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Biomedical subjects

C W Johnson

Publications and source records attributed to C W Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1992

The recording and analysis of EMG and jaw tracking. I. The recording procedure.

A computer-based system is described which records and analyses electromyographic (EMG) signals and tracking data for mandibular movements during function. EMG signals were obtained bilaterally from six muscles and a Sirognathograph monitored the position of the lower incisor teeth in three dimensions. Directed jaw movement tasks by subjects were monitored. These data were continuously sampled at a rate of 1 KHz per channel over an operator controlled period. Analysis of the data was performed off-line following the experiment. Individual chewing cycles associated with masticatory function were identified and the timing and dimensions of each chewing envelope established. Corresponding EMG values were also determined and displays of EMG and jaw movement were plotted on a common time base. An average chewing cycle and correlated EMG activity could also be displayed on a high resolution monitor and plotted for a hard copy to enable a comparison to be made between subjects with and without jaw dysfunction.

Analysis of Variance↗
PubMed1991

Acute pulmonary emboli associated with guidewire change of a central venous catheter.

The potential complications of percutaneous venous catheterizations are many and include pneumothorax, subclavian and carotid artery puncture, hematoma, air embolism, catheter malposition, catheter fragment embolization, venous thrombosis and infection. This case report describes a patient who developed angiographically documented pulmonary emboli associated with the changing of a central venous catheter over a guidewire using Seldinger technique. This episode adds the possibility of acute pulmonary emboli to the list of potential complications from central venous catheterizations.

Acute Disease↗
PubMed1990

Distinct and non-cross-reactive epitopes are recognized on B16 melanoma by LAK cells and anti-B16 monoclonal antibodies.

Two rat anti-B16 melanoma monoclonal antibodies (MoAb), designated IB16-6 and IB16-8, recognize an epitope expressed with high density on the surface of B16 parental cells and B16-F1, F10, F10FLR, and BL6 sublines. The purpose of this study was to define by means of cytolytic and clonogenic assays whether these MoAbs reacted with the same or distinct determinants as those recognized on B16 targets by lymphokine-activated killer (LAK) cells. Using 125I-labeled antibody and Scatchard analysis, the affinity constant (KA) of IB16-6 was determined to range from 5.6 to 9.4 x 10(8) liter/M and the number of receptor sites per B16 cell was 4.8 x 10(4) to 2.5 x 10(5). The effects of anti-B16 MoAb on LAK activity were determined by either preincubating 51Cr-labeled B16 target cells with varying concentrations of MoAb, followed by the cytolytic assay, or exposing unlabeled B16 cells to MoAb, and then carrying out a 10-day clonogenic assay. Over a wide range of antibody concentrations, IB16-6 and IB16-8 had minimal effects on LAK activity, and even at MoAb concentrations up to 1 mg there were no changes in target cell sensitivity or colony-forming ability. Enzymatic treatment of B16 melanoma cells with either trypsin or pronase completely removed the epitope recognized by MoAb IB16-6 but did not alter B16 sensitivity to LAK cells. These observations indicate that the LAK recognition unit was distinct from the epitope reactive with MoAb IB16-6 and that the B16 determinant(s) recognized by LAK cells is resistant to proteolytic enzymes. The molecular structure of each of these remains to be determined.

Animals↗
PubMed1988

Ultrastructure of junctional epidermolysis bullosa in Belgian foals.

Ultrastructural examination of a mechanobullous disease of probable hereditary nature in Belgian foals, confirmed light microscopic findings that separation of the dermo-epidermal junction occurred through the lamina lucida of the basement membrane, leaving the intact lamina densa adherent to the dermis and the plasmalemma of the basal epithelial cells intact. The location of the cleft and the presence of small hemidesmosomes in adjacent intact skin are additional characteristics which make this condition similar to junctional epidermolysis bullosa of man.

Animals↗
PubMed1987

Phenotypic diversity of murine B16 melanoma detected by anti-B16 monoclonal antibodies.

A panel of monoclonal antibodies (MoAbs), produced against the murine B16 melanoma, has been used to characterize its phenotypic diversity. Six MoAbs that did not bind to primary cultures of kidney, brain or liver, spleen cells, thymocytes, 3T3 fibroblasts, melanin, or transferrin receptors were selected for further evaluation. Five MoAbs, which recognized surface antigens expressed on parental B16 cells and the B16-F1, B16-F10, B16-F10 FLR, and B16-BL6 sublines, did not appear to cross-react with each other, suggesting that they identified antigenically distinct epitopes. Four MoAbs, designated as IB16-2, IB16-4, IB16-8, and IB16-10, recognized B16 surface antigens that were variably expressed over short periods of time. This variable expression was independent of the cell cycle and was characteristic of four B16 sublines. Two of these MoAbs, both of the IgG2b isotype, fixed rabbit and guinea pig complement and were cytolytic in the presence of rabbit complement. One MoAb, designated IB16-6, recognized a surface antigen consistently expressed on greater than 90% of cells of both the parental tumor and the sublines. This MoAb bound to several murine and one human melanoma cell line, but not to other histopathological types of tumors or normal tissues. The cellular antigen that this antibody recognized was not detected in the cytoplasm, did not modulate in the presence of IB16-6, and was sensitive to trypsin, pronase, alcohols, acetone, and detergents, thereby suggesting that it was a protein. Our data are among the first that directly show the extent of phenotypic diversity of the B16 melanoma and sublines that have been derived from it.

