Low gravity on earth by magnetic levitation of biological material

The use of a magnetic field gradient levitation apparatus as a tool for investigating gravisensing mechanisms in biological systems and as a low gravity simulator for biological systems is described. The basic principles are described. Differences between its application to pure materials and the heterogeneous materials of biological materials are emphasized.     

A systematic methodology for selecting decontamination strategies following a biocontamination event

Decontamination and recovery of a facility or outdoor area after a wide-area biological incident involving a highly persistent agent (eg, Bacillus anthracis spores) is a complex process that requires extensive information and significant resources, which are likely to be limited, particularly if multiple facilities or areas are affected. This article proposes a systematic methodology for evaluating information to select the decontamination or alternative treatments that optimize use of resources if decontamination is required for the facility or area. The methodology covers a wide range of approaches, including volumetric and surface decontamination, monitored natural attenuation, and seal and abandon strategies. A proposed trade-off analysis can help decision makers understand the relative appropriateness, efficacy, and labor, skill, and cost requirements of the various decontamination methods for the particular facility or area needing treatment--whether alone or as part of a larger decontamination effort. Because the state of decontamination knowledge and technology continues to evolve rapidly, the methodology presented here is designed to accommodate new strategies and materials and changing information.     

Ambient air levels of Aspergillus fumigatus and thermophilic actinomycetes in a residential neighborhood near a yard-waste composting facility

Composting is a biological process that has thepotential to emit large quantities ofbioaerosols and, therefore, could adverselyaffect public health. Numerous previousstudies have demonstrated bioaerosol levelselevated above background adjacent tocomposting waste materials, but effects onoffsite bioaerosol levels due tocomposting-facility bioaerosol emissions havenot been extensively investigated. Of the fewsuch studies published, most have not foundelevated compost-related bioaerosols downwindfrom the composting operation. We investigatedviable Aspergillus fumigatus andthermophilic actinomycete levels upwind anddownwind of a large yard-waste compostingfacility and sought to determine whether levelsin a residential neighborhood near the facilitywere elevated above background levels due tofacility bioaerosol emissions. Mean bioaerosollevels at the composting facility weresignificantly higher than the mean backgroundlevels, exceeding the background means byroughly 20-fold. When a neighborhood samplingsite about 500 m from the facility was in thedownwind direction mean levels weresignificantly higher than for other winddirections, and excursions well abovebackground levels were significantly morefrequent than at background sites. There was asignificant temporal correlation betweenbioaerosol levels at the composting facilityand the downwind sampling site. The resultsindicate that bioaerosol emissions from a largeyard-waste composting facility cansignificantly increase bioaerosol exposurelevels at least 500 m downwind from thefacility.     

A newly designed and constructed 20 kHz magnetic field exposure facility for in vivo study

Exposure to man-made electromagnetic fields has increased over the past century. As a result of exposure to these fields, concerns have been raised regarding the relationship between electromagnetic fields and human health. Interest in the biological and health effects of intermediate frequency (IF) magnetic fields has grown recently because of the increase in public concern. In order to investigate whether IF magnetic fields have biological effects, we have developed a 20 kHz (IF) magnetic field exposure system for in vivo studies. The exposure facility was designed to study the biological effects of IF magnetic field on laboratory animals. The facility consists of a 9 m x 9 m x 5 m high room containing seven separate rooms including a 5.3 m x 4.5 m x 3 m high specific-pathogen free exposure room. The dimensions of the exposure system are 1.6 m x 1.6 m x 1.616 m high located inside this exposure room. The system is designed to provide magnetic fields up to 200 microT at 20 kHz with the uniformity within +/-5% over the space occupied by animals. After constructing the facility, performance tests were carried out. As a result, it was confirmed that our facility met requirements for evaluation of the biological effects of IF magnetic field on small animal experiments. In this paper, the design, construction, and results of evaluation of an animal exposure facility for the in vivo biological effects of an IF magnetic field are described.     

A reliable epoxy resin mixture and its application in routine biological transmission electron microscopy

Although there are many papers in the literature on materials and procedures for the embedding of tissue for transmission electron microscopy (TEM), most recent publications have emphasized techniques for specialized applications. Although these may in many cases also be suitable for routine applications in addition to the specialized applications for which they were developed, this may not be clear from the literature. This paper describes the formulation and suggested procedures for the use of an epoxy resin mixture which has been routinely used by novice and experienced workers with success for a wide variety of biological TEM investigations in a multi-user multi-disciplinary EM facility. Results are given of the use of this embedding medium in the investigation of a variety of tissue types.     

