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Biomedical subjects

R L Jones

Publications and source records attributed to R L Jones.

At least 325 records · Page 18Linked to original sources
PubMed1980

The effect of ionic strength on DNA-ligand unwinding angles for acridine and quinoline derivatives.

We have quantitatively examined the unwinding angles for the complexes of a related series of acridine and quinoline derivatives with DNA. Ethidium bromide was used as a control for determining superhelix densities at different ionic strengths. Relative to ethidium, 9-aminoacridine and quinacrine had an essentially constant unwinding angle of approximately 17 degrees at all ionic strengths tested. The apparent unwinding angle for chloroquine and 9-amino-1,2,3,4-tetrahydroacridine was found to be ionic strength dependent, increasing with increasing ionic strength. This suggests that competitive nonintercalative binding at low ionic strengths causes an apparent lowering of the quinoline unwinding angle. This can also explain why 4-aminoquinaldine, examined at low ionic strength, gives a quite low apparent unwinding angle. Quinacrine along with chloroquinine and 9-aminoacridine approaches a limiting value for their unwinding angle of approximately 17 degrees. 4-aminoquinaldine and 9-amino-1,2,3,4-tetrahydroacridine could not be examined at an ionic strength above 0.03 because of their very low equilibrium binding constants.

Aminacrine↗
PubMed1980

Low molecular weight iron-binding factor from mammalian tissue that potentiates bacterial growth.

A low molecular weight, iron-binding factor was isolated from horse liver. This host-associated iron transfer factor (HAITF) is capable of binding iron and stimulating bacterial growth by promoting iron uptake into bacteria. Also, when injected into infected animals, HAITF increases the virulence of bacterial infections. HAITF bioactivity is ubiquitous in animal tissues and present in serum. It is proposed that HAITF is a factor that inadvertently plays a role in the host-parasite competition for iron.

Animals↗
PubMed1980

Effects of sighs and different tidal volumes on compliance, functional residual capacity and arterial oxygen tension in normal and hypoxemic dogs.

In order to assess the usefulness of sighs in preventing deterioration of arterial PO2 (PaO2), functional residual capacity (FRC), and compliance in hypoxemic patients, the authors studied 20 anesthetized and paralyzed dogs. The dogs were ventilated with either normal (11.5 ml/kg) or large (23 ml/kg) tidal volumes and their lungs were either normal or made edematous with oleic acid injection. Sighs (46 ml/kg) were administered periodically and PaO2, FRC, and compliance were measured at intervals between sighs. In dogs with normal lungs, regardless of tidal volume, sighs produced a transient increase in compliance and FRC but PaO2 was not significantly affected. In dogs with pulmonary edema, sighs produced inconsistent effects on FRC and compliance and, interestingly, PaO2 decreased after the sighs may be unnecessary in patients with pulmonary edema, especially when they are already receiving large tidal volumes.

Animals↗
PubMed1980

Effect of cold on endogenous fucosyl transferase activity in corn roots.

Incubation of excised, 1-centimeter long root tips of corn in chilled distilled H(2)O increases the activity of extractable GDP fucose: polysaccharide fucosyl transferase. Enhancement of transferase activity is optimal at 10 C and incubation at this temperature for 8 hours causes a 3- to 5-fold stimulation of activity. Transfer of roots from 10 to 30 C reverses the enhancement of enzyme activity although reciprocal transfer of roots from 30 to 10 C does not stimulate the accumulation of transferase activity.

Journal Article↗
PubMed1980

Effect of temperature on the synthesis and secretion of alpha-amylase in barley aleurone layers.

