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Biomedical subjects

J W Moore

Publications and source records attributed to J W Moore.

At least 199 records · Page 11Linked to original sources
PubMed1981

Use of simple tasks to test for impairment of complex skills by a sedative.

Examination of the effect of three doses of pentobarbital on the comparative performance of a complex psychomotor task with two simple neuromotor tasks, i. e., standing steady and pendulum eye tracking, revealed a high correlation. These simple tasks could be used as measures of intoxication since they do not require extensive training. Examination of the complex task impairment blood level ratio revealed that impairment relative to blood level was much greater in the absorption phase. This changing ratio underscores the point that blood levels alone are not an adequate estimate of intoxication.

Adult↗
PubMed1981

Influence of water movements and other factors on distribution and transport of heavy metals in a shallow bay (Canada).

Concentrations of heavy metals and cyanide in water and sediments were determined from December 1974 to February 1976 in Yellowknife Bay situated in northern Canada. The bay receives a continuous discharge of liquid waste effluents from an operating gold mine. Arsenic reached a maximum concentration of 3100 mg kg(-1) in sediments near the waste source and decreased to minimum of less than 12 mg kg(-1) moving away from this area; corresponding ranges for Pb, Cu, Zn, Hg, and Fe were 13-800 mg kg(-1), 45-785 mg kg(-1), 23-935 mg kg(-1) 35-505 mg kg(-1) and 1.9-6.3% respectively. Although most pollutants were recorded at low levels in the water, arsenic and copper rose to 0.75 and 0.29 mg L(-1) coincident with maximum discharge from the waste source. Overall, water movement (generated by inflowing rivers and wind) was the most important factor governing the distribution of metals in the bay. Although surrounding islands also restricted the movement of pollutants through the bay, water depth, slope of the bottom and organic content of the substrate did not have a measurable impact on concentrations in sediments.

Canada↗
PubMed1981

Distribution of heavy metals and radionuclides in sediments, water, and fish in an area of Great Bear Lake contaminated with mine wastes.

The concentrations of heavy metals and radionuclides in the sediments and water of Great Bear Lake were determined during 1978 near an operating silver mine and an abandoned uranium mine. Additional information on the level of mercury in fish tissues were also collected. The mines, situated on the same site, deposited tailings and other waste material directly into the lake. The concentrations of mercury, lead, manganese, and nickel in the sediments were highest near the tailings deposit and decreased significantly as the distance from the mine increased. Although there were also significant positive correlations between these metals and the organic content of the sediments, water depth and slope of the bottom had no impact on metal distribution. Since the concentrations of arsenic, cobalt, copper, 226radium, 210lead and 230thorium varied inconsistently throughout the study area, the distribution of these substances could not be related to any of the environmental factors that were measured. There were, however, significant negative correlations between the concentrations of 232thorium and 228thorium and distance from the mine and organic content of the sediments. Heavy metal and radionuclide levels in water were generally below detectable limits, reflecting the strong chemical bonding characteristics of the sediments. The low concentrations of mercury in the tissues of lake trout Salvelinus namaycush were probably related to low uptake rates and the ability of this species to move into uncontaminated areas of the lake.

Animals↗
PubMed1981

Dynamics of potassium ion currents in squid axon membrane. A re-examination.

The original experiments of Cole and Moore (1960. Biophys. J. 1:161-202.), using conditioning and test membrane potentials to examine the dynamics of the potassium channel conductance in the squid axon, have been extended to test voltage levels by the use of tetrodotoxin to block the sodium conductance. The potassium currents for test voltage levels from -20 to +85 mV were superposable by translation along the time axis for all conditions tested: (a) with depolarizing conditioning voltages; (b) with hyperpolarizing conditioning voltages; and (c) in normal and in high potassium external media. The only deviations from superposition seen were when the internal sodium concentration was abnormally high and the potassium currents showed saturation at high levels of depolarization. Some restoration toward normal kinetics could be obtained by rapidly repeated depolarizations.

Animals↗
PubMed1981

Potassium ion currents in the crayfish giant axon. Dynamic characteristics.

The kinetics of the voltage-sensitive potassium channel in crayfish axon have been examined. The conductance increase after a step depolarization from rest can be described by a first-order kinetic process raised to the third power. When conditioning voltage levels preceded the test pulse, the steady-state conductance was found to be independent of initial conditions. Depolarizing conditioning voltages in general allowed superposition of test voltage potassium currents by a shift along the time axis. Hyperpolarizing conditioning voltages produced a delay in onset of conductance during the test pulse and changed the kinetics so that superposition was not possible. The delay increased during the hyperpolarization with a first-order lag having a time constant in the range of 1.5-3 ms. Return to the resting level caused recovery from the delayed state to follow a single exponential decay with a time constant of 1.9-2.2 ms. The steady state delay vs. voltage curves were not saturated at potentials as negative as -180 mV.

