90 research outputs found
Aerospace medicine and biology: A cumulative index to a continuing bibliography (supplement 358)
This publication is a cumulative index to the abstracts contained in Supplements 346 through 357 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes: subject, personal author, corporate source, foreign technology, contract number, report number and accession number
Data Acquisition Applications
Data acquisition systems have numerous applications. This book has a total of 13 chapters and is divided into three sections: Industrial applications, Medical applications and Scientific experiments. The chapters are written by experts from around the world, while the targeted audience for this book includes professionals who are designers or researchers in the field of data acquisition systems. Faculty members and graduate students could also benefit from the book
NASA Tech Briefs, January 1993
Topics include: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences
A Pattern-Based Approach for Detecting Pneumatic Failures on Temporary Immersion Bioreactors
Temporary Immersion Bioreactors (TIBs) are used for increasing plant quality and plant multiplication rates. These TIBs are actioned by mean of a pneumatic system. A failure in the pneumatic system could produce severe damages into the TIB. Consequently, the whole biological process would be aborted, increasing the production cost. Therefore, an important task is to detect failures on a temporary immersion bioreactor system. In this paper, we propose to approach this task using a contrast pattern based classifier. We show that our proposal, for detecting pneumatic failures in a TIB, outperforms other approaches reported in the literature. In addition, we introduce a feature representation based on the differences among feature values. Additionally, we collected a new pineapple micropropagation database for detecting four new types of pneumatic failures on TIBs. Finally, we provide an analysis of our experimental results together with experts in both biotechnology and pneumatic devices
Engineering osteochondral tissues with human adipose tissue derived stem cells under precise biomechanical and biochemical in vitro environments
Tese de doutoramento em Engenharia BiomédicaWith the continuous increase in life expectancy, health problems tend to arise, whereas joint
ailments are among the most prevalent. The knee joint, in particular, is subjected to serious
illnesses that range from articular cartilage injuries, osteochondral lesions and osteoarthritis.
Joint pathologies globally affect population of all ages and gender, resulting in reduced quality
of life due to limited activity and increased expenditures, either directly (treatment, private
expenditure), or indirectly (lost productivity, lost earnings). In this context, the need for new
therapies and products that could satisfy the growing clinical requirements will rise in the future.
Tissue engineering and regenerative medicine, as a rapidly emerging field, is expected to
provide valuable solutions.
Osteochondral lesions are articular cartilage lesions where the underlying bone is also
damaged. A tissue engineering approach needs to address the cartilage component,
composed by a hydrated soft tissue layer, and the bone compartment, composed by a stiff,
complex and vascularized tissue.
In this thesis we propose complementary approaches to evolve current state of the art, and
move a step further in the development of functional solutions for cartilage, bone and/or
osteochondral regeneration. Our rationale was based on the use of human adipose stem cells
(hASC) as a single cell source to engineer all tissue compartments, by taking advantage of its
characteristics: 1) hASC have intrinsic capacity to differentiate into the chondrogenic,
osteogenic and endothelial lineages; 2) hASC can be obtained from adipose tissue collected by
dedicated or non-dedicated liposuction procedures, repeatedly and abundantly; 3) hASC are
isolated by enzymatic digestion, yielding high cell number, which may avoid or minimize cell
expansion. Furthermore, we explored the use of precise biomechanical and biochemical
environments specific for each engineered tissue, in order to improve cell differentiation and
matrix deposition. Specifically, hydrostatic pressure stimulation was employed for cartilage
engineering, while flow perfusion and inherent shear stress were investigated in bone
development context. In order to vascularize engineered bone, a specific spatio-temporal
regulation of growth factors and cells were thoroughly explored. To this end, five experimental studies were performed. The first studied focused on the
development of two bioreactor devices aimed at generating hydrostatic pressure (HP) for
dynamic culturing of cartilage tissue. We hypothesized that the formation of engineered
cartilage could be augmented by applying such physiologic stimuli to chondrogenic cells
(human nasal chondrocytes - HNC) or stem cells (human adipose stem cells - hASC), cultured
in gellan gum hydrogels, by varying both frequency and magnitude of loading. In the HNC
study, the best tissue development was achieved for pulsatile HP regimen, while in the hASC
study, the best cartilage outcomes were obtained for physiologic loading (5 MPa), as
evidenced by gene expression of aggrecan, collagen type II and sox-9, metachromatic staining
of cartilage matrix and immunolocalization of collagens.