The effect of temperature on alpha-amylase synthesis and secretion from barley (c.v. Himalaya) half-seeds and aleurone layers is reported. Barley half-seeds incubated at 15 C in gibberellic acid (GA) concentrations of 0.5 and 5 micromolar for 16 hours do not release alpha-amylase. Similarly, isolated aleurone layers of barley do not release alpha-amylase when incubated for 2 or 4 hours at temperatures of 15 C or below following 12 hours incubation at 25 C at GA concentrations from 50 nanomolar to 50 micromolar. There is an interaction between temperature and GA concentration for the process of alpha-amylase release from aleurone layers; thus, with increasing GA concentration, there is an increase in the Q(10) of this process. A thermal gradient bar was used to resolve the temperature at which the rate of alpha-amylase release changes; thermal discontinuity was observed between 19 and 21 C. The time course of the response of aleurone tissue to temperature was determined using a continuous monitoring apparatus. Results show that the effect of low temperature is detectable within minutes, whereas recovery from exposure to low temperature is also rapid. Although temperature has a marked effect on the amount of alpha-amylase released from isolated aleurone layers, it does not significantly affect the accumulation of alpha-amylase within the tissue. At all GA concentrations above 0.5 nanomolar, the level of extractable alpha-amylase is unaffected by temperatures between 10 and 28 C. It is concluded that the effect of temperature on alpha-amylase production from barley aleurone layers is primarily on the process of enzyme secretion.

Journal Article↗
PubMed1980

Effects of secondary polycythemia on cerebral blood flow in chronic obstructive pulmonary disease.

Cerebral blood flow was measured before and after venesection in 6 patients with chronic obstructive pulmonary disease and secondary polycythemia. The hematocrit was decreased from a mean of 59.6 to 43.9%, and whole blood viscosity was decreased by 35%. The supratentorial blood flow increased 78.2% (p < 0.005) after venesection; subtentorial flow also increased, but not significantly. The improvement in cerebral blood flow appeared to be related to a decrease in blood viscosity, because pulmonary function and arterial blood gases did not change significantly. There was subjective improvement in all patients, and this improvement might have been due to the increased supratentorial blood flow.

Aged↗
PubMed1980

Integrating the teaching of sickle cell anemia into the curriculum of the Cincinnati public school system.

In an effort to determine the impact of one aspect of the Cincinnati Comprehensive Sickle Cell Center's educational program, a study of the level of knowledge of sickle cell facts by elementary and secondary school students in the Cincinnati public school system was conducted. An underlying assumption of this study was that a specially adapted sickle cell teaching curriculum in conjunction with in-service training for science teachers by sickle cell education staff was effective and practical. The study provided support for this assumption and has important implications for educating the general public about sickle cell disease and sickle cell trait. This study was undertaken during the 1975-1976 school year, and has subsequently led to the adoption of this sickle cell teaching curriculum by the Cincinnati Board of Education.

Anemia, Sickle Cell↗
PubMed1979

Comparative viscometric analysis of the interaction of chloroquine and quinacrine with superhelical and sonicated DNA.

Unwinding angles for the structurally related antimalarial drugs chloroquine and quinacrine have been determined with superhelical Col E1 plasmid DNA by applying the quantitative method developed by Vinograd and co-workers (Revet, B.M., Schmir, M. and Vinograd, J. (1971) Nat. New Biol. 229, 10). The value for chloroquine, 8.6 degrees, calculated assuming an unwinding angle of 26 degrees for ethidium bromide, is significantly lower than the value for quinacrine, 22.5 degrees, calculated in the same manner. Viscometric titrations with sonicated calf thymus DNA were quantitated using available binding constants for the two drugs and indicated that chloroquine also causes significantly smaller DNA length increases on intercalation relative to quinacrine. The conclusion from these experiments is that chloroquine does not bind to DNA by the classical intercalation mechanism typical of quinacrine and ethidium.

Bacteriocin Plasmids↗
PubMed1979

Dimerization of coralyne and its propyl analogue and their association with DNA.

Dimerization of coralyne, Ia, and its propyl analogue Ic has been analyzed at neutral pH as a function of ionic strength. Even at low ionic strength (I = 0.02) dimerization constants (molar units) for both compounds are 10(5) or greater, which is considerably larger than values obtained for similar intercalating molecules. Coralyne seems to undergo association to higher aggregates somewhat easier than Ic, which could be due to the fact that the propyl group on Ic provides some steric hinderance in forming higher aggregates. Both compounds readily associate with DNA. At high ratios of ligand to DNA, the spectra for Ia or Ic are similar to that of a highly aggregated complex. At low ratios of ligand to DNA, the spectra for both compounds approach a limit, which is relatively independent of ionic strength and concentration, and can be identified with the intercalated species. The slight differences between Ia and Ic in dimerization or in association with DNA do not seem capable of explaining the significant differences in antileukemic activity of these compounds.

Antineoplastic Agents↗