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At least 1,369 records · Page 76Linked to original sources
PubMed2001

Water quality response to riparian restoration in an agricultural watershed in Vermont, USA.

Achievement of management goals for Lake Champlain (Vermont/New York, USA and Quebec, Canada) will require reduction of agricultural phosphorus loads, the dominant nonpoint source in the Basin. Cost-effective phosphorus reduction strategies need reliable treatment techniques beyond basic cropland and waste management practices. The Lake Champlain Basin Agricultural Watersheds National Monitoring Program (NMP) Project evaluates the effectiveness of livestock exclusion, streambank protection, and riparian restoration practices in reducing concentrations and loads of nutrients, sediment, and bacteria in surface waters. Treatment and control watersheds in northwestern Vermont have been monitored since 1994 according to a paired-watershed design. Monitoring consists of continuous stream discharge recording, flow-proportional sampling for total P, total Kjeldahl N, and total suspended solids, grab sampling for indicator bacterial, and land use/agricultural monitoring. Strong statistical calibration between the control and treatment watersheds has been achieved. Installation of riparian fencing, protected stream crossings, and streambank bioengineering was completed in 1997. Early post-treatment data suggest significant reduction in P concentrations and loads and in bacteria counts in the treated watershed. Monitoring is scheduled to continue through 2000.

Agriculture↗
PubMed2001

Mechanotransduction in endothelial responses to shear stress: review of work in Dr. Chien's laboratory.

Shear stresses play an important role in vascular biology in health and disease. While disturbed flows with low shear stresses in the bends and bifurcations of the arterial tree are atherogenic, laminar flows with high shear stresses in the straight part of the vessel is atheroresistant. Thus, elucidation of the mechanotransduction mechanism in vascular endothelial cells in response to shear stress has become an important research topic among bioengineers and vascular biologists. Here is a summary of studies performed in Dr. Shu Chien's laboratory on shear stress-induced signal transduction and gene expression during the period from 1992-1999. These studies, together with efforts from other research groups, demonstrate that integrins, which are transmembrane molecules that interact with both extracellular matrices and intracellular cytoskeleton and kinases in the focal adhesions, are important in mechanotransduction. This hypothesis is mainly supported by the similarity between cellular and molecular events elicited by shear stress and those activated during the integrin-mediated cell attachment to extracellular matrices. Evidence is also provided to show that the dynamic and specific interaction between integrin and extracellular matrices is essential for mechanotransduction.

Chemokine CCL2↗
PubMed1989

Sustaining humans in space.

One goal of NASA's Ames Research Center is to extend the presence of humans in space. Biomedical research, human performance, and life-support systems form the core of the Ames program. Major questions highlight how the effects of microgravity on living systems are modified by exercise, artificial gravity, autogenic feedback training, and nutrition. Bioengineering and life science studies include humans, animals, and plants. Ames investigators collaborate extensively with outside university and commercial scientists, both within the United States and internationally.

Bone Density↗
PubMed1997

Milestones of space medicine development in Russia (establishment and evolution of the Institute of Biomedical Problems).

This paper describes the history of the Institute of Biomedical Problems (IMBP): its birth and development. IMBP's directors were: Andrei V. Libedinsky (1963-1965), Vasily V. Parin (1965-1967), Oleg G. Gazenko (1968-1988), and Anatoly I. Grigoriev (1988 to the present). Most of the early employees of IMBP came from the USSR Air Force Institute of Aviation Medicine and the USSR Ministry of Health Institute of Biophysics. The major goals of IMBP were: development of a system of medical monitoring and support of long-duration space missions, selection and training of civilian crew members, bioengineering testing of flight equipment, and development of life support system concepts and requirements. The paper presents major results of the above research activities.

Aerospace Medicine↗
PubMed2001

Advances in medical biological defense technology.

No single medical countermeasure will meet the needs for defense against all biological threats in all possible scenarios (civilian, military, clinical, and environmental). As the threat of genetically engineered organisms rises and the risk increases that these organisms might escape detection and successful treatment, it will be necessary to use advances in bioengineering to combat these new threats. This article presents several novel approaches taken by the DoD in collaboration with industry partners and other federal laboratories to produce improved biowarfare vaccines, diagnostics, and treatments. In the future, the United States must remain on the cutting edge of biotechnology and continue to predict the next areas of research necessary to maintain protection for the state-of-the-art warfighter on the battlefield.

Biological Warfare↗
PubMedDate not supplied

Morphological aspects of an artificial skin.

