113 research outputs found
Collagen Scaffolds Incorporating Select Therapeutic Agents to Facilitate a Reparative Response in a Standardized Hemiresection Defect in the Rat Spinal Cord
No full textA multifaceted therapeutic approach involving biomaterial scaffolds, neurotrophic factors, exogenous cells, and antagonists to axon growth inhibitors may ultimately prove necessary for the treatment of defects resulting from spinal cord injury (SCI). The objective of this study was to begin to lay the groundwork for such strategies by implanting type I collagen scaffolds alone and incorporating individually a soluble Nogo receptor, chondroitinase ABC (ChABC), and mesenchymal stem cells (MSCs) into a standardized 3-mm-long hemiresection defect in the rat spinal cord. Statistically significant improvement in hindlimb motor function between the first and fourth weeks post-SCI was recorded for the scaffold-alone group and for the ChABC and MSC groups, but not the control group. Four weeks post-SCI, the scaffolds appeared intact with open pores, which were infiltrated with host cells. Of note is that in some cases, a few growth-associated protein 43 (GAP-43)-positive axons were seen reaching the center of the scaffold in the scaffold-alone and ChABC groups, but not in control animals. Angiogenic cells were prevalent in the scaffolds; however, the number of both macrophages and angiogenic cells in the scaffolds was significantly less than in the control lesion at 4 weeks. The results lay the foundation for future dose–response studies and to further investigate a range of therapeutic agents to enhance the regenerative response in SCI.Gates Millennium Scholars Program (Fellowship
Bio-inspired organized structures guiding nerve regeneration
No full textAutologous nerve grafting is the current gold standard treatment for peripheral nerve injury, in cases where direct suturing of nerve ends is not possible. Even though the functional restoration achieved by the autograft is not optimal, autologous nerve tissues still show higher regenerative capability than several synthetic conduits available in the clinical setting, the latter used only for gaps that do not exceed 3 cm in length. The aim of this chapter is to highlight how bio-mimicry, inspired by nerve development, structure and spontaneous regeneration following mild nerve injury, can help in the design of synthetic templates with optimized bioactivity for nerve regeneration
Impact of different sterilization methods on the structure, biodegradation and cell response of collagen scaffolds designed for peripheral nerve regeneration
No full textSterilization of collagen scaffolds designed for peripheral nerve regeneration: Effect on microstructure, degradation and cellular colonization
No full textIn this study we investigated the impact of three different sterilization methods, dry heat (DHS), ethylene oxide (EtO) and electron beam radiation (β), on the properties of cylindrical collagen scaffolds with longitudinally oriented pore channels, specifically designed for peripheral nerve regeneration. Scanning electron microscopy, mechanical testing, quantification of primary amines, differential scanning calorimetry and enzymatic degradation were performed to analyze possible structural and chemical changes induced by the sterilization. Moreover, in vitro proliferation and infiltration of the rat Schwann cell line RSC96 within the scaffolds was evaluated, up to 10 days of culture. No major differences in morphology and compressive stiffness were observed among scaffolds sterilized by the different methods, as all samples showed approximately the same structure and stiffness as the unsterilized control. Proliferation, infiltration, distribution and morphology of RSC96 cells within the scaffolds were also comparable throughout the duration of the cell culture study, regardless of the sterilization treatment. However, we found a slight increase of chemical crosslinking upon sterilization (EtO < DHS < β), together with an enhanced resistance to denaturation of the EtO treated scaffolds and a significantly accelerated enzymatic degradation of the β sterilized scaffolds. The results demonstrated that β irradiation impaired the scaffold properties to a greater extent, whereas EtO exposure appeared as the most suitable method for the sterilization of the proposed scaffolds
Studio della microporosità di scaffold in collagene per la rigenerazione del midollo spinale
No full textLe lesioni del midollo spinale nell’uomo sono molto eterogenee. L’incapacità di rigenerazione del midollo lesionato è attribuita all’instaurarsi di un ambiente inibitorio e alla formazione di una cicatrice gliale che funge da barriera chimica e meccanica alla rigenerazione assonale. L’impianto di scaffold microporosi rappresenta una valida strategia per guidare la rigenerazione, nel tentativo di ripristinare i collegamenti con i target di innervazione e promuovere il recupero funzionale. Porosità, distribuzione delle dimensioni dei pori, area superficiale specifica, interconnettività ed orientazione dei pori sono parametri cruciali che influenzano la bioattività dello scaffold. Lo scopo del presente lavoro è quello di modulare e caratterizzare la struttura microporosa di scaffold cilindrici in collagene, con porosità orientata in direzione longitudinale o assiale, destinati ad uno studio sulla rigenerazione del midollo spinale. Gli scaffold (3mm diametro, 3 cm lunghezza) sono stati realizzati mediante freezing unidirezionale di sospensioni di collagene di tipo I da derma bovino (a diverse concentrazioni), liofilizzazione e reticolazione termica e chimica. La porosità degli scaffold è stata quindi analizzata qualitativamente e quantitativamente mediante microscopia elettronica a scansione e ottica, al fine di determinare morfologia, omogeneità, diametro medio e grado di orientazione dei pori. L’analisi delle sezioni trasversali e longitudinali degli scaffold ha mostrato rispettivamente una distribuzione pressoché omogenea e una buona orientazione uniassiale dei pori per tutte le tipologie di campioni analizzate, evidenziando una leggera diminuzione della dimensione media all’aumentare della concentrazione di collagene utilizzata in fase di sintesi. Tuttavia, si è anche osservato un gradiente crescente del diametro medio dei pori lungo l’asse longitudinale degli scaffold, legato al gradiente di temperatura che si instaura durante il processo di freezing uniassiale. Inoltre, i trattamenti di reticolazione investigati sembrano non influenzare significativamente la microstruttura. Studi futuri saranno rivolti a comprendere l’effetto della microstruttura sul comportamento di cellule neuronali, immortalizzate e primarie, in vitro
