrois). [In Beethoven's Op. 129, it is alia ingharese.] Composers often alternated between the two styles even in the same composition. By the late nineteenth century, style hongrois was firmly entrenched in the musical language of Austro-German composers, as seen in the works of Brahms. In the nineteenth century, composers turned to the Middle East, North Africa and Spain for inspiration. In particular are several compositions emulating Spanish dance music, culminating in the Spanish works of Debussy and Ravel. The gamelans from Indonesia and objects from the Far East of Japan and China, brought by advances in trade and transportation, captivated the imagination of composers at the turn of the twentieth century. Also in the early twentieth century, composers tried emulating dance and jazz music coming from the Americas, such as the cakewalk, minstrelsy, and the blues. One sees the ever widening sphere of exotic inspiration for western music composers: from the Turkish invasions to the traveling Gypsies of Hungary; to the captivating dance rhythms, soulful cante jondo sections, and guitar flourishes of Spain; expanding further to the far reaches of Asia and the jazzy rhythms of the Americas. This performance dissertation consists of three recitals presented at the University of Maryland, and is documented on compact disc recordings which are housed within the University of Maryland Library System. The recordings present the music of Balakirev, Beethoven, Brahms, Chopin, Debussy, Haydn, Hummel, Milhaud, Moszkowski, Mozart, Ravel, and Schubert.

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Throughout the piano’s history, certain composers have created innovations in the areas of virtuosity and sonority. These innovations came not only from the composers’ imagination, but also from the development of instruments and changes in musical style from one period to another. To investigate what kinds of innovations these pianist composers made, I divided them into technique and sound from Mozart to Cowell. I chose two-piano music (Sonata in D major, K.448 by Mozart and Rachmaninoff’s Second Suite) to demonstrate their experiments with varieties of textures and sonorities, using different registers of the two pianos orchestrally. En Blanc et noir by Debussy shows this composer’s deep interest and originality in piano sonorities. For solo piano music, Beethoven’s Piano Sonata Op.53 shows extensive technical invention. His use of long pedal effects shows a pianistic possibility not explored by Mozart. Hummel’s Piano Sonata in D major represents orchestral devices as well as pianistic techniques showing recent developments in the instrument. Chopin’s Ballade No.3 and Scherzo No.3 show virtuosic moments and also the expanded range of the keyboard. His Nocturne Op.27, no.2, with its sonorities resulting from the combination of pedal, and widespread accompaniments derived from Alberti bass figures, is a perfect example of Chopin’s characteristic sound-world. “Vallée d’Obermann” by Liszt uses many virtuosic techniques as well as the extreme wide ranges of keyboard in both hands to create dramatic contrasts of texture. Debussy’s etude, “Pour les Sonorités opposés” is probably the first etude designed for sonority rather than for keyboard virtuosity. Albeniz’s “Evocación” and “Triana” show Spanish atmosphere. Prokofiev’s Sonata no.3 shows frequent motoric driving elements that demand percussive virtuosity. Cowell’s piano music is some of the earliest to explore the sonorities of tone clusters and playing on the strings. This performance dissertation consists of three recitals performed in the Orchestra Room, Leah Smith Hall, and Gildenhorn Recital Hall at the University of Maryland, College Park. These recitals are documented on compact disc recordings that are housed within the University of Maryland Library System.

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During the 19th century, Frédéric Chopin (1810-1849), Franz Liszt (1811- 1886), and Johannes Brahms (1833-1897) were among the most recognized composers of character pieces. Their compositions have been considered a significant milestone in piano literature. Frédéric Chopin (1810-1849) did not give descriptive titles to his character pieces. He grouped them into several genres such as Mazurkas, Polonaises. His Mazurkas and Polonaises are influenced by Polish dance music and inspired by the polish national idiom. Franz Liszt (1811-1886) was influenced in many ways by Chopin, and adopted Chopin’s lyricism, melodic style, and tempo rubato. However, Liszt frequently drew on non-musical subjects (e.g., art, literature) for inspiration. “Harmonies poétiques et religieuses” and “Années de pèlerinage” are especially representative of character pieces in which poetic and pictorial imagination are reflected. Johannes Brahms (1833-1897) was a conservative traditionalist, synthesizing Romantic expression and Classical tradition remarkably well. Like Chopin, Brahms avoided using programmatic titles for his works. The titles of Brahms’ short character pieces are often taken from traditional lyrical or dramatic genres such as ballade, rhapsody and scherzo. Because of his conservatism, Brahms was considered the main rival of Liszt in the Romantic Period. Brahms character pieces in his third period (e.g., Scherzo Op.4, Ballades of Op.10, and Rhapsodies of Op.79) are concise and focused. The form of Brahms’ character pieces is mostly simple ternary (ABA), and his style is introspective and lyrical. Through this recording project, I was able to get a better understanding of the styles of Chopin, Brahms and Liszt through their character pieces. This recording dissertation consists of two CDs recorded in the Dekelboum Concert Hall at the University of Maryland, College Park. These recordings are documented on compact disc recordings that are housed within the University of Maryland Library System.

