PubMed Health⌕ Search

Biomedical subjects

R T Jackson

Publications and source records attributed to R T Jackson.

At least 55 records · Page 3Linked to original sources
PubMed1991

Binding of [3H]-dopamine to human lymphocytes: possible relationship to neurotransmitter uptake sites.

Freshly isolated human lymphocytes from 11 healthy subjects had specific binding sites for dopamine which were dependent on time, temperature and sodium, and appeared to follow Michaelis-Menten kinetics. The apparent affinity constant (KD) of human lymphocytes for dopamine and the maximal number of binding sites (Bmax) were 109 +/- 21 nM and 2.66 +/- 1.75 pmol/10(7) cells, respectively. Dopamine binding was markedly affected by cocaine (IC50 = 150 nM) and other inhibitors of biogenic amine uptake. The relatively high potency of cocaine in competing for dopamine binding suggested that human lymphocytes may serve as a readily accessible model to detect changes in the neuronal uptake of dopamine and perhaps other monoamine neurotransmitters.

Adult↗
PubMed1991

Effect of head extension on equilibrium in normal subjects.

A dynamic posturography system was used to test the effect of 55 degrees head extension on postural sway in 20 normal subjects. There was a highly significant increase in sway with head extension under two conditions; in both, the support surface moves proportionally to body sway angle (sway-referenced feedback). The largest increase in sway occurred when the eyes were closed and the support surface was sway-referenced. This latter condition removes vision, reduces the effectiveness of ankle proprioception, and forces the subject to depend mostly on vestibular information for equilibrium. We suggest that head extension increases sway because the utricular otoliths are put into a disadvantageous position. This may be another example of the role of utricular input in the control of balance.

Adult↗
PubMed1991

Mechanism of action of some commonly used nasal drugs.

This article provides a brief description of the mechanism of action of drugs commonly used in the treatment of nasal disorders. These include oral and topical vasoconstrictors, antihistamines, atropine-like drugs, cocaine, topical corticosteroids, and mast-cell stabilizers.

Humans↗
PubMed1991

Enhancement of posturography testing with head tilt and energy measurements.

We have attempted to increase the sensitivity of dynamic posturography testing by adding head extension and sway energy measurement to the standard Equitest protocol. Both procedures were applied to 121 patients and to 89 normal subjects. A portion of the standard protocol was repeated with the patient's head extended 55 degrees. Head extension significantly increases the number of "falls" or losses of balance experienced by normal subjects 50 years or older. Using the formula, Energy = Force x Distance, and appropriate corrections for platform tilt and body weight, any previously recorded test can be analyzed with computer programming to give energy values in joules per kilogram. Adding the two criteria of head extension and sway energy to the standard protocol increased the percentage of patients classified as abnormal from 48 to 68 percent. The two added criteria are useful in separating symptomatic from asymptomatic subjects and patients.

Adult↗
PubMed1991

Reassessing 'hereditary' interethnic differences in anemia status.

The widely accepted hypothesis that significant differences in hemoglobin levels exist between African Americans and European Americans is critically evaluated. Most studies implying hereditary interethnic differences are derived from analyses of national cross-sectional surveys or smaller nonprobability samples. Yet those studies give inadequate consideration to the important nutritional and genetic variables that must be controlled for in acceptable comparative assessments of the heritable component of anemia. Missing but vital nutritional variables include reliable parameters of intake, absorption, and utilization of nutrients, and preexisting nutrient stores. Actual measures of confounding genetic conditions such as alpha-thalassemia and hemoglobin variants are also absent, although pronounced within-group diversity has been observed in both macroethnic groups. The likelihood that significant interethnic differences exist in the structural genes coding for hemoglobin level is nil given our species' molecular genetics and evolutionary history. Common recent African origins for all modern humans, as suggested by the fossil and molecular data, as well as our close biochemical affinities with chimpanzees and gorillas, suggest that biologically significant differences among populations of contemporary humans are unlikely. When the proper control of relevant epigenetic and genetic variables is maintained, the reported discrepancies tend to disappear.

Africa↗
PubMed1990

Separate hemoglobin standards for blacks and whites: a critical review of the case for separate and unequal hemoglobin standards.

