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Biomedical subjects

K McCloskey

Publications and source records attributed to K McCloskey.

12 recordsLinked to original sources
PubMed2000

The use of magnetite-doped polymeric microspheres in calibrating cell tracking velocimetry.

Continuous magnetic separation, in which there is no accumulation of mass in the system, is an inherently dynamic process, requiring advanced knowledge of the separable species for optimal instrument operation. By determining cell magnetization in a well-defined field, we may predict the cell trajectory behavior in the well-characterized field environments of our continuous separators. Magnetization is determined by tracking the migration of particles with a technique known as cell tracking velocimetry (CTV). The validation of CTV requires calibration against an external standard. Furthermore, such a standard, devoid of the variations and instabilities of biological systems, is needed to reference the method against day-to-day shifts or trends. To this end, a method of synthesizing monodisperse, magnetite-doped polymeric microspheres has been developed. Five sets of microspheres differing in their content of magnetite, and each of approximately 2.7 microm diameter, are investigated. An average gradient of 0.18 T/mm induces magnetic microsphere velocities ranging from 0.45 to 420 microns/s in the CTV device. The velocities enable calculation of the microsphere magnetization. Magnetometer measurements permit the determination of magnetization at a flux density comparable to that of the CTV magnet's analysis region, 1.57 T. A comparison of the results of the CTV and magnetometer measurements shows good agreement.

Cells, Cultured↗
PubMed1999

Quantification of cellular properties from external fields and resulting induced velocity: cellular hydrodynamic diameter.

An experimental technique is discussed in which the size distribution of a population of cells is determined by calculating each cell's settling velocity. The settling velocity is determined from microscopically obtained images which were recorded on SVHS tape. These images are then computer imaged and processed, and the cell's location and velocity are determined using a computer algorithm referred to as cell tracking velocimetry (CTV). Experimental data is presented comparing the distribution of human lymphocytes and a human breast cancer cell line, MCF-7, determined using a Coulter counter and the CTV approach.

Algorithms↗
PubMed1999

Quantification of cellular properties from external fields and resulting induced velocity: magnetic susceptibility.

An experimental technique is discussed in which the magnetic susceptibility of immunomagnetically labeled cells can be determined on a cell-by-cell basis. This technique is based on determining the magnetically induced velocity that an immunomagnetically labeled cell has in a well-defined magnetic energy gradient. This velocity is determined through the use of video recordings of microscopic images of cells moving in the magnetic energy gradient. These video images are then computer digitized and processed using a computer algorithm, cell tracking velocimetry, which allows larger numbers (>10(3)) of cells to be analyzed.

Cells, Cultured↗
PubMed1995

Evaluation of integrated night vision goggle (NVG) helmets under sustained +Gz.

Three integrated night vision goggle (NVG) helmets from different manufacturers were evaluated under high-G conditions. Structural and operational integrity, as well as neck forces in pounds, were determined via instrumented manikin testing before human exposure with the helmets during sustained +Gz. Results of the manikin testing showed that the helmets could withstand the rigors of high-G, and that predicted forces (using helmet weights and centers-of-gravity) matched those obtained experimentally from load cells in the x-axis of the manikin's neck. After manikin testing, 10 subjects were randomly exposed to four different high-G profiles on the Dynamic Environmental Simulator (DES) man-rated centrifuge located at Wright-Patterson AFB, OH: gradual onset to +8 Gz, a simulated aerial combat maneuver (SACM) profile, and two +4 Gz profiles, one with the mask dangling from the helmet and the other with the mask removed. Fit assessments were conducted before high-G exposure, and one helmet was affected significantly by failure of fit. The degree of migration of the NVG intensified image away from the eyes was affected most by the following helmet characteristics: design of the nape strap, size of the NVG image provided by each helmet system, goodness of helmet fit, and the use of the mask as a stabilizer. Although neck strength of each subject was measured and compared to the degree of head stability while wearing each helmet, no effects were found. However, subjects were not allowed to perform fast, high-amplitude head movements in the centrifuge for safety reasons.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Ethics in human experimentation: examples in aeromedical research.

