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Biomedical subjects

C P Mason

Publications and source records attributed to C P Mason.

8 recordsLinked to original sources
PubMed1995

The VA-Cyberware lower limb prosthetics-orthotics optical laser digitizer.

Characterization of the residual limbs and limb segments of patients for prosthesis and orthosis design has principally been a subjective process, highly dependent upon the skill, level of training, and experience of the prosthetist/orthotist involved. Even with the application of computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies in prosthetics and orthotics, residual limb/limb segment characterization has remained substantially subjective and dependent upon prosthetist/orthotist skill, training, and experience. To eliminate the variations and errors that frequently occur because of this dependence, and to further quantify the patient measurement process, rehabilitation engineering researchers at the New York Department of Veterans Affairs Medical Center developed an optical laser digitizer for quantitative characterization of patients' residual limbs'/limb segments' spatial geometry and surface topography. The optical digitizer developed is described, and results of laboratory and clinical tests with the digitizer are presented. Examples showing the capability of the digitizer to accurately, rapidly, repeatably, and consistently capture the contours over the entire surfaces of the residual limbs of patients with below-knee (BK) and above-knee (AK) amputation, the lower limbs of orthotics patients, and the feet and ankles of pedorthics patients, are given. In addition, results of a comparative clinical study of optical digitization and standard prosthetics CAD plaster wrap cast electromechanical digitization of the residual limbs of subjects with BK and AK amputation are presented. The enhanced accuracy, repeatability, and consistency afforded by optical digitization are shown. Finally, areas for refinement of the optical digitizer's design, identified in the project's laboratory and clinical tests, are discussed.

Amputation Stumps↗
PubMed1992

Automated fabrication of mobility aids (AFMA): below-knee CASD/CAM testing and evaluation program results.

In 1988 the Department of Veterans Affairs Rehabilitation Research and Development Service, under the directorship of Margaret J. Giannini, M.D., began a nationally directed computer-aided design and computer-aided manufacturing (CAD/CAM) research program for the Automated Fabrication of Mobility Aids (AFMA). Under this program CAD/CAM research and development centers were established at the Prosthetics Research Study in Seattle, WA; at Northwestern University and the VA Lakeside Medical Center in Chicago, IL; and at the VA Medical Center and New York University Medical Center in New York, NY. These three centers conducted a collaborative program: (a) to introduce CAD/CAM technologies to prosthetists, physicians, therapists, and rehabilitation health care professionals in the United States; (b) to evaluate the feasibility of using CAD/CAM systems in clinical prosthetics settings; (c) to test and evaluate the University College London-Bioengineering Center's and the University of British Columbia-Medical Engineering Resource Unit's respective systems for the computer-aided design and computer-aided manufacture of prosthetic sockets (CASD/CAM) for below-knee amputees; and, (d) to obtain quantitative data for refinement of the CASD/CAM systems tested, and for the development of new, enhanced, more efficacious, and expedient systems.

Adult↗
PubMed1989

Nonlinear muscle recruitment during intramuscular and nerve stimulation.

Future progress in neuromuscular prostheses will depend on developing techniques for stimulating paralyzed muscle, especially utilizing neuromuscular stimulation. We have found nonlinear force versus stimulus amplitude characteristic (recruitment) curves in the gastrocnemius-soleus-plantaris muscle group of the cat in response to stimulation of the tibial nerve near the muscle entry point. Such response characteristics are undesirable in neuromuscular control systems. Nonlinear recruitment curves usually consisted of two regions in which force increased linearly with stimulus amplitude, separated by a "plateau" region in which force was relatively constant. The two linear regions were associated with activation of separate neuromuscular compartments (lateral or medial gastrocnemius, plantaris, soleus, or subdivisions of those muscles). When the stimulated myoelectric responses from these compartments were plotted versus stimulus amplitude, the region of recruitment between threshold and saturation often did not appreciably overlap for different compartments, suggesting that the axons innervating those compartments were physically segregated within the nerve from axons innervating other compartments. Correlation coefficients between force and stimulated myoelectric response were very high (up to R2 = 0.99) when using a composite curve produced by averaging myoelectric response curves recorded from each of the active compartments. By dividing the tibial nerve into its component bundles or fascicles and stimulating each in turn, it was possible to show that individual bundles innervate non-overlapping groups of muscle compartments, and that recruitment of the nerve bundles over different threshold ranges could account for the nonlinear force/stimulus response curves initially observed. The presence of separate innervation of muscles or compartments by fascicles should be an important factor in designing functional neuromuscular stimulation (FNS) systems.

Animals↗
PubMed1982

Isolation of chlorine-containing antibiotic from the freshwater cyanobacterium Scytonema hofmanni.

Scytonema hofmanni, a filamentous freshwater cyanobacterium (blue-green alga), produces secondary metabolites which inhibit the growth of other cyanobacteria and green algae. A rapid, qualitative assay for this inhibition has been developed with Synechococcus as the test organism. This assay procedure has led to the isolation and characterization of an antibiotic (named cyanobacterin) from Scytonema. The antibiotic has a molecular weight of 430 and an empirical formula of C23H23O6Cl and contains a gamma-lactone and a chlorinated aromatic nucleus. It inhibits the growth of various algae but has limited effect on nonphotosynthetic bacteria or protozoans and thus may have potential use as a specific algicide.

4-Butyrolactone↗
PubMed1979

Histological staining of hepatitis B antigen in paraffin embedded liver tissue.

Two hundred and six unselected liver biopsies were stained with Gomori's aldehyde fuschin, aldehyde thionine, and a modified orcein stain, according to Shikata and others (1974). Six cases showed positive cytoplasmatic staining indicative of hepatitis B antigen. It is suggested that one of these methods should be used in the study of liver biopsies, as an additional tool in the detection of hepatitis B carriers.

Hepatitis B Antigens↗