The next step aimed to evaluate the effects of scaffold architecture and biomechanics, in order
to optimize silk scaffolds for bone tissue engineering. Silk scaffolds were fabricated using
different solvents (aqueous vs. hexafluoro-2-propanol - HFIP), pore sizes (250-500μm vs. 500-
1000μm) and structures (lamellar vs. spherical pores). Given the great potential of hASC for
cell-based therapies and tissue engineering, in particular bone tissue, silk scaffold and hASCs
are two promising components, which have not been previously investigated in combination.
The porous HFIP silk scaffold with 400-600 μm pores performed better than any other scaffold,
while the lamellar scaffolds performed better than spherical-pore scaffolds.
We further used this HFIP-silk scaffold as cell support for dynamic culturing studies, where the
effects of pulsatile perfusion on in vitro bone expression by human adipose stem cells (hASCs)
was assessed. We hypothesized that the formation of engineered bone could be augmented by
replicating physiologic stimuli – pulsatile interstitial flow - to cells cultured in porous scaffolds
using bioreactors with medium perfusion. This was confirmed, once the best tissue
development was achieved for the sequence of 2 weeks of steady flow and 3 weeks of
pulsatile flow, as evidenced by gene expression, construct compositions, histomorphologies
and biomechanical properties.
Further challenge was to vascularize the engineered bone grafts. Even more demanding was
to use the same cell source – hASC. From a clinical perspective, it would be ideal to engineer
vascularized bone grafts starting from one single cell harvest obtained from the patient. We
hypothesized that a sequential application of osteogenic and endothelial growth factors to
hASC cultured on biomaterial scaffolds (HFIP-silk scaffold), with different timing of addition of
fresh cells could support the development of bone-like tissue containing an integrated vascular To this end, five experimental studies were performed. The first studied focused on the
development of two bioreactor devices aimed at generating hydrostatic pressure (HP) for
dynamic culturing of cartilage tissue. We hypothesized that the formation of engineered
cartilage could be augmented by applying such physiologic stimuli to chondrogenic cells
(human nasal chondrocytes - HNC) or stem cells (human adipose stem cells - hASC), cultured
in gellan gum hydrogels, by varying both frequency and magnitude of loading. In the HNC
study, the best tissue development was achieved for pulsatile HP regimen, while in the hASC
study, the best cartilage outcomes were obtained for physiologic loading (5 MPa), as
evidenced by gene expression of aggrecan, collagen type II and sox-9, metachromatic staining
of cartilage matrix and immunolocalization of collagens.
The next step aimed to evaluate the effects of scaffold architecture and biomechanics, in order
to optimize silk scaffolds for bone tissue engineering. Silk scaffolds were fabricated using
different solvents (aqueous vs. hexafluoro-2-propanol - HFIP), pore sizes (250-500μm vs. 500-
1000μm) and structures (lamellar vs. spherical pores). Given the great potential of hASC for
cell-based therapies and tissue engineering, in particular bone tissue, silk scaffold and hASCs
are two promising components, which have not been previously investigated in combination.
The porous HFIP silk scaffold with 400-600 μm pores performed better than any other scaffold,
while the lamellar scaffolds performed better than spherical-pore scaffolds.
We further used this HFIP-silk scaffold as cell support for dynamic culturing studies, where the
effects of pulsatile perfusion on in vitro bone expression by human adipose stem cells (hASCs)
was assessed. We hypothesized that the formation of engineered bone could be augmented by
replicating physiologic stimuli – pulsatile interstitial flow - to cells cultured in porous scaffolds
using bioreactors with medium perfusion. This was confirmed, once the best tissue
development was achieved for the sequence of 2 weeks of steady flow and 3 weeks of
pulsatile flow, as evidenced by gene expression, construct compositions, histomorphologies
and biomechanical properties.