Animals↗
PubMed1980

Conditioned inhibition of the nictitating membrane response in decorticate rabbits.

Rabbits with substantial neocortical ablation were trained in a Pavlovian conditioned inhibition task using a light as the reinforced conditioned stimulus (CS) and the same light compounded with a tone as the non-reinforced CS. The conditioned response was the nictitating membrane response, and the unconditioned stimulus was paraorbital shock. Training began 4-14 months postoperatively. With a number of procedural variations across 4 experiments, there was little evidence of impaired conditioned inhibition by decorticates compared to control animals. These results are consistent with earlier reports on Pavlovian discrimination learning and reversal involving single-element CSs from different sense modalities. Hence, they extend the basic conclusion that neocortex is not essential for Pavlovian inhibition to the conditioned inhibition paradigm. Consideration of these findings in the light of previous investigations of conditioned inhibition in rabbits, involving mesencephalic or hippocampal lesions, supports the hypothesis that the crucial neural elements for Pavlovian inhibition may be located in the brain stem.

Animals↗
PubMed1980

Effects of cellular geometry on current flow during a propagated action potential.

An impulse propagating in a cell with nonuniform geometry sees an increased electrical load at regions of increasing diameter or at branch points with certain morphologies. We present here theoretical and experimental studies on the changes in membrane current and axial current associated with diameter changes. The theoretical studies were done with numerical solutions for cable equations that were generalized to include a varying diameter; the Hodgkin-Huxley equations were used to represent the membrane properties. The experimental studied were done using squid axons with the axial insertion of platinized platinum wires to create a localized region of increased electrical load. As an action potential approaches a region of increased electrical load, the action potential amplitude and rate of rise decrease, but there is a marked increase in the magnitude of the inward sodium current. The time integrals of the inward and outward currents are not constant along the fiber and indicate net inward charge movement at regions subjected to an increased electrical load. Changes in the waveform of the axial current at such a region help to explain the temperature dependence of propagation failure at regions of increasing electrical load.

Action Potentials↗
PubMed1980

Genetics of the buttercup plumage pattern.

Genetic analysis of the Buttercup breed of chickens indicates that they carry the buttercup allele (ebc) at the E locus, modified by the columbian-like primary pattern mutation Db and a secondary pattern gene resulting in autosomal barring. The interactions between ebc and the Db alleles are clarified by both F2 and testcross data. Homozygous ebc in the absence of Db results in a modified stripe pattern, whereas the light parallel back stripes are irregular and wider than those of wild type chicks. The dorsal head stripe is also broken and irregular, while the ground color is of a lighter shade of tan. Adult ebc/ebc db+/db+ males are typical black-breasted wild types as suggested previously by Brumbaugh and Hollander (1965). Adult females closely resemble the brown (eb/eb) phenotype. Further proof that the buttercup gene is an allele at the E locus is provided by F2 segregation data for crosses between Buttercup (ebc/cbc db+/db+) and Light Brown Leghorns (e+/e+ db+/db+) and Black Langshans (E/Edb+/db+).

Animals↗
PubMed1979

Propagation of action potentials in squid giant axons. Repetitive firing at regions of membrane inhomogeneities.

Effects of reduction in potassium conductance on impulse conduction were studied in squid giant axons. Internal perfusion of axons with tetraethylammonium (TEA) ions reduces G K and causes the duration of action potential to be increased up to 300 ms. This prolongation of action potentials does not change their conduction velocity. The shape of these propagating action potentials is similar to membrane action potentials in TEA. Axons with regions of differing membrane potassium conductances are obtained by perfusing the axon trunk and one of its two main branches with TEA after the second branch has been filled with normal perfusing solution. Although the latter is initially free of TEA, this ion diffuses in slowly. Up until a large amount of TEA has diffused into the second branch, action potentials in the two branches have very different durations. During this period, membrane regions with prolonged action potentials are a source of depolarizing current for the other, and repetitive activity may be initiated at transitional regions. After a single stimulus in either axon region, interactions between action potentials of different durations usually led to rebound, or a short burst, of action potentials. Complex interactions between two axon regions whose action potentials have different durations resembles electric activity recorded during some cardiac arrhythmias.

Action Potentials↗