Search PubMed⌕ Search

Biomedical subjects

L L Walker

Publications and source records attributed to L L Walker.

50 records · Page 3Linked to original sources
PubMed1977

Identification and Properties of the Messenger RNA Activity in Chlamydomonas reinhardi Coding for the Large Subunit of d-ribulose-1,5-bisphosphate Carboxylase.

Properties of the mRNA coding for the large subunit of ribulose-1,5-bisphosphate carboxylase from Chlamydomonas reinhardi were determined. Large subunit synthesis, directed by RNA from partially purified whole cell extracts, was detected by specific immunoprecipitation of polypeptide products synthesized in a heterologous translation system derived from Escherichia coli. Large subunit synthesis showed sharp RNA concentration dependence in an E. coli translation system, and at optimal RNA concentrations, immunoprecipitable large subunit synthesis accounted for 2% of the total incorporation. Large subunit messenger activity sedimented at 12 to 14S on nondenaturing sucrose gradients and did not bind to oligo(dT)-cellulose suggesting the mRNA is not polyadenylated. The immunoprecipitable products translated in vitro are not complete polypeptide chains, but are smaller peptides identifiable as large subunit fragments by tryptic fingerprint analysis. No immunoprecipitable product was obtained when similar RNA fractions were tested in a wheat germ translation system.

Journal Article↗
PubMed1977

Effect of levamisole on Mycobacterium leprae in mice.

Levamisole, an antihelminthic drug that is capable of enhancing immune responses in mice and in humans, was tested in experimental Mycobacterium leprae infections in mice by a number of schedules. Intermittent schedules were used, and administration of the drug was started (i) around the time of inoculation with M. leprae, (ii) when the M. leprae population was approaching the plateau level, (iii) after the onset of the plateau phase, or (iv) after BCG vaccination 28 days following the inoculation with M. leprae. No effect of drug could be discerned with any of the schedules.

Administration, Oral↗
PubMed1976

Informational complexity of the nuclear and chloroplast genomes of Chlamydomonas reinhardi.

DNA - DNA reassociation kinetics analyzed by hydroxylapatite chromatography have been used to determine the informational content of the Chlamydomonas reinhardi nuclear and chloroplast genomes. The kinetics indicate that nuclear DNA, with the exception of ribosomal cistrons, renatures as a single component with an informational complexity 25 times that of the Escherichia coli genome. The chloroplast genome has less than 0.3% of the informational complexity of the nuclear genome, but is present in about 50 copies in the vegetative cell. Chloroplast DNA shows about a 10-12% zero-time binding component.

Cell Nucleus↗
PubMed1976

Inpatient and emergency department utilization: the effect of distance, social class, age, sex, and marital status.

This study attempted to measure whether patients using two hospital services -- inpatient facilities and the emergency department -- were representative of the population. It sought to confirm the assumptions that, if patient demands were uniform and there were no barriers to emergency department use: (1) emergency patients would closely represent the population in the geographic service area of the hospital, and (2) factors such as distance from residence, age, marital status, social class, and sex, would be relatively uniform between inpatients and emergency patients. The first assumption was supported by the results of the study. Concerning the second, the 0- to 19-year-old group had a high emergency department utilization and low utilization of inpatient facilities when 35- to 65-year-old group had a lower emergency department and a higher inpatient usage pattern. The 65-year-old and over group had two and one-half times as many inpatient admissions as their number in the general service area would suggest. More men than women used the emergency department. Separated and divorced people were heavy users of the emergency department whereas widows heavily used inpatient facilities. Social class was not found to be significantly different among those using the inpatient service or emergency department.

Adolescent↗
PubMed1976

Immunity to Mycobacterium leprae infections in mice stimulated by M. leprae, BCG, and graft-versus-host reactions.

Infections of mice with Mycobacterium leprae in one rear foot pad immunized them against a second infection in the other rear foot pad. Purified bacilli harvested from the first infection also produced immuniy when injection into the foot pads of previously uninfected mice. Injections of BCG afforded similar protection, but had no adjuvant effect on M. leprae. M. duvali, a cultivable mycobacterium that is reported to be more closely related antigenically to M. leprae than BCG is, provided much less protection against M. leprae challenge than BCG did. Moreover, when M. duvali was mixed with BCG, it was not any more effective than BCG alone. Graft-versus-host reactions, induced by injections of parental spleen cells into F1 hybrids, provided no protection against M. tuberculosis and M. marinum challenge. They gave moderate protection against M. leprae in one experiment but not in another with a different schedule. Allogenic spleen cells had a protective effect when injected locally into the infected foot pad. The effect produced by these injections of spleen cells was a delay in the appearance of bacterial growth; however, there was no decrease in the rate of logarithmic growth when it did appear and no reduction in the eventual plateau level.

Animals↗
PubMed1972

Synthesis of DNA in toluene-treated Chlamydomonas reinhardi (DNA replication-chloroplast DNA-cell cycle-electron microscopy).

Toluene-treated Chlamydomonas reinhardi incorporate deoxynucleoside triphosphates (dNTPs) into DNA. Incorporation requires all four dNTPs, but requires neither ATP nor added DNA. The incorporation reaction is linear for nearly 20 min. The product of synthesis in treated cells is mainly chloroplast (beta-component) DNA. However, a small quantity of nuclear (alpha-component) DNA is also synthesized. Synchronously grown cells are most efficient in dNTP incorporation at a time in the cell cycle when chloroplast DNA is normally replicated. Toluene treatment disrupts the internal morphology of the cell, but leaves the outer membrane of the chloroplast intact.

Adenosine Triphosphate↗