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Biomedical subjects

J L Walker

Publications and source records attributed to J L Walker.

At least 127 records · Page 7Linked to original sources
PubMed1977

Time estimation and total subjective time.

Techniques for estimation of magnitude were used in a questionnaire given to 100 university students to test the hypothesis that the subjective duration of an interval of actual time decreases in proportion to total subjective time rather than total chronological age. The results supported the subjective time hypothesis for retrospective reports of perceived duration of a year at both one-half and one-quarter of the subject's present age. In both cases the subjective time hypothesis provided a better fit to the data than the chronological age model. The hypothesis of the subjective time model that subjective life-span is equal to the square root of the statistically expected life-span was also tested but was not confirmed.

Adult↗
PubMed1975

Intracellular chloride activity in frog heart.

1. Chloride liquid ion exchanger micro-electrodes have been used to measure intracellular chloride activity (aiCl) in isolated pieces of frog sinus venosus, atrium and ventricle. 2. aiCl was found to be 35-0 +/- 3-2, 17-3 +/- 0-8 and 17-6 +/- 0-8 mM in sinus venosus, atrium and ventricle, respectively. 3. In atrium and ventricle aiCl is independent of whether the tissue is beating or non-beating. 4. In non-beating ventricle aiCl changes rapidly and reversibly when aOCl is reduced by replacing chloride with glucuronate. 5. ECl calculated from the measured aiCl has been compared with ECl calculated from the constant field equation assuming either constant chloride conductance or constant chloride permeability. 6. It is suggested that chloride is actively transported into the cells in all three kinds of frog heart tissue.

Animals↗
PubMed1973

The release of spasmogenic substances from human chopped lung tissue and its inhibition.

1. Human lung tissue, passively sensitized with reaginic antibodies, released prostaglandins E(1), E(2) and F(2alpha) in addition to histamine and slow reacting substance (SRS-A), when exposed to the appropriate antigen. No rabbit aorta contracting substance (RCS) was detected.2. Experiments with rats and guinea-pigs showed that the release of RCS is not confined to anaphylactic reactions mediated by non-reaginic antibodies but may be a feature of anaphylaxis in guinea-pigs alone.3. Human lung tissue gently agitated with a blunt nylon rod liberated an E-type prostaglandin and RCS in addition to histamine and SRS-A.4. Human isolated bronchial muscle was contracted by RCS.5. Disodium cromoglycate antagonized the release of prostaglandins during anaphylaxis but not during agitation of human lung tissue, whereas indomethacin blocked the release of prostaglandins during agitation and anaphylaxis.6. The release of an E-type prostaglandin during anaphylaxis in human lung tissue, which inhibits the further release of histamine could be another example of the regulatory role of prostaglandins in body functions.

Anaphylaxis↗
PubMed1972

The transient response and impedance locus of a mobile site membrane.

The kinetic properties of a mobile site membrane are analyzed theoretically and the results are compared with experimental data obtained from a simple model system. In the model system the measured response to a step change in electric current is a single relaxation process, in excellent agreement with the theoretically predicted behavior. To this relaxation process corresponds an anomalous capacitance whose properties are obtained by performing a frequency analysis of the system. By plotting the impedance locus of this mobile site membrane, the locus is shown to exhibit a 45 degrees phase angle at high frequencies, a phenomenon which is generally associated with depletion layers.

Binding Sites↗
PubMed1972

Synthesis of Epstein-Barr virus after activation of the viral genome in a "virus-negative" human lymphoblastoid cell (Raji) made resistant to 5-bromodeoxyuridine (thymidine kinase-virus antigen-immunofluorescence-herpesvirus fingerprints).

The Raji line of human lymphoblastoid cells, which does not show expression of Epstein-Barr virus, was made resistant to 5-bromodeoxyuridine. Within several weeks after removal of the drug, Epstein-Barr virus particles were detected in the cells. The sequence of virus appearance in the 5-bromodeoxyuridine-resistant cells indicated drug-induced activation of a repressed Epstein-Barr virus genome.

Animals↗
PubMed1971

Persistence of a repressed Epstein-Barr virus genome in Burkitt lymphoma cells made resistant to 5-bromodeoxyuridine.

The P3HR-1 line of human lymphoblastoid cells that is Epstein-Barr virus positive was made resistant to 5-bromodeoxyuridine. Epstein-Barr virus-associated antigens, but not virus particles, were produced in P3HR-1(BU) cells maintained on 5-bromodeoxyuridine. However, virus particles did appear within 4 days after removal of the drug. Thymidine kinase activity was limited to P3HR-1(BU) cells producing viral antigen, whereas all control P3HR-1 cells showed thymidine kinase activity regardless of viral antigen synthesis. Cellular DNA in most P3HR-1(BU) cells was made via pathways that did not involve thymidine kinase. In cells having a pathway that involved thymidine kinase, a second DNA of density 1.71 g/cm(3), corresponding to Epstein-Barr virus, was detected.IT WAS CONCLUDED THAT: (a) a repressed Epstein-Barr virus genome persists in P3HR-1(BU) cells that do not contain thymidine kinase, with activation of the viral genome being accompanied by productive infection and the appearance of enzyme, and (b) thymidine kinase activity in P3HR-1(BU) cells could be used as a marker for viral genome expression.

Animals↗