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Biomedical subjects

A J Miller

Publications and source records attributed to A J Miller.

At least 145 records · Page 8Linked to original sources
PubMed1984

Experimentally induced neuromuscular changes during and after nasal airway obstruction.

Neuromuscular changes were studied by electromyography in rhesus monkeys which adapted to nasal obstruction for 2 years and then in the succeeding year recovered to nasal respiration. Obstructing the nasal passage with silicone plugs induced specific behavioral responses which remained for the duration of nasal obstruction and were lost within 8 days after removal of the plugs. Animals demonstrated individual variations, but more than 80% consistently maintained a lower mandibular posture for the entire 2-year period. Rhythmic mandibular, tongue, and upper lip movements were evident in fewer than 60% of the animals. Certain craniofacial and tongue muscles (the genioglossus, dorsal tongue fibers, digastric, geniohyoid, dilator naris, and vertically oriented fibers of the superior orbicularis oris, that is, lip-elevator fibers) were recruited rhythmically and remained rhythmically active throughout the entire 2-year period of nasal obstruction. This rhythmic activity ceased within 1 week after removal of the nose plugs. A tonic or consistent discharge was also induced in the genioglossus, dorsal tongue fibers, the geniohyoid, superior orbicularis oris, and lip-elevator fibers over the entire 2 years of nasal obstruction. Not all muscles lost their tonic discharge after removal of the nasal plugs. The genioglossus, geniohyoid, inferior orbicularis oris, and lip-elevator fibers discharged tonically during the recovery period. These data suggest that nasal obstruction can induce neuromuscular changes which extend beyond the period of obstruction and remain after the original stimulus for neuromuscular change has been removed.

Airway Obstruction↗
PubMed1984

Neuromuscular patterns in hemifacial microsomia.

This study was designed to establish the extent of neuromuscular abnormalities in different types of hemifacial microsomia and to relate these findings to the existing skeletal malformations. Neuromuscular recruitment patterns were established in twenty-three normal subjects. These patterns served as baselines for comparison with recruitment patterns obtained from forty-eight subjects with hemifacial microsomia. The anterior and posterior temporalis, masseter, suprahyoid, buccinator, platysma, mentalis, and upper and lower lips were studied electromyographically. Consistent presence or absence of recruitment for a given task was considered a significant finding with which the hemifacial microsomia data were compared. The subjects with hemifacial microsomia were divided into five groups according to type of mandibular malformation. Abnormal recruitment was found in all recorded muscles except the lips, mentalis, and buccinator muscles. There were variations in recruitment patterns within each group as well as among the groups. A relationship was found between the development of the gonial angle area and the recorded masseter activity. Muscle activity was recorded in the area of the temporal muscle, even in the absence of a coronoid process. It was found that after insertion into a new coronoid process the temporal muscle developed mass and palpable contraction. This study shows that in persons with hemifacial microsomia certain neuromuscular patterns may differ from the norm because of missing or underdeveloped muscles and because of the different relationship between the mandible, its attached muscles, and other structures.

Adolescent↗
PubMed1984

Cortisol and catecholamines changes as functions of time-of-day and self-reported mood.

Six male graduate students, unrestricted in their lifestyle, collected their own urine over a seven-day period: it was analysed for cortisol, noradrenaline, adrenaline and dopamine. At each urination subjects self-assessed their mood. On two separate days, blood samples were collected at 4-hourly intervals for plasma cortisol assay. Mean plasma cortisol levels showed the expected circadian variation, but two subjects had divergent patterns. Mean urine cortisol accumulation also showed circadian variation with a 2-4 hour lag behind plasma values. Mean urine catecholamine levels showed both time of day and considerable individual variation. A statistical procedure, involving comparison of two models, was developed to determine differences between subjects' excretion patterns. An underlying common pattern of cortisol and catecholamines excretion was found. Regression of hormone levels against self-assessed mood changes revealed correlations of (1) adrenaline accumulation with physical fatigue, (2) cortisol with alertness and (3) ratios of adrenaline, noradrenaline and dopamine with tenseness and irritability.

Adult↗
PubMed1984

Relationships between catecholamines in urine and physical and mental effort.

Excretion of noradrenaline and adrenaline was investigated in two experiments which included 3 physical test sessions and 3 mental test sessions (Experiment X) and a week of real-life situations (Experiment Y). An increased excretion of both catecholamines was found during each test in Experiment X. The noradrenaline excretion discriminated well between physical and mental tests, but one i.e. 35% VO2max. Adrenaline excretion discriminated the arithmetic test (AT) from the other mental tests. The noradrenaline/adrenaline ratio (NA/A) separated the AT from all other tests. The different adrenergic response patterns to physical and mental effort were confirmed in the real-life situations. The NA/A ratio reflected these differences. It was over 5 for physical activities and between 2 and 3 for mental activities. The different response patterns allow one to differentiate between physical and mental effort.

