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Biomedical subjects

A J Miller

Publications and source records attributed to A J Miller.

At least 163 records · Page 9Linked to original sources
PubMed1982

Electromyographic analysis of the functional components of the lateral pterygoid muscle in the rhesus monkey (Macaca mulatta).

Electromyographic recordings (EMG) obtained from intramuscular electrodes inserted in the lateral pterygoid muscle (lat. pt.) of 29 juvenile and adolescent monkeys were assessed in relation to the recorded activity of three jaw elevating muscles, temporalis, masseter and medial pterygoid, and a jaw muscle depressor, the geniohyoid. The lat. pt. was recruited in one of three patterns: (1) only during mandibular depression, (2) during both depression and elevation, or (3) only during elevation of the jaw. The discharge of fibres in the lat. pt. during closing movements occurred bilaterally in 9 of 21 recordings. Simultaneous recordings from the anterior temporalis, medial pterygoid and the ipsilateral lat. pt. indicated completely different discharge patterns of the three muscles. In 9 recording sessions, two pairs of electrodes were placed in the same lat. pt. The discharge patterns from the two pairs were different in 5 of the recordings. In one region, the fibres were active only during depression, whereas in the other region fibres discharged only during elevation of the mandible. The data support the concept of two groups of fibres with separate functions within the lat. pt. and suggest that adaptation to oral respiration utilizes the two groups in distinctive patterns.

Animals↗
PubMed1982

Deglutition.

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Animals↗
PubMed1981

The effect of photochemotherapy on the cardiovascular system.

Photochemotherapy, consisting of the oral administration of psoralens plus long-wave ultraviolet radiation (PUVA), involves standing in a warm light cabinet for a prolonged time. This study was done to evaluate the cardiovascular reactions in normal patients and in patients with cardiac disease receiving PUVA therapy. Of forty patients studied, six had cardiovascular disease and sixteen had essential hypertension. Holter monitoring during treatment revealed no significant arrhythmias. All patients had a modest increase in heart rate at the end of PUVA, with a mean increase of 22% of baseline. Blood pressure was not significantly changed, and 12-lead electrocardiograms done in twenty-two of the patients before and after PUVA showed no significant changes. Our patients, including those with cardiovascular disease and hypertension, tolerated the PUVA therapy without significant subjective reactions and without evidence of excessive cardiovascular stress.

Adult↗
PubMed1981

The efficacy of an aromatic retinoid, Tigason (etretinate), in the treatment of Darier's disease.

Eighteen patients with Darier's disease were treated for at least 3 months with the oral aromatic retinoid Tigason (etretinate, Ro 10-9359). Seventeen of the 18 patients improved but adverse effects were seen in all patients, and were particularly severe in 6. No haematological or biochemical abnormalities were detected during treatment. We conclude that Tigason is an important advance in the treatment of Darier's disease but adverse effects restrict its use in some patients.

Adolescent↗
PubMed1980

Postnatal development of presynaptic terminals in the gigantocellular tegmental field (FTG) of the rat.

Presynaptic boutons of the gigantocellular tegmental field (FTG) of the brain stem reticular formation were analyzed by sterological techniques for changes in numerical and volumetric density during early postnatal development. Electron microscopic analysis revealed that presynaptic boutons increased in numerical density and volumetric fraction during the first 15 postnatal days. By day 15, the presynaptic boutons had reached the numerical density and volumetric fraction seen in the adult tissue. Myelination was not evident ultil day 10 and by day 30 contributed over 45% to the total volume of the FTG tissue. Presynaptic boutons were differentiated into those with spherical vesicles and those with predominantly polymorphic (i.e. oblong) vesicles. Both types of presynaptic boutons were present at day 1, but over the next 30 days the percentage of boutons with polymorphic vesicles increased to over 40%. These results revealed that the FTG region of the rat demonstrates its synaptogenic period during the earliest postnatal days. The differentiation of the synapse into two types within the FTG region suggests a morphological basis for alterations in function during early maturation.

Aging↗
PubMed1978

Spectral analysis of the electromyogram of the temporal muscle in the rhesus monkey (Macaca mulatta).