Animals↗
PubMed1987

Nutritional intake from food sources of high school football athletes.

Male high school football athletes served as subjects (no. = 134; age = 15.0 +/- 1.2 years, range = 12 to 18 years; weight = 67.7 +/- 13.9 kg) (mean +/- standard deviation) in a dietary survey project to characterize nutritional intake from food sources. Dietary intake data were collected using the recall method for 1 weekday during the summer when athletes participated in unsupervised, informal conditioning. Subjects were grouped by age as junior high (JR-HI: 12 to 14 years) or senior high (SR-HI: 15 to 18 years) students. Absolute mean energy and nutrient intakes, except for vitamin A, were statistically greater for SR-HI relative to JR-HI (p less than .02). These findings are consistent with age-related growth on nutritional intake. Mean nutritional intakes from food sources for SR-HI met or exceeded the RDAs. For JR-HI, mean intakes met or exceeded the RDAs except for energy (94% RDA) and zinc (87% RDA). Mean intakes exceeded those of a representative sample of same-age boys in the larger American population.

Adolescent↗
PubMed1985

Monoclonal antibodies directed against preneoplastic and neoplastic murine mammary lesions.

We have produced a panel of monoclonal antibodies directed against a dimethylbenzanthracene-induced murine mammary tumor. Five rat-mouse hybridomas produced antibodies that bound to some murine mammary tumors, but not to normal renal adherent cells, lymphocytes, 3T3 fibroblasts, red blood cells, or mammary gland. One of these antibodies, designated AMT8, was selected for further evaluation based on its relatively strong reactivity, as determined by immunofluorescence. Indirect immunofluorescent studies on frozen histological tissue sections and quantitative immunofluorescent binding studies on cultured normal and tumor cells revealed that AMT8 was bound to certain murine mammary tumors and their preneoplastic hyperplastic nodules, but not to normal murine organs including normal mammary glands. Two tumors and their hyperplastic alveolar nodule counterparts that contained the antigen recognized by AMT8 did not express functional estrogen and progesterone receptors, indicating that antigen expression was not dependent on functional receptors. The antigen recognized did not cap, was found to modulate slowly, and was reexpressed in the presence of excess AMT8. From these findings, we conclude that AMT8 may prove to be a valuable tool for the study of early mammary tumorigenesis.

Animals↗
PubMed1984

Injection of cells and monoclonal antibodies into mice: comparison of tail vein and retroorbital routes.

Organ distribution and blood concentration profiles were compared following injection of mice with radiolabeled test agents via the lateral tail vein or retroorbital venous sinus. Monoclonal antibodies directed against B16 melanoma of C57BL/6 origin were labeled with iodine-125. Thymocytes from BALB/c mice and B16 melanoma cells were labeled with technetium-99m sodium pertechnetate (Na 99mTcO4). Animals were injected with 5 microCI of iodinated antibody, 5 X 10(5) syngeneic thymocytes, 2.5 X 10(5) melanoma cells, or 10 microCi Na 99mTcO4 in 0.2 ml saline via either route. In non-tumor-bearing C57BL/6 mice radiolabeled monoclonal antibody was found primarily in the gastrointestinal tract, liver, and blood. Na 99mTcO4 localized in the gastrointestinal tract, 99mTc-labeled thymocytes in the spleen and liver, and 99mTc-labeled B16 melanoma cells in the liver and lungs. Pharmacokinetic analysis of blood samples taken 4, 8, and 12 min following injection of the labeled agents suggested that the iodinated antibody had less vascular permeability than Na 99mTcO4 and that thymocytes and B16 melanoma cells were trapped in the pulmonary vasculature as they passed through the lungs. It is noteworthy that no biologically significant differences in organ distribution patterns or blood decay profiles were found between lateral tail vein and retroorbital routes. The data clearly indicate that these routes can be used interchangeably with one another for intravenous injections.

Animals↗
PubMed1983

Esophageal food impaction: treatment with glucagon.

Nineteen patients who had foreign bodies in the distal esophagus were examined prospectively to determine the efficacy of intravenous glucagon in relieving the obstruction. The administration of glucagon resulted in clearance of the impacted food in seven patients. Although the success rate is relatively low, the risk is minimal and justifiable. Use of intravenous glucagon is a safe, worthwhile initial step in the treatment of distal esophageal foreign bodies.

Adult↗