There have been a number of reports that suggest mean differences between the hemoglobin (Hgb) levels of black and white Americans. Many of those reports have had as their basis various national US nutrition surveys. Early reports indicated that blacks had a 1.0 g/dl lower mean Hgb than whites. Later reports put the mean Hgb difference between 0.5 and 0.73 g/dl. Recent reports, in which either iron intake or iron status have been measured and controlled, indicate a mean Hgb difference of between 0.2 and 0.3 g/dl. Despite the variability in these mean Hgb differences, some reports call for the establishment of separate Hgb standards for black Americans. The need for separate Hgb standards is critically reviewed in light of alternative interpretations of early data and newer knowledge about the development, detection, and significance of iron deficiency. The suitability of national cross-sectional survey data to answer questions about Hgb standards without adequate experimental studies in questioned, especially since no genetic studies have been performed to indicate genetic differences in Hgb levels. Policy implications of a change from current standards are also discussed.

Adolescent↗
PubMed1989

Deaths from lung cancer and ischaemic heart disease due to passive smoking in New Zealand.

Passive smoking is increasingly recognised as a public health hazard. Among New Zealanders who have never smoked, the prevalence of exposure to spousal smoking has been estimated to be 12.7% for men and 16.1% for women. The prevalence of exposure to passive smoking in the workplace has been estimated to be 33.6% and 23.4% for never smoking men and women respectively. The pooled risk estimates from epidemiological studies of the health effects of passive smoking were used to estimate the numbers of deaths from lung cancer and ischaemic heart disease attributable to passive smoking in New Zealand in 1985. The pooled relative risk estimates for lung cancer mortality were 1.3 (95% confidence interval (CI): 1.1-1.5) in both men and women exposed to passive smoking at home, and 2.2 (CI 1.4-3.0) in both men and women exposed to passive smoking at work. Using these relative risk estimates, it was calculated that 30 lung cancer deaths (range: 11-41) were attributable to involuntary smoking in New Zealand in 1985. From pooled relative risk estimates of ischaemic heart disease death of 1.3 (CI 1.1-1.6) and 1.2 (CI 1.1-1.4) for exposure to spousal smoking in men and women respectively, it was estimated that a further 91 ischaemic heart disease deaths (range: 39-177) were due to passive smoking at home. The number of ischaemic heart disease deaths due to passive smoking in the workplace was even higher, at 152 (range: 62-224), assuming relative risks of 2.3 (CI 1.4-3.4) and 1.9 (CI 1.4-2.5) for men and women respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Quantitative assessment of pharyngeal bolus driving forces.

This study analyzes the differences between wet and dry swallows; a manofluorogram is used to determine forces that affect pharyngeal bolus flow. By defining bolus pressures, many of the limitations of pharyngeal manometry are surmounted. This makes manometry a more useful clinical tool. The study results indicate that only a small portion of pharyngeal-generated pressure is directly applied to the bolus. The manofluorogram demonstrates that bolus transit relies on the synergistic action of two pumps--the oropharyngeal propulsion pump and the hypopharyngeal suction pump. A technique is illustrated for quantifying the forces that affect bolus flow. Quantification of force can differentiate abnormal forces responsible for lingual, pharyngeal, and hypopharyngeal pathology in dysphagic patients. The degrees of impairment can be measured.

Adult↗
PubMed1989

Recent trends in asthma mortality, morbidity, and management in New Zealand.

Trends in mortality and hospital admission rates, prevalence, and drug sales, relating to asthma in New Zealand since 1960 were examined. Two epidemics of asthma death among people in the age range of 15-64 years occurred during this period with peak mortality rates more than four times pre-epidemic rates. Death from asthma was nevertheless rare compared with hospital admissions which have increased 20-fold in children and three- to fivefold in adults between 1960 and 1985. Asthma drug sales have also risen dramatically, particularly in the late 1970s when it is likely that a major change in the drug management of asthma occurred. Changes in asthma prevalence and severity may account in part for the increasing hospital admissions rates. However, the lack of any clear relationship between hospital admissions and death rates and the abrupt time course of the mortality epidemics suggest that changes in the management rather than in the disease itself may be responsible for the increased number of asthma deaths.

Adolescent↗
PubMed1988

Factors associated with active, refractory epistaxis.

This study addresses the underlying causes responsible for the severity and persistence of active, refractory epistaxis. Seventy-five patients referred because of treatment failure by primary care physicians showed hypertension and aspirin and alcohol abuse to be major factors in the refractory nature of their epistaxis. The majority of bleeding was located near the posterior floor of the nasal cavity and just posterior to Kiesselbach's plexus and was only associated with septal deviation, spurring, or mucosal abnormalities in 16 of the 75 patients. Seventeen of 67 outpatients required hospitalization. Standard laboratory tests were often inadequate determinants of etiology. Intractable epistaxis should be a signal for a thorough investigation of factors that influence clotting.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Timing of major events of pharyngeal swallowing.