Scaffolds for bone regeneration made of hydroxyapatite microspheres in a collagen matrix
No full textBiomimetic scaffolds with a structural and chemical composition similar to native bone tissue may be promising for bone tissue regeneration. In the present work hydroxyapatite mesoporous microspheres (mHA) were incorporated into collagen scaffolds containing an ordered interconnected macroporosity. The mHA were obtained by spray drying of a nano hydroxyapatite slurry prepared by the precipitation technique. X-ray diffraction (XRD) analysis revealed that the microspheres were composed only of hydroxyapatite (HA) phase, and energy-dispersive x-ray spectroscopy (EDS) analysis revealed the Ca/P ratio to be 1.69 which is near the value for pure HA. The obtained microspheres had an average diameter of 6 μm, a specific surface area of 40 m(2)/g as measured by Brunauer-Emmett-Teller (BET) analysis, and Barrett-Joyner-Halenda (BJH) analysis showed a mesoporous structure with an average pore diameter of 16 nm. Collagen/HA-microsphere (Col/mHA) composite scaffolds were prepared by freeze-drying followed by dehydrothermal crosslinking. SEM observations of Col/mHA scaffolds revealed HA microspheres embedded within a porous collagen matrix with a pore size ranging from a few microns up to 200 μm, which was also confirmed by histological staining of sections of paraffin embedded scaffolds. The compressive modulus of the composite scaffold at low and high strain values was 1.7 and 2.8 times, respectively, that of pure collagen scaffolds. Cell proliferation measured by the MTT assay showed more than a 3-fold increase in cell number within the scaffolds after 15 days of culture for both pure collagen scaffolds and Col/mHA composite scaffolds. Attractive properties of this composite scaffold include the potential to load the microspheres for drug delivery and the controllability of the pore structure at various length scales
Collagen implants to promote regeneration of the adult rat spinal cord
No full textThesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 50-52).Over 250,000 people in the United States currently live with a spinal cord injury and approximately 11,000 new cases occur every year. People with spinal cord injuries experience a significant reduction in quality of life due to the many problems that arise from damage to the spinal cord including paralysis and loss of sensation below the location of injury, loss of bowel and bladder function, loss of sexual function, and impaired respiration. Despite considerable ongoing research in the area of nerve regeneration by various institutions, satisfactory treatment for spinal cord injury has not yet been discovered. Previous studies have had considerable success in facilitating the regeneration of severed peripheral nerves through the use of collagen based implants used to bridge the resulting gap between the severed nerve stumps. The current study aims to apply this same regenerative approach to a defect created in the spinal cord of adult rats. The objective is to evaluate the efficacy of three different collagen implants toward the regeneration of the spinal cord. The experimental spinal cord injury was a complete transection at T7 and T9 and the removal of the spinal cord segment between the two transections, creating a 5 mm gap.(cont.) This study contained four experimental groups. Group I was the control group. The animals in this group had a complete spinal cord transection as described above but received no implantation. Group II received a resorbable dura replacement sheet of collagen, 1 mm thick, cut from the BioGide(® membrane which was placed extradurally over the dorsal aspect of the wound site. Group III used the BioGide® membrane as a wrap which bridged the gap between the two cord stumps. Group IV used a collagen tube, fabricated using a freeze-drying process, to bridge the gap. Histological analysis at 6 weeks after implantation showed Groups III and IV to have more longitudinally oriented reparative tissue filling the defect area as well as fewer fluid-filled cysts. Quantitative analysis of axonal regeneration showed the collagen implants to be supportive of the regeneration of axons into the center of the defect.by Rahmatullah H. Cholas.S.M
Collagen scaffolds in full- and hemi- resection spinal cord injury models