Culture technology have permitted the generation of an artificial skin using human neonatal stem cells. A major advantage of this model is that epithelial-mesenchymal interactions are maintained. We have studied some morphological aspects concerning tissue organisation and cell differentiation using immunohistochemistry and electron microscopy. The epidermal equivalent was composed by a stratified and keratinized epithelium. The cells of this epithelium were cytokeratin-positive and disposed in different layers corresponding to natural skin, i.e. basal, spinous, granular and keratinized layers. The ultrastructural aspects concerning keratinocyte differentiation were comparable to natural epidermis. The dermal equivalent was composed by a loose connective tissue. The cells of the dermal equivalent were vimentin-positive and belonged to the fibroblast lineage. Although poorly developed, a basement membrane was detectable in the dermo-epidermal junction. The organ architecture and the high level of cell differentiation suggest that this bioengineered skin might be considered a useful substitute for natural skin in clinical, biological and pharmacological applications.

Basement Membrane↗
PubMed2001

[Important bio-thermal physical problems and latest advancement in laser cell engineering].

The recently emerging technique of laser microsurgery (optical tweezers, optical scissors, etc.) is providing a new precise, sterile method for the cell engineering practices such as introduction of external gene into an object cell, cell-fusion, and trapping or transportation of microscopic objects (cells or chromosomes etc.). The thermal effects thus induced usually proved to be critical factors for successful operation of this method. In order to meet the requirement for the rapid development in this territory, some important bio-thermal physical problems and the corresponding research subjects in this area were comprehensively summarized. Difficulties and critical issues were discussed. The latest advancement of the laser cell engineering was also described. This review is attempted to bridge up the gap between bioengineering and thermal science fields and then to enhance the rapid progress of laser microsurgery.

Biotechnology↗
PubMed2001

[Repair of chondral defects of the knee using a combination of autologous chondrocytes and osteochondral allograft--an animal model. Part I: in vitro culture of autologous chondrocytes].

PURPOSE OF THE STUDY: In the study we used in vitro cultivated autologous chondrocytes in combination with osteochondral allografts for the treatment of local defects of articular cartilage on the animal model (rabbit). MATERIAL: Chondrocytes for in vitro cultivation were harvested by biopsy of articular cartilage of rabbit. For the monolayer cultivation we used Nutrient mix F 12 (Gibco BRL) with addition of Lascorbic acid (50 micrograms/ml, Sigma) and insulin-trasferin-selenium (A 6.26 micrograms/ml, Gibco BRL), 20% of fectal serum (Gibco BRL) and antibiotic antimycotic solution (Gibco BRL). Cultivation of chondrocytes took place at 37 degrees in the atmosphere of 5% CO2. Multiplied chondrocytes re-suspended in fibrin glue in combination with two osteochondral allografts were used for the reparation of artificial defect of the rabbit cartilage. METHODS: For the analysis of collagen type II in the cultivation medium we used the principle of salting out by 30% ammonium sulphate and subsequent pepsinization in an acid environment with a repeated salting out by means of 2M of NaCl. Precipitates were dissolved in 5.0 M of acetic acid and used for SDS PAGE and immunoblotting. As a detection system we used ECL (Amersham/Pharmacia Biotech). RESULTS: The final average number of chondrocytes multiplied by monolayer cultivation was 1.10(5). The presence of collagen of type II has proved the preservation of the original phenotype of chondrocytes during cultivation. DISCUSSION: Bioengineering use of cell and tissue cultivation provides new options of the treatment of defect of connective tissue. Transplantation of autologous chondrocytes in combination with osteochondral allografts is on the basis of our results obtained so far a promising therapy. CONCLUSION: The aim of our work was an ex vivo expansion of autologous chondrocytes for the purpose of cell transplantation.

Animals↗
PubMed2001

High bacterial load in asymptomatic diabetic patients with neurotrophic ulcers retards wound healing after application of Dermagraft.