The existence of ethical standards directing how humans are utilized in clinical and human-use research have a significant impact on the conduct and outcome of aeromedical research. The validity of the data generated by human research is a direct result of the application of these ethical guidelines. The risk/benefit ratio evaluation can terminate a project even before its initiation. New technology, individual beliefs, and a changing society will continue to guarantee controversy over how human subjects should be screened and evaluated as well as how research should utilize them. Ethical guidelines are not cast in stone. Their interpretation is influenced by new experimental results, the individual researcher, the intended subject, the composition of human use committees, and the social environment. How we address new and old concerns alike will dictate the research environment of the future.

Aerospace Medicine↗
PubMed1995

Ethics in human experimentation: historical perspectives.

Ethics has received renewed attention recently as evidenced by recent revelations of experimentation on Eskimos during the 1950s and a new President vowing to raise ethical standards of conduct within government. There is also an ongoing, intense scrutiny of past radiation-exposure experiments with all of its possible ethical violations. This paper is a modest attempt to familiarize the reader with some of the historical development of ethics in human-use research. Debate concerning the use of humans as subjects of medical and behavioral experimentation has a long and distinguished history going back at least 2,000 years. A short historical review reveals that ethical behavior exhibits a pendulum action between the extremes of protection of humans at all costs and the attainment of scientific knowledge at all costs. Only by knowing the historical foundation of ethics can one understand the current issues surrounding human experimentation.

Ethics, Medical↗
PubMed1993

Individual differences and subgroups within populations: the shopping bag approach.

The aerospace medical research community needs to consider the individual as something other than a statistical entity. The cumulative effects of performance enhancers that are collectively ignored, secondary to statistical analysis of populations, can be significant for individuals. By considering the individual, all aspects of whatever makes humans unique need to be integrated into research. One suggested remedy to the problem of subordination of the individual to the population mean/standard deviation is the use of a "shopping bag" approach. In this approach, each individual may select those performance enhancers that work best for him or her (based on controlled studies). Acceleration protection devices are used as an example. The impact of this philosophy can be readily seen in human factor design strategy as well as in the interpretation of human research data.

Aerospace Medicine↗
PubMed1991

Pediatric interhospital critical care transport: consensus of a national leadership conference.

As pediatric interhospital critical care transport has evolved toward a distinct discipline, practitioners in this field have recognized the need for guidelines for transport program development and patient care. At a gathering of medical directors of pediatric transport programs, the following topics were discussed: team composition and transport staffing, training requirements for pediatric and nonpediatric transport teams, goals and design of a transport data base, and medical-legal issues, including the responsibilities of the referring and receiving institutions. Consensus recommendations were made for the major issues in each of these areas. Several questions were raised which may be answered by multiinstitutional studies.

Child↗
PubMed1989

A study of techniques for the distribution of oral rabies vaccine to wild raccoon populations.

This study evaluates a technique for delivering an oral rabies vaccine to wild raccoon (Procyon lotor) populations. Various baits and attractants were first tested on caged raccoons and baiting trials were then conducted in two distinct physiographic regions of Virginia (USA), the coastal plain and the Piedmont plateau. Raccoon population density studies preceded the field trials. Each polyurethane sponge bait distributed contained approximately 200 mg tetracycline as a tissue biomarker, and was presented in an outer bag with a fish-based attractant. Baits were frozen until used and distributed from an aeroplane throughout two 4-km2 sites in each region. One site received 450 baits/km2 and the other 120 baits/km2. Postbaiting evaluation included the direct observation of baits in the field and the examination of teeth and bone from trapped and hunted animals for evidence of the biomarker. Between 30% and 73% of the captured animals showed evidence of bait consumption. The proportion of animals with evidence of bait uptake changed when areas adjacent to the actual baiting site were included. The percentage of animals taking baits was not related to the density of baits that were distributed.

Administration, Oral↗
PubMed1981

Tryptophan metabolism in children with attentional deficit disorder.

The authors present the first report, to their knowledge, of hyperserotonemia in children with attentional deficit disorder who had normal intelligence. Hyperserotonemic children had significantly lower levels of plasma total and protein-bound tryptophan and a higher percentage of free tryptophan than those with normal serotonin levels. Plasma kynurenine did not differ, suggesting that the hyperserotonemia is not due to a blockade of the kynurenine pathway but may reflect on increase in tissue tryptophan uptake and use.

Adolescent↗