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Biomedical subjects

W H Bailey

Publications and source records attributed to W H Bailey.

At least 19 recordsLinked to original sources
PubMed1996

Human perception of electric fields and ion currents associated with high-voltage DC transmission lines.

The objective of this study was to assess the ability of humans to detect the presence of DC electric field and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods; one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines.

Adolescent↗
PubMed1990

Analysis of radionuclide arthrograms, radiographic arthrograms, and sequential plain radiographs in the assessment of painful hip arthroplasty.

An analysis of sequential plain radiographs (XR), radionuclide arthrography, (RNA), and radiographic arthrography (RGA) was performed to determine the efficacy and usefulness of each study in the diagnosis of loosening of prosthetic hip components. Over a 2-year-period, 65 hip prostheses were assessed before operation using each type of study; these results were compared to the intraoperative assessment of the status of the components. Of the three studies, sequential plain radiographs were overall the most accurate, sensitive, and specific. Radionuclide arthrography was of no use on the acetabular side but quite useful on the femoral side, especially in cases with only minimal femoral component loosening. Radiographic arthrography was overall the least accurate or sensitive of the three studies performed.

Aged↗
PubMed1987

Differential glucose utilization in the parafascicular region during slow-wave sleep, the still-alert state and locomotion.

Regional cerebral glucose utilization (CGU), detectable by the uptake of 2-deoxy-[14C]glucose [( 14C]2DG), was examined during 3 behavioral states--slow-wave sleep (SWS), the still-alert state (SAL) and locomotion (LOC). Examination of the autoradiograms, generated by exposing the [14C]2DG incorporated brain sections to Kodak Royal X Pan film revealed a high level of uptake bilaterally and discretely in the parafascicular (PF) region during these behaviors. This pattern of [14C]2DG uptake does not correspond to any of the anatomical structures previously identified by histo- and cytochemical methods, including the [14C]2DG method. Further, optical density measurements of this region indicated that the [14C]2DG uptake was significantly lower during SWS than during SAL or LOC. The present finding is compatible with the interpretations of previous physiological and behavioral studies that there is an inhibition by cells at the PF relay to the dentate gyrus that is lowered during the SWS compared to the SAL state, thus allowing preferential brain-stem activation of the dentate gyrus.

Animals↗
PubMed1987

Acute exposure of rats to air ions: effects on the regional concentration and utilization of serotonin in brain.

Exposure to electrically charged gas molecules (air ions) has been reported to influence physiological and behavioral functions in animals and humans although there is controversy as to whether these findings are valid. A popular hypothesis concerning the reported effects of air ions is that alterations in serotonin (5HT) metabolism, particularly in the brain, are involved. We measured the concentration and turnover of 5HT in rats exposed to 5.0 X 10(5) ions/cm3 for up to 66 hours. Contrary to previous reports of other investigators, we were unable to demonstrate any effect of exposure to air ions or associated DC electric fields on the concentration or turnover of 5HT in rats under carefully controlled and characterized exposure conditions.

Air Ionization↗
PubMed1986

Ion exposure chambers for small animals.

Ion exposure chambers that have been designed and tested for use in biological and behavioral research with small animals are described in this report. The chambers exhibit an acceptable degree of uniformity in ion concentration, current density, and electric field within the exposure area. Gaseous by-products of corona discharge (O3 and NO2) have been measured and found to be less than .01 ppm and less than .1 ppm, respectively. Filtered air is fed to the individual exposure chambers, and temperature and humidity are well controlled. Noise due to corona and the air delivery system has been measured.

Air Ionization↗
PubMed1986

Behavioral monitoring of rats during exposure to air ions and DC electric fields.