Management strategies for controlling endemic and seasonal mouse parvovirus infection in a barrier facility

Despite improved diagnostic and rederivation capabilities, research facilities still struggle to manage parvovirus infections (e.g., mouse parvovirus (MPV) and minute virus of mice) in mouse colonies. Multi-faceted approaches are needed to prevent adventitious organisms such as MPV from breaching a barrier facility. In this article, the authors document recent changes to the Salk Institute's animal care program that were intended to help manage mouse parvovirus in the barrier facility. Specifically, the Institute started to use a new disinfectant and to give mice irradiated feed. The authors found an association between these modifications and a reduction in MPV incidence and prevalence in endemically infected colonies. These data suggest that using irradiated feed and appropriate disinfectants with contemporary management practices can be an effective plan for eradicating or controlling MPV infection in a research facility. The authors recommend further study of the environmental risk factors for parvovirus infection and of potential biological interactions associated with the use of irradiated feed.     

A controlled-temperature apparatus for measurement of hydrogen peroxide production.

An apparatus is described which permits continuous assays of hydrogen peroxide production from biological materials, including whole cells. Temperature in the assay mixture is controlled, for work above or below room temperatures. Data obtained by use of the apparatus are presented, as illustration of the effects of temperature upon peroxide output.     

Construction and organization of a BSL-3 cryo-electron microscopy laboratory at UTMB

A unique cryo-electron microscopy facility has been designed and constructed at the University of Texas Medical Branch (UTMB) to study the three-dimensional organization of viruses and bacteria classified as select agents at biological safety level (BSL)-3, and their interactions with host cells. A 200 keV high-end cryo-electron microscope was installed inside a BSL-3 containment laboratory and standard operating procedures were developed and implemented to ensure its safe and efficient operation. We also developed a new microscope decontamination protocol based on chlorine dioxide gas with a continuous flow system, which allowed us to expand the facility capabilities to study bacterial agents including spore-forming species. The new unified protocol does not require agent-specific treatment in contrast to the previously used heat decontamination. To optimize the use of the cryo-electron microscope and to improve safety conditions, it can be remotely controlled from a room outside of containment, or through a computer network world-wide. Automated data collection is provided by using JADAS (single particle imaging) and SerialEM (tomography). The facility has successfully operated for more than a year without an incident and was certified as a select agent facility by the Centers for Disease Control.     

Porous zirconia: a new support material for enzyme immobilization

Four different proteases (trypsin, chymotrypsin, papain and pepsin) were covalently attached to the surface of a new type of porous zirconia, as well as a conventional porous silica, activated with 3-isothiocyanatopropyltriethoxy silane (NCS-silane). The immobilization efficiency onto the porous zirconia material was evaluated in terms of the amount of enzyme attached to the particles and from the biological activity remaining after the immobilization step. The results were compared with the corresponding experiments with a porous silica of similar surface area/g support material. In addition, the storage stability of the modified zirconia and silica biocatalysts were evaluated. These results indicated that specific immobilized enzyme biocatalysts can be achieved with this new zirconia support material which exhibits different properties to those observed with the more conventional silica-based materials. Moreover, the results with the enzyme-zirconia biocatalysts also indicate different characteristics when compared with data for the same enzymes immobilized under similar buffer conditions to organic support materials as previously described by various other investigators. The advantages of zirconia-based immobilized enzyme biocatalysts in terms of their density and chemical robustness are also described relative to other alternative support materials currently in use.     

Polymer microarrays for high throughput discovery of biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format (1). Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique (2). This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion (3-5). Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction (6). HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials (5,3).     

Gravitational biology of integrative organisms and ecological system--the road map of space activities]

History of the International Space Station, ISS, and planning of its scientific use are described in this essay. Fundamental gravitational biology and its facility on the ISS have been identified to have the highest priority to conduct scientific experiments with variable G environment in orbit. The road map of space activities is clearly directing the efforts toward manned Mars exploration. The Centrifuge is a core element of the facilities dedicated to this endeavor. Several research subjects are discussed with the results obtained from the past space experiments. Direct effects of gravity on the biological system at the level of integrative organisms are major subjects of study that will be conducted on the large scaled centrifuge.     