Adult↗
PubMed1984

Experimental study of muscle reattachment following surgical detachment.

The process of muscle reattachment was studied in rhesus monkeys using electromyographic and histologic techniques. The attachments of the temporal muscle were exposed on both sides and the muscle was detached from its origin on the right side in ten rhesus monkeys. EMG activity was recorded by fine wires placed intramuscularly within the anterior, middle, and posterior parts of the muscles before and after detachment. The control EMG activity recorded in the attached muscle showed a wide range of values, and there were no clear trends. Following detachment the range of values was also wide, and the differences in activity between the detached muscle and the contralateral attached muscle were not outside the range of difference normally observed between right and left sides. EMG activity was greater before detachment in 31.2% of the recordings and was greater after detachment in 29.4% of the recordings. Biopsies of bone and muscle were taken from normal attachment sites on the left sides and also from the right sides following detachment at one, two, three, four, six, and eight weeks and examined by light microscopy. New bone spicules were seen developing from the surface of the bone after two weeks that were oriented in the direction of the muscle fibers. The reattachment process is one in which new bone is formed on the surface of the bone and develops toward the end of the muscle to envelop the reorganizing tendon. Bone formation occurring on the surface of bones at the ends of muscles is not dependent on tension or viscoelastic properties of the muscle.

Animals↗
PubMed1984

Costs of school-based mouthrinsing in 14 demonstration programs in USA.

The purpose of this study was to determine the economic costs of school-based mouthrinsing in the demonstration programs. Costs for two complete years were expressed in 1978 dollars, and divided into explicit and implicit categories. Costs per participant were found to vary among programs (ranges of average total costs - period I: $2.35-$8.05, period II: $1.46-$7.94), and a tendency for some average costs to increase with size was identified. That costs were higher than the conventionally reported $0.50-$1.00 reflects 1) the organization of these federally funded programs and, 2) the use of an accounting method which describes the real economic costs of public programs.

Child↗
PubMed1984

Adaptation in the function of pharyngeal constrictor muscles.

The palatopharyngeus and pharyngeal constrictor muscles were studied by electromyography (EMG) and by direct observation with a flexible fiberoptic scope in the anesthetized as well as in the alert rhesus monkey. The muscles were monitored to determine the change in their discharge with nasal obstruction, head posture, head extension, and swallowing. The results indicated that certain regions of the middle and inferior pharyngeal constrictors never discharged during deglutition. Extending the head could induce a tonic discharge in fibers of the middle pharyngeal constrictor for the duration of head extension. Placement of water in the hypopharynx not only induced a sustained laryngospasm but also a tonic discharge in the select fibers of the superior and middle pharyngeal constrictors. Changing from a supine to an upright posture, or obstructing the nasal cavity, could induce a rhythmic discharge. These studies indicate that there are functional components of fibers within each of the anatomically recognized pharyngeal constrictors.

Airway Obstruction↗
PubMed1984

The development of an unconstrained elbow arthroplasty. A clinical review.

This paper describes the development, operative technique and results of an unconstrained total elbow arthroplasty. Forty-seven elbow replacements were carried out in 44 patients between 1974 and 1982. There was a high rate of loosening in the early condylar replacements. The results in patients with post-traumatic arthritis were poor. The later design employs an ulnar stem, with a humeral stem if the distal humeral bone stock is poor. When used in carefully selected patients with rheumatoid arthritis, pain is reduced significantly, stability and movement are preserved and function is improved.

Adult↗
PubMed1983

Treadmill exercise testing in hypertensive patients treated with hydrochlorothiazide and beta-blocking drugs.

Twelve patients with hypertension who did not become normotensive after treatment with hydrochlorothiazide alone were studied. Treadmill exercise testing was done before and after additional treatment to standing resting normotension with beta-blocker drugs. The double product (peak mean BP times peak heart rate) at peak performance fell significantly because of decreases in systolic arterial BP and heart rate, but diastolic pressures still rose with exercise in ten of the 12 patients, in seven of them to 100 mm Hg or higher. Thus, the data show that patients with hypertension treated to resting normotension with hydrochlorothiazide and a beta-blocker still often demonstrate a significant diastolic BP rise with exercise. In such patients, a rise in diastolic BP with exercise cannot be used as evidence of coronary atherosclerosis. The measurement of the arterial BP response to exercise is probably important in the assessment of the effectiveness of individual antihypertensive regimens.