Diabetic neuropathic foot ulcers are a major healthcare burden. These chronic wounds always have a bacterial load, and although normal flora is not harmful, increased tissue burden may impede healing before clinical signs of infection are evident. In this study, chronic noninfected diabetic neuropathic foot ulcers (those with adequate blood supply and pressure offloading) were assessed for bacterial burden immediately before the application of a skin substitute. Eight patients with diabetic neuropathic foot ulcers greater than 1 cm2 and free of necrotic tissue had 3-mm tissue biopsies taken from the ulcer base for quantitative bacteriology. Five of the eight patients (75%) had greater or equal to 10(5) colony forming units/gram organisms present despite the absence of clinical signs of infection. Wound healing rates were linked to bacterial load as determined from quantitative biopsy--no growth was associated with a wound healing rate of 0.2 cm per week, 10(5) to 10(6) colony forming units/gram was associated with a healing rate of 0.15 cm per week, and greater than 10(6) colony forming units/gram was associated with 0.05 cm/per week healing rate. High bacterial burden impeded healing both before and after the application of the skin substitute. The authors will change their clinical practice to assess all diabetic neuropathic foot ulcers using quantitative skin biopsies before applying skin substitutes. All patients will be treated with combination antibiotics and repeat biopsies obtained with decreased bacterial burden (< 10(6) colony forming units/gram) prior to using any bioengineered skin substitute or growth factor treatment.

Aged↗
PubMed2002

Phosphorus reductions following riparian restoration in two agricultural watersheds in Vermont, USA.

Achievement of management goals for Lake Champlain (Vermont/New York, USA and Quebec, Canada) will require significant reductions of phosphorus (P) loads from agriculture, the dominant diffuse source in the basin. Cost-effective P reduction strategies must be based on reliable treatment techniques beyond basic erosion control and animal waste storage practices. The Lake Champlain Basin Agricultural Watersheds National Monitoring Program (NMP) Project evaluates the effectiveness of low-cost livestock exclusion, streambank protection, and riparian restoration practices in reducing concentrations and loads of diffuse-source pollutants from grazing land at the watershed level. Treatment and control watersheds in northwestern Vermont have been monitored since 1994 according to a paired-watershed design. Monitoring includes continuous stream discharge recording, flow-proportional sampling for total P and other pollutants, and documentation of land use and agricultural management activities. Strong statistical calibration between the control and treatment watersheds has been achieved. Landowner participation in the land treatment program was entirely voluntary and all treatments were 100% cost-shared by the project and cooperators. Installation of riparian fencing, alternative water supplies, protected stream crossings, and streambank bioengineering was completed in 1997 at a cost of less than US$40,000. The paired-watershed design was effective in controlling for the influence of extreme variations in precipitation and streamflow over six years of monitoring. Two years of post-treatment data have documented significant reductions in P concentrations and loads from both treated watersheds. Reductions of approximately 20% in mean total P concentration and approximately 20-50% in mean total P load have been observed, with greater reductions occurring in the watershed receiving more extensive treatment. The effectiveness of riparian zone restoration in P reduction tended to be lower during periods of very high runoff, especially outside the growing season.

Agriculture↗
PubMedDate not supplied

[Analysis of attitudes about abortion].

Today two clear trends can be discerned in the development of attitudes about abortion over the last century or so. The first corresponds to that category of "bio-power" described by Foucault as a bio-politics of the population. The second trend, closely related, concerns the transformation of abortion from a largely criminal to a largely therapeutic procedure, that is, one which is said to be performed in the interests of preserving or enhancing the health and well-being of the woman or her existing children. This paper analysis the attitudes about abortion exploring the responses of the Medical Bioengineering Faculty's students to a series of questions about the conditions under which legal abortions should be available and tried to identify some of the reasons why abortion attitudes vary from person to person.

Abortion, Induced↗
PubMed2002

Sequence-specific assignments of proton NMR resonance peaks and analysis of secondary structural elements of LC1, a novel antibacterial polypeptide.

LC1 is a type of novel antibacterial polypeptide secreted by a Bacillus subtilis strain. It consists of 47 residues. Using bioengineering, LC1 was expressed in E.coli DH5alpha by using recombinant plasmid PBVAB16. By means of two-dimensional DQF-COSY, TOCSY and NOESY spectroscopies, protons of all 47 residues are identified. The studies show that the secondary structures of LC1 are principally anti-parallel beta sheets and extended conformations. It was speculated that there may be a hydrophobic core around Trp(23) in its three-dimensional structure.

Amino Acid Sequence↗
PubMed2002

Biodegradable polymer grafts for surgical repair of the injured spinal cord.