The development of spaceflight experiments with Arabidopsis as a model system in gravitropism studies

Experiments with Arabidopsis have been developed for spaceflight studies in the European Space Agency's Biorack module. The Biorack is a multiuser facility that is flown on the United States Space Shuttle and serves as a small laboratory for studying cell and developmental biology in unicells, plants, and small invertebrates. The purpose of our spaceflight research was to investigate the starch-statolith model for gravity perception by studying wild-type (WT) and three starch-deficient mutants of Arabidopsis. Since spaceflight opportunities for biological experimentation are scarce, the extensive ground-based testing described in this paper is needed to ensure the success of a flight project. Therefore, the specific aims of our ground-based research were: (1) to modify the internal configuration of the flight hardware, which originally was designed for large lentil seeds, to accommodate small Arabidopsis seeds; (2) to maximize seed germination in the hardware; and (3) to develop favorable conditions in flight hardware for the growth and gravitropism of seedlings. The hardware has been modified, and growth conditions for Arabidopsis have been optimized. These experiments were successfully flown on two Space Shuttle missions in 1997.     

Modeling of an Aerobic Membrane Bioreactor for Wastewater Treatment

The goal of this work is to develop a mathematical model to describe a continuous aerobic membrane bioreactor (MBR) for the treatment of different kinds of wastewater. Firstly, the experimental setup and the materials and methods to obtain data for the model verification are described. Secondly, a black box model is developed and verified for size containing wastewater. The model calculates output streams and concentrations from input streams and compositions using distribution coefficients. These coefficients are derived from experimental data. In a third step, two shortcut models of different complexity are developed. Both shortcut models use the black box balancing as a basis. However, the component balances for carbon and oxygen are no longer modeled by constant distribution coefficients. The basic shortcut model introduces Monod kinetics to modify the carbon balance. The enhanced shortcut model introduces transport laws for dissolved oxygen supply and combines the Monod kinetics with an additional term for oxygen limitation to model biological growth. The models show an increasing degree of agreement.     

Computer model for glucose-limited growth of a single cell of Escherichia coli B/r-A

A computer model is described which is capable of predicting changes in cell composition, cell size, cell shape, and the timing of chromosome synthesis in response to changes in external glucose limitation. The model is constructed primarily from information on unrestricted growth in glucose minimal medium. The ability of the model to make reasonable quantitative predictions under glucose-limitation is a test of the plausibility of the basic biochemical mechanisms included in the model. Such a model should be of use in differentiating among competing hypotheses for biological mechanisms and in suggesting as yet unobserved phenomena. The last two points are illustrated with the testing of a mechanism for the control of the initiation of DNA synthesis and predictions on cellwidth variations during the division cycle.     

Use of a tapered fluidized bed as a Continuous bioreactor

Reactor systems based on tapered fluidized beds are being developed for aqueous bioprocesses in which adhering microorganisms or immobilized active biological fractions are used. The use of a fluidized bed prevents biomass buildup, accommodates particulates in the feed stream, is compatible with gas sparging, and allows easy removal or addition of the active materials. The tapered reactor tends to stabilize the fluidized bed, thus allowing a much wider range of operating conditions. Preliminary experimental results and an empirical mathematical model of the tapered bed indicate that bed stability is associated with a decreasing velocity and void-fraction profile up the bed and the pressure drop across the bed decreases with increasing flow rates. The tapered fluidized bed bioreactor is being evaluated for use in the enzymatic production of hydrogen, microbiological denitrification, and microbiological degradation of coal conversion aqueous waste streams. The enzyme catalyzed conversion of lactose to glucose and galactose was used in the evaluation of the reactor concept.     

A glovebox with three levels of containment and clean room facilities for growing and handling biological material at physiologically correct gas compositions and with optimal quality assessment for tissue-engineering, ex vivo expansion, manipulation and gene therapy

Traditional two levels of containment provide enclosure and underpressure in order to avoid hazardous material to flow towards e.g. a crewmember and thereby cause severe harm. The present-day demands for laboratory safety have revealed a paradox: In the laboratory overpressure is needed to prevent contamination of biological material and under pressure is needed to prevent the pollution of the environment. A new type of combined workbench/incubator has been constructed to meet future regulatory demands for handling and growing human biological cellular material at safe constant physiological conditions: A so-called three levels of containment glovebox/workbench. This new invention avoids the hazards of prior technology. It sets new standards for proper handling of biological materials and will meet the coming safety demands from the growing field of tissue engineering and ex vivo biotechnology. The invention is computer controlled, has a build in cleaning facility for assuring a particle free and aseptic working facility. We now have invented a solution to the above paradox concerning laboratory safety that seems to fulfil the need for safe biological experiments in microgravity. This concept has already been applied into ground-based research and is expected in a few years also to be applied similarly in the ISS environment. Furthermore, handling biological material mimicking in vivo conditions ex vivo requires precise and stabile monitoring and regulation of the isotherm and isobar conditions. Handling stem cells requires in addition low to very low oxygen tension to mimic the stem cells natural habitats. Besides that, the ex vivo gaseous atmosphere and temperature surrounding the cells has to be of same correct composition and temperature as found in the body in order to mimic in vivo situations in such way, that scientifically correct, reproducible and comparable results can be achieved. This fact is strengthened by forthcoming regulations as being prepared by several international regulatory bodies. The new concept will find its use in microgravity biotechnology and will set new standards on ground and in microgravity in the field of basic research, tissue-engineering, production of patient specific cells and tissue, embryo-genesis and in vitro fertilisation, ex vivo expansion of blood progenitor cells, gene therapy etc.     