Further challenge was to vascularize the engineered bone grafts. Even more demanding was
to use the same cell source – hASC. From a clinical perspective, it would be ideal to engineer
vascularized bone grafts starting from one single cell harvest obtained from the patient. We
hypothesized that a sequential application of osteogenic and endothelial growth factors to
hASC cultured on biomaterial scaffolds (HFIP-silk scaffold), with different timing of addition of
fresh cells could support the development of bone-like tissue containing an integrated vascularTo this end, five experimental studies were performed. The first studied focused on the
development of two bioreactor devices aimed at generating hydrostatic pressure (HP) for
dynamic culturing of cartilage tissue. We hypothesized that the formation of engineered
cartilage could be augmented by applying such physiologic stimuli to chondrogenic cells
(human nasal chondrocytes - HNC) or stem cells (human adipose stem cells - hASC), cultured
in gellan gum hydrogels, by varying both frequency and magnitude of loading. In the HNC
study, the best tissue development was achieved for pulsatile HP regimen, while in the hASC
study, the best cartilage outcomes were obtained for physiologic loading (5 MPa), as
evidenced by gene expression of aggrecan, collagen type II and sox-9, metachromatic staining
of cartilage matrix and immunolocalization of collagens.
The next step aimed to evaluate the effects of scaffold architecture and biomechanics, in order
to optimize silk scaffolds for bone tissue engineering. Silk scaffolds were fabricated using
different solvents (aqueous vs. hexafluoro-2-propanol - HFIP), pore sizes (250-500μm vs. 500-
1000μm) and structures (lamellar vs. spherical pores). Given the great potential of hASC for
cell-based therapies and tissue engineering, in particular bone tissue, silk scaffold and hASCs
are two promising components, which have not been previously investigated in combination.
The porous HFIP silk scaffold with 400-600 μm pores performed better than any other scaffold,
while the lamellar scaffolds performed better than spherical-pore scaffolds.
We further used this HFIP-silk scaffold as cell support for dynamic culturing studies, where the
effects of pulsatile perfusion on in vitro bone expression by human adipose stem cells (hASCs)
was assessed. We hypothesized that the formation of engineered bone could be augmented by
replicating physiologic stimuli – pulsatile interstitial flow - to cells cultured in porous scaffolds
using bioreactors with medium perfusion. This was confirmed, once the best tissue
development was achieved for the sequence of 2 weeks of steady flow and 3 weeks of
pulsatile flow, as evidenced by gene expression, construct compositions, histomorphologies
and biomechanical properties.
Further challenge was to vascularize the engineered bone grafts. Even more demanding was
to use the same cell source – hASC. From a clinical perspective, it would be ideal to engineer
vascularized bone grafts starting from one single cell harvest obtained from the patient. We
hypothesized that a sequential application of osteogenic and endothelial growth factors to
hASC cultured on biomaterial scaffolds (HFIP-silk scaffold), with different timing of addition of
fresh cells could support the development of bone-like tissue containing an integrated vascular network. Three strategies were evaluated by changing spatio-temporal cues, but only one of
the combinations, in particular the osteo-induction of hASC seeded to silk scaffold for 3 weeks,
followed by addition of fibrin-encapsulated hASC to which vasculogenic cues were provided for
2 weeks, resulted in the most promising outcomes towards vascularized bone grafts.
The final experimental design focused on the development of an in vitro model for studies of
heterotypic cellular interactions that couple blood vessel formation with osteogenesis by using
human umbilical vein endothelial cells (HUVECs) and human bone marrow mesenchymal stem
cells (hMSCs). In this study, we hypothesized that the sequential application of growth factors,
to firstly induce the formation of stable vasculature and subsequently initiate osteogenic
differentiation, could provide a biologically-inspired in vitro model of bone vascularization. Two
important findings resulted from these studies: (i) vascular development needs to be induced
prior to osteogenesis, and (ii) the addition of additional hMSCs at the osteogenic induction
stage improves both tissue outcomes, and anastomosis of vascular networks with the host
(SCID mice) vasculature.