Spontaneous EMG activity of one mandibular elevator and postural muscle, the anterior temporalis, was recorded from 20 unanesthetized rhesus monkeys subjected to 4 experimental protocols. The EMG activity was analyzed with a spectral analyzer to determine changes in particular frequency bandwidths after (1) administering a dissociative drug, (2) placing weights on the mandible, (3) detaching the muscle, and (4) adaptation of the muscle to oral respiration. The mean distribution of frequency components indicated that ketamine--HCl increased the power of all frequencies below 400 c/sec, particularly those at 20--40 c/sec. A period of hyperactivity and increased recruitment and discharge of motor units occurred within the first 30 min following administration of the drug. Passive and sustained lowering of the jaw with increased weights indicated that increasing the front incisor distance 2--4 cm significantly decreased the frequency components below 400 c/sec accompanying a decrease in active motor units. Comparison of frequency components of the temporalis EMG before and within 40 days after detachment suggested some subtle variations in the mean distributions predominantly around 200 c/sec but without significant changes. Comparison of the mean spectral distribution between 8 nasal-breathing and 8 oral-breathing monkeys indicated a significant loss of power in the normal dominant frequency range of 20--100 c/sec in the oral respiratory group except for enhancement of the 20 c/sec bandwidth. The results suggest that the anterior temporalis alters its EMG activity during both short (i.e., min, h) and long-term (i.e., months, year) adaptations of the muscle.

Animals↗
PubMed1977

Variations of the intraesophageal pressure with maturation in the postnatal piglet.

Variations in intraesophageal pressure (Pes) to 5-min exposures of 100% O2, 10% O2, and 6% CO2 were studied in successive days during the first 2 months of 8 piglets. Pressure measurements were integrated over time to obtain mean pressure changes for each minute. Initial exposure to 100% O2 decreased the mean pressure in all piglets followed by an increase over the next 4 test minutes. 5 of 8 piglets demonstrated maximum increases (25--55% above control) at 5 days and between 15 and 22 days; 3 piglets only at 5 days. Initial exposure to 10% O2 increased the pressure in all piglets followed by a decrease pressure (-10%) in the next 4 min when the piglets were less than 22 days, and an increase (15--70%) when above this age. Exposure to 6% CO2 increased the pressure throughout the 5-min test period with the maximum increase (140--160%) at the earliest ages tested of 5 days.

Age Factors↗
PubMed1977

The bilateral response of the temporal muscle in the rhesus monkey (Macaca mulatta) to short-term detachment of the muscle and increased loading of the mandible.

The electromyographic background activity of the temporal muscle was observed after short-term detachment of the muscle and with increased loads on the mandible. Detachment of the muscle increased its mean spike discharge within the first 24 days but without significant changes in the spectral components. Loading the mandible decreased both the spike discharge and spectral components.

Animals↗
PubMed1976

Characterization of the postnatal development of superior laryngeal nerve fibers in the postnatal kitten.

A combined electron microscopic and electrophysiological study of the superior laryngeal nerve (SLN) was undertaken in postnatal kittens ranging in age from 1-63 days. The superior laryngeal nerve is predominantly a sensory nerve innervating the upper respiratory tract, and could play a potential role in the modulation of respiration, particularly in the infant animal. Distribution of fibers in the developing SLN indicates that within the first postnatal month, 75% of the fibers are unmyelinated, and by 42 days, the myelinated fibers increase in number to approximately 50%. Of the myelinated fibers present in the one day old kitten, 3-4% of those exceeded 4 mum in total diameter, which is the minimum diameter for normal conduction velocity of action potentials. The distribution of the diameter sizes of the myelinated fibers is bell-shaped within the first 45 days after which the curve becomes skewed to the right (43-61 days; mean 2.6 mum, range 0.5-8.0 mum) to resemble the adult distribution of myelinated fibers (mean 4.2 mum, range 1.6-13.0 mum). Two variable plots of myelin width to axon diameter suggest a steeper slope for developing fibers as compared to that of the adult fibers. Electrical stimulation of the sectioned SLN indicates that evoked potentials could be recorded from the recurrent laryngeal nerve innervating the laryngeal intrinsic muscles and from the hypoglossal nerve to the tongue musculature in the youngest kittens tested (i.e., age 9 days). Stimulation at selected frequencies of 3 and 30/sec readily evoked apnea in the youngest kitten studied (i.e., age 5 days), while swallowing was more readily evoked at 28-30 days when using electrical stimulation.

Age Factors↗