Adrenergic beta-Antagonists↗
PubMed1983

Postnatal synaptic development of the rat.

Presynaptic boutons of the dorsomedial region of the nucleus tractus solitarius (NTS) were studied during the first 30 days of postnatal development of the rat. Electron micrographs were analyzed by conventional and stereological techniques to determine the area and volumetric density and fraction, and the number per linear length on both the dendrites and cell bodies. The numerical density and volumetric fraction of boutons in the NTS increased rapidly within the first 10 postnatal days. The number of boutons per area and volume remained stable between 10 and 30 days. Twice as many boutons synapsed on the larger dendrites than the cell bodies during the first 10 days, and then increased to 4 times the number of synapses per linear length on the cell body after the tenth postnatal day. The rapid synaptic development and shift in shift in sites of synaptic contact on neurons of the NTS suggest synaptic contacts rapidly change during early postnatal development.

Animals↗
PubMed1983

Detection of genotoxicity in fried bacon by the Salmonella/mammalian microsome mutagenicity assay.

The potential for mutagen formation in fried bacon and the possible reduction or elimination of this hazard was examined in the Salmonella/mammalian microsome mutagenicity assay using Salmonella typhimurium strain TA98. Alkaline dichloromethane extracts were prepared from green pork bellies, commercial bacon (nitrite-treated and nitrite-free), and pilot-plant bacon (nitrite-free). When fried, all forms of bacon and the green belly samples gave positive mutagenic responses with the plate-incorporation technique. Unfried samples were not mutagenic. Aroclor-activated rat-liver S-9 fractions plus NADPH were essential to demonstrate a mutagenic response. When the frying temperature was held constant (171 degrees C) maximum mutagen formation was observed in samples fried for 6 min; when samples were fried for 6 min a mutagenic response which increased with temperature, in a linear manner, was observed at temperatures above 125 degrees C. Volatile nitrosamines were not detected in the bacon samples. The data indicate the generation of one or more mutagens in fried bacon and green pork belly, the levels of which can be reduced by decreasing heating temperature and/or time.

Animals↗
PubMed1983

Nasal airway function as it relates to the timing of mid and lower facial osteotomies.

It has been established in primate studies that mouth-breathing can affect lower facial development. We submit that mouth-breathing has a similar effect on human development--specifically, that chronic mouth-breathing during growth contributes to long-face syndrome. When reconstructive surgery is contemplated for this deformity, we believe that the sequence of surgical steps is important and that particular attention should be given to enhancing nasal respiration. The possibility that mouth-breathing is a factor in relapse following mandibular surgery is discussed.

Adolescent↗
PubMed1983

A dose-response study of I3-cis-retinoic acid in acne vulgaris.

13-cis-retinoic acid has been used as a single agent in the treatment of seventy-six patients with previously unresponsive cystonodular acne. The study was carried out in a double-blind fashion using three doses of the drug. Ninety per cent of the patients responded with a 70% improvement in the acne severity. Sixty-six per cent of the patients experienced no further problems with their acne during follow-up. Side-effects were frequent. The 0.5 mg/kg b.w. dose is recommended for the initial course of treatment.

Acne Vulgaris↗
PubMed1982

Sequential neuromuscular changes in rhesus monkeys during the initial adaptation to oral respiration.

Experimental induction of oral respiration in primates altered the neuromuscular use of specific craniofacial muscles. Obstruction of the nasal passage in the rhesus monkey induced changes in the electromyographic discharge (EMG) of both mandibular and facial muscles during the first 6 months of adaptation. Eighteen craniofacial muscles were studied with regard to their type of neuromuscular pattern. The EMG discharge was analyzed in terms of whether it had a rhythmic discharge or a continuous recruitment of motor units. The results of the investigation revealed that certain muscles in the control monkey using nasal respiration could be rhythmically or continuously active, but no significant trend was apparent with either pattern over time. In contrast, a significant number of muscles became rhythmically active within the first month of adaptation to oral respiration in the experimental animals. The rhythmic pattern was evident in key muscles that actively depressed the mandible, protruded the tongue, altered the shape of the tongue, and raised the upper lip. Continuous activity was induced in the first month within the suprahyoid region and tongue but later, by the fifth month, in specific lip and elevator muscles. These results suggested that the neuromuscular system adapted immediately to nasal obstruction but would vary as to (1) which muscles would be important in the initial adaptation, (2) the mode of adaptation, and (3) the time when a particular pattern first began to be used.

Adaptation, Physiological↗