No full textThesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 110-117).Basic scientific research over the past few decades has shown some light on the complex pathophysiology of SCI and has enhanced our understanding of some of the important factors that contribute to the lack of regeneration following the initial traumatic injury and secondary injury response in the adult spinal cord. These factors include both intrinsic limitations in the regeneration capacity of mature neurons, but also a host of environmental factors which inhibit spontaneous attempts of axon regeneration. These environmental factors include physical barriers to axon regeneration such as fibrous and glial scars as well as molecules which actively inhibit regeneration. Even when these barriers are removed, axons in the central nervous system still require the appropriate stimulatory signals in order for significant regeneration to occur. These signals may include a substrate to provide directional guidance of the extending axon growth cones as well as neurotrophic factors to promote axon growth and survival. Thus, to achieve a clinically meaningful regenerative response following spinal cord injury a combinatorial therapeutic approach is likely necessary. This thesis investigated the use of a porous collagen scaffold with aligned pores to serve as a substrate for axon guidance and a delivery vehicle for select therapeutic agents in both fulland hemi- resection injury models in adult rats. In the hemi-resection injury model, the treatment groups included: a dehydrothermally (DHT) crosslinked scaffold, a carbodiimide (EDAC) crosslinked scaffold, and an EDAC-treated scaffold delivering either soluble Nogo receptor (sNgR), chondroitinase ABC (ChABC), or bone marrow derived mesenchymal stem cells (MSCs). Improvement in hindlimb function over four weeks following injury was seen in the DHT scaffold, EDAC scaffold + ChABC, and EDAC scaffold + MSCs groups, but not in the untreated control group. Immunohistochemical evaluation of the tissue revealed a few regenerating axons reaching the center of the scaffold in the DHT scaffold and EDAC scaffold + ChABC groups at 4 week post injury. Histological evaluation at 4 weeks showed the defect area of all groups to be largely comprised of loosely organized fibrous tissue. Many macrophages were seen surrounding the defect area of all groups; however, there were significantly more macrophages within the defect area of the control group compared to the treatment groups. In the full-resection injury model, at 6 weeks post injury, implanted collagen scaffolds tended to reduce the number of cystic cavities in the defect and to better align the reparative tissue with the long axis of the spinal cord. These results show the potential benefit of collagen scaffolds alone or in combination with select therapeutic agents as a means to modulate the healing response following spinal cord injury.by Rahmatullah H. Cholas.Ph.D
Analisis Penerapan Akuntansi Pada Badan Usaha Milik Desa (bumdes) Saiyo Lumindai Desa Lumindai Kecamatan Barangin Kota Sawahlunto Oleh: Natasya Rahmatullah 205310154 Program Studi Akuntansi Fakultas Ekonomi Dan Bisnis Universitas Islam Riau Pekanbaru 2024
No full textThis study aims to assess the suitability of the implementastion of generally accepted accounting at the Badan Usaha Milik Desa (BUMDes) Saiyo Lumindai, Lumindai Village, Barangin District, Sawahlunto City. The method used by the author is qualitative descriptive method so that this study is able to produce a description or explanation in depth of the facts encountered in the field, then connect it with the theorities that the author has obtained, so that a conclusion can be drawn which is a solution to the problem faced. The data used in this study consists of primary data and secondary data. Data collection techniques use direct interview and documentation. Based on the results of the research conducted by the author, it can be concluded that the accounting process at BUMDes Saiyo Lumindai, Lumindai Village, Barangin District, Sawahlunto City, in the recording process uses accrual basis method. BUMDes Saiyo Lumindai does not present complete financial reports and only makes financial reports in the form of financial posisition and profit and loss statement. So it can be concluded that the application of accounting at BUMDes Saiyo Lumindai is not in accordance with generally accepted accounting principles
FACTORS AFFECTING STUDENTS’ DIFFICULTIES IN SPEAKING AT UIN SAYYID ALI RAHMATULLAH TULUNGAGUNG
No full textNabawi, Moch Zuan. Student Registered Number. 12203183272. 2022. Factors
Affecting Students' Difficulties in Speaking at UIN Sayyid Ali Rahmatullah
Tulungagung. Sarjana Thesis. English Education Department. Faculty of
Tarbiyah and Teacher Training. Advisor: Dr. Nurul Chojimah, M.Pd.
Keyword: Speaking, Speaking problem
Speaking is the process of expressing ideas, opinions, and thoughts in spoken
language. More specifically, speaking can be used as a medium to communicate
by expressing ideas through words and speaking is one of the most important
aspects of language learning. Next is when speaking activities in class, there will
definitely be some problems. Speaking problems can hinder students when
speaking English. The author hopes that readers can understand the definition of
speaking and the factors in speaking problems and the solutions to overcome
them.
The aims of this study are: (1) To know what factors that contribute to the
students’ difficulties in speaking at the UIN Sayyid Ali Rahmatullah
Tulungagung. (2) To know how the students minimize the difficulties in speaking
at the UIN Sayyid Ali Rahmatullah Tulungagung.
The method in this research is qualitative research. The data obtained from
observation and interview. Observation were used to obtain data to answer the
problem formulation about internal and external factors that can affect students'
difficulties in speaking English, while interview were used to obtain more indepth data than answering questions.
The results showed that there are two factors that influence students'
difficulties when speaking English, namely internal factors and external factors.
Internal factors come from within oneself and external factors come from outside.
Internal factors consist of performance condition, anxiety, motivation and
listening ability, while external factors consist of learning environment. The
learning environment is divided into four points, namely mother tongue, learning
groups (support from friends), support from family and relatives and campus
facilities. The solution to overcome these factors is to understand the purpose of
learning English, force yourself to practice in a creative and consistent way,
master and prepare the material well and use campus facilities wisely
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