Taken altogether, the results obtained during the accomplishment and completion of this thesis
prove the successful use of human adipose stem cells for osteochondral tissue engineering, as
mechanically responsive cell source, which, in combination with appropriate growth factors,
generate both cartilage and bone compartments. Besides the success obtained with dynamic
culturing, it was proven that hASC have great potential to be used as single cell source for the
development of vascularized bone grafts.network. Three strategies were evaluated by changing spatio-temporal cues, but only one of
the combinations, in particular the osteo-induction of hASC seeded to silk scaffold for 3 weeks,
followed by addition of fibrin-encapsulated hASC to which vasculogenic cues were provided for
2 weeks, resulted in the most promising outcomes towards vascularized bone grafts.
The final experimental design focused on the development of an in vitro model for studies of
heterotypic cellular interactions that couple blood vessel formation with osteogenesis by using
human umbilical vein endothelial cells (HUVECs) and human bone marrow mesenchymal stem
cells (hMSCs). In this study, we hypothesized that the sequential application of growth factors,
to firstly induce the formation of stable vasculature and subsequently initiate osteogenic
differentiation, could provide a biologically-inspired in vitro model of bone vascularization. Two
important findings resulted from these studies: (i) vascular development needs to be induced
prior to osteogenesis, and (ii) the addition of additional hMSCs at the osteogenic induction
stage improves both tissue outcomes, and anastomosis of vascular networks with the host
(SCID mice) vasculature.
Taken altogether, the results obtained during the accomplishment and completion of this thesis
prove the successful use of human adipose stem cells for osteochondral tissue engineering, as
mechanically responsive cell source, which, in combination with appropriate growth factors,
generate both cartilage and bone compartments. Besides the success obtained with dynamic
culturing, it was proven that hASC have great potential to be used as single cell source for the
development of vascularized bone grafts. investigados no contexto do desenvolvimento ósseo. A fim de vascularizar o enxerto ósseo
desenvolvido, foram exploradas condições específicas de regulação espaço-temporal de
células e fatores de crescimento.
Para este propósito, cinco estudos experimentais foram realizados. O primeiro estudo focado
no desenvolvimento de dois bioreatores visou gerar pressão hidrostática (HP) para a cultura
dinâmica do tecido cartilaginoso. Consideramos como hipótese que a formação de cartilagem
poderia ser aumentada através da aplicação de tais estímulos fisiológicos, tanto em células
primárias (condrócitos) (septo nasal humano - HNC) ou células-estaminais (células estaminais
do tecido adiposo humano - hASC), cultivadas em hidrogéis de goma gelana, variando a
frequência e magnitude de carga. No estudo HNC, o melhor desenvolvimento de tecido foi
conseguido para o regime de HP pulsátil, enquanto que no estudo hASC, os melhores
resultados foram obtidos através da aplicação de níveis fisiológicos de HP (5 MPa), como
evidenciado pela expressão genética de agrecano, colagénio tipo II e sox-9, assim como
através da coloração metacromática da matriz da cartilagem e imunolocalização de
colagénios.
O próximo passo pretendia avaliar os efeitos da arquitectura e propriedades biomecânicas de
suportes, a fim de otimizar suportes de seda para a engenharia de tecido ósseo. Suportes de
seda foram fabricados usando diferentes solventes (aquoso vs hexafluoro-2-propanol - HFIP),
tamanhos de poros (250-500μm versus 500-1000μm) e estruturas (poros lamelar versus
esférica). Dado o grande potencial de hASC para terapias celulares e engenharia de tecidos,
em especial do tecido ósseo, os suportes de seda e hASC constituem dois componentes
promissores, que ainda não foram previamente investigados em combinação. O suporte
composto por seda-HFIP, com poros esféricos de 400-600 μm, demonstrou melhor
desempenho do que qualquer outro suporte, enquanto os suportes com estrutura lamelar
demonstraram melhor desempenho do que os suportes com poros esféricos.