PURPOSE: Biodegradable polymers have been used in the surgical repair of peripheral nerves, but their potential for use in the central nervous system has not been exploited adequately. This article discusses concepts related to the engineering of a biodegradable polymer graft for surgical repair of the injured spinal cord and explores the potential means by which such a device might promote axon regeneration and functional recovery after spinal cord injury. CONCEPT: A biodegradable polymer implant with controlled microarchitecture can be engineered, and its composition can be optimized for implantation in the spinal cord. RATIONALE: The use of a biodegradable polymer implant has the dual advantages of providing a structural scaffold for axon growth and a conduit for sustained-release delivery of therapeutic agents. As a scaffold, the microarchitecture of the implant can be engineered for optimal axon growth and transplantation of permissive cell types. As a conduit for the delivery of therapeutic agents that may promote axon regeneration, the biodegradable polymer offers an elegant solution to the problems of local delivery and controlled release over time. Thus, a biodegradable polymer graft would theoretically provide an optimal structural, cellular, and molecular framework for the regrowth of axons across a spinal cord lesion and, ultimately, neurological recovery. CONCLUSION: Biodegradable polymer grafts may have significant therapeutic potential in the surgical repair of the injured spinal cord. Further research should be focused on the bioengineering, characterization, and experimental application of these devices.

Absorbable Implants↗
PubMed2000

Treatment of Venous Ulcers Using a Bilayered Living Skin Construct.

Venous ulcers are a common cause of pain and suffering in the elderly US population. Up to 1 million individuals suffer from this disease, and the true costs in terms of medical care and quality of life are only beginning to be appreciated. Bioengineered skin constructs are being used increasingly to treat venous ulcers with some success and can be used if traditional first-line treatment methods fail.

Journal Article↗
PubMed2002

[Comparative study of human fetal and adult bone marrow derived mesenchymal stem cells].

OBJECTIVE: To explore the differences of phenotype and biological characteristics between fetal and adult bone marrow derived mesenchymal stem cells. METHODS: Mononuclear cells from 4-5 months old human aborted fetus and normal adult bone marrow were cultured in SF medium to obtain mesenchymal stem cells. The growth curve, cell cycle, immunophenotype, in vitro expansion potential, differentiation capacities were investigated. RESULTS: The adherent fetal and adult bone marrow-derived cells cultured in the absence of differentiation stimuli gave rise to a population of cells with phenotypical features of mesenchymal stem cells (MSC). These MSCs were similar in cell morphology and antigenic phenotype. The proliferative and multilineage differentiation potential of the bone marrow derived MSC from the fetus is higher than that from the adult, but the adherent ability of the MSCs from the adult is higher than that from the fetus. CONCLUSION: Fetal bone marrow derived MSCs should be enough to sustain a steady supply of low differentiated cells for proliferation, hence an abundant and accessible cellular reservoir for stem cell bioengineering, whereas adult bone marrow derived MSCs are more useful in hematopoietic reconstitution in bone marrow transplantation.

Adult↗
PubMed2003

[Regeneration of the cornea].

The cornea is a transparent, colorless tissue that functions as the optical surface of the eye. Transparency is vital for useful vision, which can be compromised by disorders to the corneal epithelium, stroma or endothelium. Transplantation of donor corneas is the standard surgical procedure for irreversible damage to the tissue. However, Japan, as well as many countries across the globe, are suffering from a shortage of donor supplies. Recent developments in bioengineering techniques have opened the way for the possible development of regenerated tissue from cultured progenitor cells. An artificial cornea with all the necessary cell components may become available in the near future.

Amnion↗
PubMed2003

Measuring information flow in nonlinear systems--a modeling approach in the state space.

Directional information flow between coupled nonlinear systems is of practical interest in many areas like bioengineering, chemistry, physics and electrical engineering. Due to the high complexity and nonlinearity of the coupled chaotic systems, linear modeling approaches may fail to capture the proper dynamics and thus the proper directional information flow. This necessitates novel approaches to analyze signals derived from such systems. This paper proposes a novel approach for detecting such directional information flows between the subsystems involved. The dependability of the method is illustrated using coupled chaotic oscillators in various coupling configurations.

Causality↗
PubMed2003

University of Wyoming, College of Engineering, undergraduate design project: star tracer.

The University of Wyoming received funding in the spring of 2002 from the National Science Foundation Division of Bioengineering and Environmental Systems in order to complete undergraduate design projects. One design project that was chosen by the College of Engineering involved partnering with the College of Education. The College of Education's Special Education Department needed some visual teaching aids to be redesigned and then built. Two undergraduate students were hired throughout the summer of 2002 under NSF REU funding in order to develop thirty new teaching devices. These devices were going to be used to educate middle school students about the effects of possessing a learning disability. The teaching aids are specifically designed for simulating the affects of dyslexia. The new teaching aids required improved transportability and durability, quicker setup time, and a lighter weight. Throughout the summer, the teaching aids were redesigned and built by an undergraduate student team from the College of Engineering, and have since provided many benefits for the state of Wyoming.

Biomedical Engineering↗