Biomedical subjects

J M Cassanto

Publications and source records attributed to J M Cassanto.

4 recordsLinked to original sources

PubMed2001

Bacterial biofilm formation under microgravity conditions.

Although biofilm formation is widely documented on Earth, it has not been demonstrated in the absence of gravity. To explore this possibility, Pseudomonas aeruginosa, suspended in sterile buffer, was flown in a commercial payload on space shuttle flight STS-95. During earth orbit, biofilm formation was induced by exposing the bacteria to sterile media through a 0.2-microm (pore size) polycarbonate membrane. Examination of these membranes by confocal microscopy revealed biofilms to be present and that these biofilms could persist in spite of vigorous agitation. These results represent the first report of biofilm formation under microgravity conditions.

Bacterial Adhesion↗

PubMed1996

Protein crystallization in low gravity by step gradient diffusion method.

Two-step crystallization experiments were conducted in low gravity employing a liquid-liquid diffusion method in an effort to eliminate problems associated with protein crystal growth under the supersaturating conditions required for nucleation. Experiments were performed in diffusion cells formed by the sliding of blocks on orbit. Step gradient diffusion experiments consisted of first exposing protein solutions in diffusion half-wells for brief periods to initiating buffer solutions of high precipitant concentrations to induce nucleation followed by expoure of the same protein solutions to solutions of lower precepitant concentration to promote growth of induced nuclei into crystals. To avoid convective disturbances that occur when solutions of discrepant densities are interfaced at normal gravity, crystallization of hen egg-white lysozyme and rabbit skeletal muscle aldolase by step gradient diffusion was investigated in low gravity on four NASA space shuttle flights. In general, the largest ctystals of both proteins formed at the highest initiating precipitant concentration used, which is consistent with nuclei formation upon brief exposure to high precipitant concentration, and that these nuclei are competent for sustained growth at lower precipitant concentration. The two-step approach dissociates nucleation events from crystal growth allowing parameters affecting nucleation kinetics such as time, precipitant concentration and temperature of nucleation to be varied separately from conditions used for post-nucleation growth.

Animals↗

PubMed1991

The BIMDA shuttle flight mission: a low cost microgravity payload.

This paper presents the design, operation and experiment protocol of the Bioserve sponsored flights of the ITA Materials Dispersion Apparatus Payload (BIMDA) flown on the Space Shuttle on STS-37. The BIMDA payload represents a joint effort between ITA (Instrumentation Technology Associates, Inc.) and Bioserve Space Technologies, a NASA Center for the Commercial Development of Space, to investigate the methods and commercial potential of biomedical and fluid science applications in the microgravity environment of space. The BIMDA payload, flown in a Refrigerator/Incubator Module (R/IM) in the Orbiter middeck, consists of three different devices designed to mix fluids in space; four Materials Dispersion Apparatus (MDA) Minilabs developed by ITA, six Cell Syringes, and six Bioprocessing Modules both developed by NASA JSC and Bioserve. The BIMDA design and operation reflect user needs for late access prior to launch (<24 h) and early access after landing (<2 h). The environment for the payload is temperature controlled by the R/IM. The astronaut crew operates the payload and documents its operation. The temperature of the payload is recorded automatically during flight. The flight of the BIMDA payload is the first of two development flights of the MDA on the Space Shuttle. Future commercial flights of ITA's Materials Dispersion Apparatus on the Shuttle will be sponsored by NASA's Office of Commercial Programs and will take place over the next three years. Experiments for the BIMDA payload include research into the following areas: protein crystal growth, thin film membrane casting, collagen formation, fibrin clot formation, seed germination, enzymatic catalysis, zeolite crystallization, studies of mixing effects of lymphocyte functions, and solute diffusion and transport.

Biotechnology↗

PubMed1988

Simulation of launch and re-entry acceleration profiles for testing of shuttle and unmanned microgravity research payloads.

Microgravity experiments designed for execution in Get-Away Special canisters, Hitchhiker modules, and Reusable Re-entry Satellites will be subjected to launch and re-entry accelerations. Crew-dependent provisions for preventing acceleration damage to equipment or products will not be available for these payloads during flight; therefore, the effects of launch and re-entry accelerations on all aspects of such payloads must be evaluated prior to flight. A procedure was developed for conveniently simulating the launch and re-entry acceleration profiles of the Space Shuttle (3.3 and 1.7 x g maximum, respectively) and of two versions of NASA's proposed materials research Re-usable Re-entry Satellite (8 x g maximum in one case and 4 x g in the other). By using the 7 m centrifuge of the Gravitational Plant Physiology Laboratory in Philadelphia it was found possible to simulate the time dependence of these 5 different acceleration episodes for payload masses up to 59 kg. A commercial low-cost payload device, the "Materials Dispersion Apparatus" of Instrumentation Technology Associates was tested for (1) integrity of mechanical function, (2) retention of fluid in its compartments, and (3) integrity of products under simulated re-entry g-loads. In particular, the sharp rise from 1 g to maximum g-loading that occurs during re-entry in various unmanned vehicles was successfully simulated, conditions were established for reliable functioning of the MDA, and crystals of 5 proteins suspended in compartments filled with mother liquor were subjected to this acceleration load.

Acceleration↗