The development of spaceflight experiments withArabidopsis as a model system in gravitropism studies

Experiments withArabidopsis have been developed for spaceflight studies in the European Space Agency's Blorack module. The Biorack is a multiuser facility that is flown on the United States Space Shuttle and serves as a small laboratory for studying cell and developmental biology in unicells, plants, and small invertebrates. The purpose of our spaceflight research was to investigate the starch-statolith model for gravity perception by studying wild-type (WT) and three starch-deficient mutants ofArabidopsis. Since spaceflight opportunities for biological experimentation are scarce, the extensive ground-based testing described in this paper is needed to ensure the success of a flight project. Therefore, the specific aims of our ground-based research were: (1) to modify the internal configuration of the flight hardware, which originally was designed for large lentil seeds, to accommodate smallArabidopsis seeds; (2) to maximize seed germination in the hardware; and (3) to develop favorable conditions in flight hardware for the growth and gravitropism of seedlings. The hardware has been modified, and growth conditions forArabidopsis have been optimized. These experiments were successfully flown on two Space Shuttle missions in 1997.     

Production cost of a real microalgae production plant and strategies to reduce it

The cost analysis of a real facility for the production of high value microalgae biomass is presented. The facility is based on ten 3 m³ tubular photobioreactors operated in continuous mode for 2 years, data of Scenedesmus almeriensis productivity but also of nutrients and power consumption from this facility being used. The yield of the facility was close to maximum expected for the location of Almería, the annual production capacity being 3.8 t/year (90 t/ha·year) and the photosynthetic efficiency being 3.6%. The production cost was 69 €/kg. Economic analysis shows that labor and depreciation are the major factors contributing to this cost. Simplification of the technology and scale-up to a production capacity of 200 t/year allows to reduce the production cost up to 12.6 €/kg. Moreover, to reduce the microalgae production cost to approaches the energy or commodities markets it is necessary to reduce the photobioreactor cost (by simplifying its design or materials used), use waste water and flue gases, and reduce the power consumption and labor required for the production step. It can be concluded that although it has been reported that production of biofuels from microalgae is relatively close to being economically feasible, data here reported demonstrated that to achieve it by using the current production technologies, it is necessary to substantially reduce their costs and to operate them near their optimum values.     

Fluorescence Microscopy Applied to Entomology and Allied Fields

Fluorescence is a phenomenon observable in many substances including a wide range of biological constituents. By use of ultraviolet illumination and the proper fluorescent dyes, when needed, many details of structure and physiological differentiation are made apparent which by illumination with visible light are obscure.

The fluorescence microscope is a valuable adjunct to the study of fluorescence in biological materials. This instrument is discussed from a practical standpoint. The simplifications in the instrument which do not impair its efficiency are indicated.

The use of fluorochromes is discussed and a list of the most important of these is given. Important technics with the fluorescence microscope, including intravital microscopy, fluorescent photomicrography, and microspectroscopy, are described.     

Mechanical characterization of anisotropic planar biological soft tissues using large indentation: a computational feasibility study

Traditionally, the complex mechanical behavior of planar soft biological tissues is characterized by (multi)axial tensile testing. While uniaxial tests do not provide sufficient information for a full characterization of the material anisotropy, biaxial tensile tests are difficult to perform and tethering effects limit the analyses to a small central portion of the test sample. In both cases, determination of local mechanical properties is not trivial. Local mechanical characterization may be performed by indentation testing. Conventional indentation tests, however, often assume linear elastic and isotropic material properties, and therefore these tests are of limited use in characterizing the nonlinear, anisotropic material behavior typical for planar soft biological tissues. In this study, a spherical indentation experiment assuming large deformations is proposed. A finite element model of the aortic valve leaflet demonstrates that combining force and deformation gradient data, one single indentation test provides sufficient information to characterize the local material behavior. Parameter estimation is used to fit the computational model to simulated experimental data. The aortic valve leaflet is chosen as a typical example. However, the proposed method is expected to apply for the mechanical characterization of planar soft biological materials in general.