Normal swallowing depends on the synergistic motion of the tongue, larynx, and pharyngeal wall to develop a bolus pressure gradient for bolus transit. However, few studies have provided timing relationships for clinical evaluations. To examine the timing relationships of pharyngeal anatomic motion, pressure generation, and bolus transit in the normal swallow, this study uses a new method, manofluorography, to correlate these swallowing aspects. Thirty-one events were timed by analyzing five swallows each in 14 normal subjects. A different perspective of pharyngeal physiology is presented.

Deglutition↗
PubMed1988

Bacteroides fragilis endocarditis.

We recently diagnosed and treated an unusual case of primary endocarditis due to Bacteroides fragilis, for which no underlying etiology was found. Antibiotic treatment involved multiple parenteral and oral antibiotics, and sensitivity studies allowed choice of antibiotics. Despite complications, the patient was cured. Few cases of Bacteroides fragilis endocarditis have been reported, and therapy has changed with newer antibiotics.

Aged↗
PubMed1988

Clinical application of the manofluorogram.

The purpose of this paper is to illustrate the clinical usefulness of simultaneous fluoroscopy and manometry, as analyzed by the manofluorogram, in the evaluation of dysphagia. Four quantitative parameters calculated from the manofluorogram are analyzed and compared in six representative cases of dysphagia. The manofluorogram adds diagnostic information which cannot be obtained by barium swallow or standard manometry.

Adult↗
PubMed1988

Do cholinergic neurons directly innervate nasal blood vessels?

The main aim of this work was to provide additional evidence that cholinergic neurons can induce nasal vasodilation by inhibiting norepinephrine release, not by a direct action on nasal blood vessels. We induced a degeneration of the nasal sympathetic neurons in order to observe the effects of electrical stimulation of the cholinergic neurons on nasal blood vessels. Electrical stimulation had no measurable effect. One interpretation of this result is that cholinergic fibers control vasomotor tone by inhibiting the output of the sympathetic neurons, i.e., they have a presynaptic influence. However, it should be stressed that the data were obtained from in vitro experiments, which may not reflect the true in vivo processes. Additional evidence was obtained to demonstrate that electrical stimulation of the in vitro nasal tissue causes contraction by the release of norepinephrine from remnants of sympathetic nerve fibers remaining in the tissue. Also, there is no evidence of transganglionic degeneration in the cervical sympathetic nerve.

Animals↗
PubMed1987

Lessons from the national asthma mortality study: circumstances surrounding death.

The circumstances surrounding all deaths from asthma in New Zealanders under 70 years of age between August 1981 and July 1983 have been analysed from information recorded or recalled by doctors or relatives of the deceased. Factors which may have reduced the time available for effective treatment of these severe attacks are described to draw attention to ways in which mortality might be reduced. For almost half of the 271 deaths medical help had not been called before the patient was in extremis. When medical help was summoned in sufficient time doctors commonly did not give corticosteroids or used them inadequately. Difficulties in using medical care and noncompliance with asthma management were common particularly in Polynesian patients. In 38% of patients some medical inadequacy appeared to contribute to poor long-term care and education. Failure of patients to attend for ongoing medical care, education and preventative treatment, or a medical failure to deliver these may have led to chronically reduced lung function. Any further deterioration may then have more rapidly led to a fatal outcome. Lack of patient or family awareness about how to detect and cope with an unusually severe attack was found and contributed to avoidable fatalities.

Asthma↗
PubMed1987

Astemizole. Its use in the treatment of patients with chronic vertigo.

Thirty-eight patients with chronic vertigo and positional and/or spontaneous nystagmus finished a double-blind study to determine the efficacy of astemizole on nystagmus and its symptoms. Patients with Meniere's disease were excluded. The study took 13 weeks with a follow-up examination. Six to eight noncaloric electronystagmograms were recorded at determined intervals. Three doses of the drug, 5, 10, and 20 mg/d, and placebo were tested. A patient was considered a responder if the number of nystagmic beats occurring in eight head and body positions was reduced by 50% or more and the symptoms of vertigo were greatly reduced. Twenty-eight of the 38 patients were responders. Blood levels of astemizole were related to effectiveness. Patients did not respond to placebo. The onset of drug effect was slow. Astemizole appears to be useful and safe to try on the patient with chronic dizziness.

Adult↗