Este suportes de seda-HFIP foram posteriormente utilizados para os estudos de cultura
dinâmica, onde foram avaliados os efeitos da perfusão pulsátil sobre a expressão óssea por
hASC. Consideramos como hipótese que a formação de osso poderia ser aumentada através
da replicação de estímulos fisiológicos - fluxo intersticial pulsátil - para as células cultivadas
em suportes porosos utilizando bioreatores com perfusão do meio de cultura. Esta hipótese foi
confirmada, uma vez que o melhor desenvolvimento de tecido foi obtido para a sequência de 2 semanas de fluxo constante e 3 semanas de fluxo pulsátil, como evidenciado pela expressão
genética, composição do enxerto, histomorfologias e propriedades biomecânicas.
O desafio seguinte consistia em vascularizar os enxertos ósseos desenvolvidos. Mais exigente
foi o uso da mesma fonte celular - hASC. Numa perspectiva clínica, o ideal seria desenvolver
enxertos ósseos vascularizados a partir de uma colheita celular única obtida do paciente.
Consideramos como hipótese que uma aplicação sequencial de fatores de crescimento
endoteliais e osteogénicos em hASC cultivadas em biomateriais (suportes de seda-HFIP), com
diferentes períodos de adição de células frescas, poderia beneficiar o desenvolvimento de
osso contendo uma rede vascular integrada. Três estratégias foram avaliadas mas apenas
uma das combinações forneceu resultados promissores para o desenvolvimento de enxerto
ósseo vascularizado, em particular a osteo-indução das hASC aderidas ao suporte de seda
durante 3 semanas, seguido pela adição de hASC encapsuladas em fibrina, às quais foram
fornecidas fatores vasculogénicos durante 2 semanas.
O desenho experimental final concentrou-se no desenvolvimento de um modelo in vitro para
estudo de interações celulares heterotípicas que combinem formação de vasos sanguíneos
com osteogénese, usando células endoteliais do cordão umbilical humano (HUVECs) e
células-estaminais mesenquimatosas da medula óssea humana (hMSCs). Neste estudo,
testamos a hipótese da aplicação sequencial de fatores de crescimento, em primeiro lugar,
induzir a formação de vasos estáveis e, posteriormente, iniciar a diferenciação osteogénica,
poder fornecer um modelo in vitro de vascularização óssea, biologicamente inspirado. Duas
conclusões importantes resultaram deste estudo: (i) o desenvolvimento vascular necessita de
ser induzida antes da osteogénese, e (ii) a adição de hMSCs adicionais na fase de indução
osteogénica melhora os resultados do tecido, assim como a anastomose das redes vasculares
com a vasculatura do animal recetor (ratinhos SCID).
Analisados em conjunto, os resultados obtidos durante a realização e conclusão desta tese
provam o sucesso do uso de células estaminais do tecido adiposo humano para engenharia
de tecidos osteocondrais, como fonte de células mecanicamente sensíveis às distintas forças
de estimulação biomecânica, que, em combinação com os fatores de crescimento adequados,
desenvolveram os compartimentos cartilagíneo e ósseo. Além do sucesso obtido com a
cultura dinâmica, foi comprovado que as hASC apresentam grande potencial para serem
utilizadas como fonte celular única para o crescimento de enxertos ósseos vascularizados.Financially, I want to thank the Portuguese Foundation for Science and Technology (FCT) for providing me the PhD grant (SFRH/BD/42316/2007), as well as funding from the American National Institute of Health (NIH) for GVN’s lab (DE161525 and EB02520), which allowed all this to happen
Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14
Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences
Recommended from our members
Technology catalogue. Second edition
The Department of Energy`s (DOE`s) Office of Environmental Management (EM) is responsible for remediating DOE contaminated sites and managing the DOE waste inventory in a safe and efficient manner. EM`s Office of Technology Development (OTD) supports applied research and demonstration efforts to develop and transfer innovative, cost-effective technologies to its site clean-up and waste-management programs within EM. The purpose of the Technology Catalogue is to: (a) provide performance data on OTD-developed technologies to scientists and engineers responsible for preparing Remedial Investigation/Feasibility Studies (RI/FSs) and other compliance documents for the DOE`s clean-up and waste-management programs; and (b) identify partnering and commercialization opportunities with industry, other federal and state agencies, and the academic community
Aerospace medicine and biology: A continuing bibliography with indexes (supplement 337)
This bibliography lists 400 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during May 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance
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