Air ions and direct current (DC) electric fields have been reported to exert subtle behavioral and biological effects on rodents and humans. These effects often appear inconsistent, yet there have been few attempts to resolve these inconsistencies by experimental replication. Rats exposed to negatively or positively charged air ions over a wide range of concentrations and exposure periods have been reported to show alterations in their level of locomotor activity. In this study, locomotor activity of Sprague-Dawley rats was quantified during exposure to either unipolar air ions and DC fields of the same polarity or DC fields alone. Both polarities were studied. Air ion concentrations were 5.0 X 10(3), DC fields were 3 kV/m, and exposures lasted 2, 18, or 66 h. In one experiment rats were exposed to DC fields of 12 kV/m. No exposure condition exerted any effect on locomotor activity or rearing behavior. In addition, no behavioral perturbations were observed after the onset of any of the exposure conditions, suggesting that the rats may have failed to detect the altered environment.

Air Ionization↗
PubMed1985

Regional turnover of norepinephrine and dopamine in rat brain following acute exposure to air ions.

Exposure to air ions has been reported to influence serotonin (5HT), although critical reviews of these studies and previous measurements in our laboratory of the concentration, release, and utilization of brain 5HT indicate that neither the data nor the interpretations of the data are particularly convincing. Measurements of other possibly relevant neurotransmitter systems--norepinephrine (NE) and dopamine (DA)--were made in brain regions selected because of their importance in the modulation of brain functions relating to motivation, arousal, endocrine function, and motor activity, all responses that have been reported to be influenced by air ion exposure. Results indicate that exposure of male Holtzman rats to high concentrations (5.0 X 10(5)/cm3) of positive or negative air ions or to DC electric fields (3.0 kV/m) for periods up to 66 h failed to affect the concentration of NE or DA significantly in any of the brain regions.

Air Ionization↗
PubMed1984

Release of histamine by sympathetic nerve stimulation in the guinea pig heart and modulation of adrenergic responses. A physiological role for cardiac histamine?

Histamine has been reported to attenuate adrenergic responses in cardiovascular tissues. In guinea pig atria preloaded with [3H]norepinephrine, histamine diminishes the field stimulation-induced efflux of radioactivity; this effect has been attributed to an inhibition of norepinephrine release from nerve endings. To assess the possible physiological relevance of these findings, we have reinvestigated the effects of histamine on cardiac sympathetic responses and on the release of endogenous norepinephrine in the guinea pig heart isolated with its intact sympathetic innervation. Heart rate, left ventricular contractile force, and perfusion pressure all increased with increasing frequencies of sympathetic nerve stimulation (2-8 Hz). Histamine (3 X 10(-8) to 3 X 10(-7) M) caused dose-dependent attenuation of the responses to sympathetic stimulation. The ability of histamine to modulate nerve stimulation-induced norepinephrine overflow into the coronary effluent was dependent on whether the heart had been preloaded with norepinephrine. Whereas histamine did not cause a significant reduction in nerve stimulation-induced norepinephrine overflow in hearts from untreated animals, histamine significantly reduced stimulation-induced norepinephrine overflow in hearts from guinea pigs that had been pretreated with norepinephrine before sacrifice. Histamine also attenuated the increases in left ventricular contractile force, perfusion pressure, and heart rate, which result from the intracardiac administration of norepinephrine (0.16-microgram bolus injection). In this respect, histamine was as effective as it was in inhibiting the responses elicited by nerve stimulation. Thus, in normal animals, the negative modulatory effect of histamine on adrenergic responses can be attributed largely, if not totally, to a postjunctional mechanism. In contrast, a prejunctional action of histamine may contribute significantly to the negative modulation observed in norepinephrine-preloaded hearts. Since we have observed a large increase in the amount of endogenous histamine present in the coronary effluent after sympathetic stimulation (930 pg during the 30 seconds poststimulation vs. 240 pg during 30 seconds prestimulation), as well as a prolongation of nerve stimulation-induced cardiac responses in the presence of the H2 receptor antagonist tiotidine, we postulate that histamine plays a physiological role as a modulator of sympathetic responses in the heart.

