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Biomedical subjects

J Miller

Publications and source records attributed to J Miller.

At least 1,369 records · Page 76Linked to original sources
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Differences in frequency dependence of quinidine effects on force, dV/dtmax and action potential duration.

In the left atria of the guinea-pig heart, quinidine produces a transient inotropic effect that is largest at low rates of stimulation; at high rates, the negative inotropic action of quinidine prevails. In contrast to the depression of the maximum rate of depolarization (dV/dtmax), the quinidine-induced prolongation in action potential duration was largest at low rates of stimulation. Recovery from block during rest was observed only for dV/dtmax; the prolongation in action potential duration, however, did not reverse but became most prominent after rest. The differences in frequency dependence of quinidine-induced decrease in dV/dtmax and prolongation of action potential duration can be explained if the drug interacts preferentially with the sodium channels while they are in an open or inactivated state, but with potassium channels while they are closed.

Action Potentials↗
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Leukoencephalopathy in normal and pathologic aging: 1. CT of brain lucencies.

Central white matter lucencies are commonly seen in CT scans of elderly patients. Reports in the literature have implicated demyelination due to subcortical vascular disease (Binswanger disease) as the cause of these lucencies. Binswanger disease, however, is thought to be rare. Because of this apparent discrepancy we decided to determine the incidence and to attempt to define the clinical significance of the CT white-matter changes in a study population at New York University Medical Center. The studies of 275 normal and demented subjects, ages 23 to 85 years, were reviewed. All subjects received neurologic, psychiatric, and medical evaluation, formal psychometric evaluation of their cognitive status, and a CT scan. CT scans were evaluated for the presence and severity of white-matter changes (leukoencephalopathy). The incidence and severity of white-matter changes increased significantly with age (p less than 0.01). Leukoencephalopathy was consistently more common in demented patients than in normal subjects, but the difference was not statistically significant, and the severity of the leukoencephalopathy was not related to the severity of dementia (p less than 0.05). Five patients (ages 74 to 95 years) with a clinical diagnosis of Alzheimer disease who had CT evidence of lucencies were examined at autopsy. Neuropathology demonstrated extensive changes of Alzheimer disease in one brain and mild-to-moderate changes in the other four brains; areas of white-matter rarefaction were present in all brains, with microscopic evidence of arteriolar hyalinization. This study demonstrates that leukoencephalopathy is strongly related to the aging process and is seen in both "normal" and cognitively impaired individuals who have no other evidence of vascular disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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Dental disease as an indication of nutritional problems.

This study was made of 293 Nigerian children (aged 2-6) to relate height and weight to dental disease. Nigerian children from large families were shorter, lighter, and had a poorer periodontal condition than children from smaller families.

Body Height↗
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Guidelines for making health education work.

The results of a number of studies which have indicated the limited effectiveness of health education efforts using the mass media are reviewed. The cause of these failures, according to the authors was the inability to apply a number of principles of effective design to the instructional materials used in the mass media. The basic slide show produced by the neighborhood health center for its own population may be more effective than a nationally televised spot announcement because locally prepared material can be sharply focused on the learner's characteristics and the specifically desired outcome behavior. The authors list 10 guidelines for the construction of effective instructional materials: define outcome measures, analyze relevant characteristics of the learner, gain and maintain the learner's attention, establish the learner's vulnerability, demonstrate the needs for action, establish the learner as an agent, establish the learner's effectiveness, provide for practice, repeat key facts, and generalize to similar situations. The principles of social reinforcement that must accompany health education instruction if behavior is to be modified are outlined. How environmental factors such as time, distance, expense, and the organization of health services hamper desired behavior outcomes is also discussed.

Audiovisual Aids↗
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Simulation of physical and biological aspects of GCR in ground-based experiments.

Many aspects of the interplanetary radiation environment can be simulated using high-energy charged-particle beams at ground based accelerator facilities. Some of the criteria and parameters used to define science requirements for such simulations are discussed. Some results from a ground-based radiation transport experiment are used to illustrate these considerations.

Acceleration↗
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Solving the problem.

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Clinical Competence↗
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Functional implications of postural disequilibrium due to lead exposure.

Measurement of postural equilibrium has been employed as an indirect indicator of functional status of the nervous systems of 109 children (mean age: 5.8 +/- 0.78 years) from the Cincinnati Lead Program Project. The geometric mean blood lead for the first five years of life (PbB05) was 11.9 +/- 1.5 micrograms/dL. Postural sway associated with upright balance was noninvasively quantitated with a microprocessor-based force platform and four tasks performed for 30 sec each by the subjects. A covariate-adjusted multiple regression analysis showed statistically significant associations between PbB05 and the postural sway for the task requiring primarily vestibular and/or proprioceptive systems input, implying potential functional impairment. These findings raised several new issues which are addressed here: (1) A dynamic task has been developed to further test the effect of perturbing those afferents' functional capabilities. (2) A method has been developed to quantitate the stability boundary of each subject to better characterize the limits of functionally-safe postural sway. (3) There is a need to perform the postural sway in a shorter duration than 30 sec so that children younger than five years of age can be tested for early identification of Pb-induced functional impairment of postural equilibrium.

Child↗