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This dissertation explores the transformation of opera comique (as represented by the opera Carmen) and the impact of verismo style (as represented by the opera La Boheme) upon the development of operetta, American musical theater and the resultant change in vocal style. Late nineteenth-century operetta called for a classically trained soprano voice with a clear vibrato. High tessitura and legato were expected although the quality of the voice was usually lighter in timbre. The dissertation comprises four programs that explore the transformation of vocal and compositional style into the current vocal performance practice of American musical theater. The first two programs are operatic roles and the last two are recital presentations of nineteenth- and twentieth- century operetta and musical theater repertoire. Program one, Carmen, was presented on July 26, 2007 at the Marshall Performing Arts Center in Duluth, MN where I sang the role of Micaela. Program two, La Boheme, was presented on May 24,2008 at Randolph Road Theater in Silver Spring, MD where I sang the role of Musetta. Program three, presented on December 2, 2008 and program four, presented on May 10, 2009 were two recitals featuring operetta and musical theater repertoire. These programs were heard in the Gildenhorn Recital Hall at the Clarice Smith Performing Arts Center in College Park, MD. Programs one and two are documented in a digital video format available on digital video disc. Programs three and four are documented in a digital audio format available on compact disc. All programs are accompanied by program notes also available in digital format.

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This Dissertation Project comprises recordings of Argentine art songs. The discs are approximately 40-60 minutes in length and consist of songs from the traditional art-song repertoire for voice and piano. This project is particularly appropriate because of the very limited number of recordings of Argentine songs, which are notable both not only for their high quality but for their accessibility of performance for voice teachers, students, and professional singers alike. Art songs in the Spanish language are a welcome resource, and the poetry included in this project is of an outstanding quality. Some of the poets set to music are Gabriela Mistral (a poet laureate of Chile and the first Latin American woman to win the Nobel Prize for Literature), Pablo Neruda (also a Nobel laureate), Luis Cernuda, and Leon Benar6s. The lyrics of some songs are based on traditional sources, and the melodies and rhythms of all are representative of South American-indigenous and European­ immigrant cultures. The composers represented here will be familiar to some listeners but more than likely unfamiliar to most. Yet Alberto Ginastera (1916-1983) is considered to be the greatest of all Argentine composers. Alberto Williams (1862-1952) is known as the father of the Nationalist School of composition in Argentina, and Carlos Lopez Buchardo (1881-1963) is a most influential composer and pedagogue after whom the national Conservatory of Music in Buenos Aries is named. Two composers who remain relatively unknown outside of South America, Abraham Jurafsky (1906- 1993) and Julio Perceval (1903-1963) are also represented in this project. A complete compact disc is devoted to the works of Carlos Guastavino. Known as the "Argentine Schubert", Guastavino has over 250 songs to his credit. Chiefly a composer for piano and voice, his recent death (October 2000) makes a recording of his works especially appropriate. This project also includes a written component, a supportive dissertation briefly describing the history of the Argentine art song and the lives and influences of the composers and poets represented in the studio recordings. The CD recordings are held in the Michelle Smith Performing Arts Library at the University of Maryland.

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The zinc-finger protein Rotund (Rn) plays a critical role in controlling the development of the fly olfactory system. However, little is known about its molecular function in vivo. Here, we added protein tags to the rn locus using CRISPR-Cas9 technology in Drosophila to investigate its subcellular localization and the genes that it regulates . We previously used a reporter construct to show that rn is expressed in a subset of olfactory receptor neuron (ORN) precursors and it is required for the diversification of ORN fates. Here, we show that tagged endogenous Rn protein is functional based on the analysis of ORN phenotypes. Using this method, we also mapped the expression pattern of the endogenous isoform-specific tags in vivo with increased precision. Comparison of the Rn expression pattern from this study with previously published results using GAL4 reporters showed that Rn is mainly present in early steps in antennal disc patterning, but not in pupal stages when ORNs are born. Finally, using chromatin immunoprecipitation, we showed a direct binding of Rotund to a previously identified regulatory element upstream of the bric-a-brac gene locus in the developing antennal disc.

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The Fantasy, as the term suggests, is a genre that composers have found congenial for exploring innovative and imaginative processes. Works in this genre are numerous in the solo piano literature, and extend even to works for piano and orchestra and to chamber music with piano. I was curious to explore how a specific genre of music maintained similar characteristics but evolved over time. A fantasy is primed to be inventive and I wanted to see how composers from different eras and backgrounds would handle their material in this genre. I have learned that composers worked through formal developments while making innovations within this genre. The heart of my dissertation is presented through the recording project. Because ofthe abundance ofpiano fantasies, many works had to be excluded from this project for time's sake. On two compact discs, I have recorded approximately two hours of solo piano music. I have included some shorter fantasies to magnify significant developments from era to era, country to country, and composer to composer. The first disc has recordings of eighteenth and nineteenth-century fantasies: Chromatic Fantasy and Fugue, BWV 903 by J.S. Bach (1685-1750); Fantasia inC major, H. XVII, 4 by Franz Joseph Haydn (1732-1809); Fantasy inc minor, K. 475 by Wolfgang Amadeus Mozart (1756- 1791); Fantasia inf-sharp minor, Op. 28 by Felix Mendelssohn (1809-1847); and Polonaise-Fantaisie in A-flat major, Op. 61 by Frederic Chopin (1810-1849). On the second disc I have included mid-19th, 20th and 2151-century piano fantasies: Fantasy and Fugue on the Theme B-A-C-H by Franz Liszt (1811-1886); Fantasia Baetica by Manuel de Falla (1876-1946); Three Fantasies by William Bergsma (1921-1994); Fantasy, Aria and Fugue by Frederic Goossen (1927-2011); and Piano Fantasy ("Wenn ich einmal sol! scheiden") by Richard Danielpour (b. 1956). The accompanying document includes program notes for each of the pieces recorded. They were recorded on a Steinway "D" in Dekelboum Concert Hall at the University of Maryland by Antonino D'Urzo ofOpusrite Productions. This document is available in the Digital Repository at the University of Maryland and the CO's are available through the Library System at the University of Maryland.