Animals↗
PubMed1981

Revision of total knee replacement.

In the London and Toronto areas between 1969 and 1978, 597 patients had 661 cemented knee replacements. Eighty-nine (13.5%) prostheses failed; 73 of them were revised. Nineteen (2.9%) failed primarily because of infection. The revised replacements were examined and rated using a modification of the British rating system. The overall results of revision were excellent or good in 30% and fair or poor in 52%. Fusion was attempted in two patients after revision. In 16 patients with failed replacements that were not revised, fusion was attempted in 9; 4 of the 16 patients had amputation. The results of failure in knee replacement surgery are similar to those of hip replacement, but are helped considerably by lower patient expectation.

Aged↗
PubMed1981

Unicompartmental knee replacement.

The results of unicompartmental knee replacement in a series of 83 knees were reviewed for the period of 1970 to 1978; 30.1 percent achieved good or excellent results; 48.2 percent fair or poor results; 21.7 percent were failures. The vast majority of failures and poor results were due to technical errors. Only 9.6 percent of the nonoperated contralateral compartments required further surgery.

Aged↗
PubMed1980

Stress-induced depression of motor activity correlates with regional changes in brain norepinephrine but not in dopamine.

This experiment examined how inescapable tail shock alters the level of dopamine and norepinephrine within various brain regions of the rat and the relationship of these changes to the depression of motor activity produced by the shock. Following exposure to tail shock that is known to interfere with acquisition of active behavioral tasks, animals were briefly tested for spontaneous motor activity and then sacrificed for neurochemical measures. Norepinephrine and dopamine levels in the frontal cortex, brain stem, striatum, olfactory tubercle, hypothalamus, hippocampus, septum, and amygdala were measured by a sensitive radioenzymatic technique. Exposure to 45 min of tail shock did not alter motor activity significantly, but shock sessions of 60 and 75 min duration produced a marked decrease in motor activity. Levels of dopamine were found to be very little changed in all brain regions studied except for the hypothalamus, in which a substantial rise in dopamine level was observed. Norepinephrine levels, in contrast, fell in many brain regions in response to shock. The fall in norepinephrine levels observed in two brain regions was significantly correlated with the decline in motor activity (brain stem r = +0.70, hypothalamus r = +0.60). These data suggest that deficits in active motor behavior produced by shock parameters similar to those used in this study may reflect concomitant disturbances of noradrenergic function in specific brain regions.

Animals↗
PubMed1979

The results of revision of total hip arthroplasty.

The results of 140 total hip revision procedures for "non-septic" loosening, dislocation, and fracture of the femoral stem or shaft have been personally reviewed and rated by the Harris method. The minimum follow-up period was six months: thirty-three (24 per cent) showed excellent or good results, seventy-two (51 per cent) showed fair or poor results. Subsequent excision arthroplasty was performed in thirty-one patients. The infection rate for these revision procedures was very high, suggesting that many were already infected at the time of revision, and that every "loose" hip must be assumed to be infected until proved otherwise. The mortality rate of 3 per cent was surprisingly low after more than one major surgical procedure in these elderly patients.

Aged↗
PubMed1978

Effect of ACTH 4-10 on passive avoidance of rats lacking vasopressin (Brattleboro strain).

The hypothesis that the effects of ACTH 4-10 on avoidance are mediated via the release of endogenous vasopressin was investigated. To test this hypothesis, we observed the effect of ACTH 4-10 on the passive avoidance of Brattleboro rats with diabetes insipidus resulting from a total genetic deficiency of vasopressin (DI) and Brattleboro rats without diabetes insipidus (HE). Normal Long-Evans rats (LE) were also included for comparison purposes. The results did not support the hypothesis. ACTH 4-10 did influence the passive avoidance of DI rats; this should not have occurred if the release of endogenous vasopressin is necessary for ACTH 4-10 to influence avoidance.

Adrenocorticotropic Hormone↗