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Biomedical subjects

J D Miller

Publications and source records attributed to J D Miller.

At least 361 records · Page 20Linked to original sources
PubMed1984

Naloxone antagonism of stress-induced augmentation of frontal cortex dopamine metabolism.

Foot shock stress selectively elevates dopamine metabolism in the medial frontal cortex but not nucleus accumbens or caudate nucleus. Pretreatment with a low dose of naloxone, an opiate antagonist, reversed the elevation in medial frontal cortex dopamine metabolism observed after foot shock. These data support the hypothesis that the stress-induced release of endogenous opioids cause an excitation of mesocortical dopamine neurons.

Animals↗
PubMed1984

Auditory processing of the acoustic patterns of speech.

The auditory processing of the acoustic patterns of speech relevant for the perception of phonetic units is discussed in terms of a three-stage generic model of phonetic perception. It is argued that the auditory system analyzes each brief segment of the acoustic waveform of speech for tonal components and the shape of the "spectral envelope." The presence and pattern of tonal components is used in the perception of voicing and pitch. The shapes of spectral envelopes and their dynamics induce the perception of phonetic units. The important attributes of the spectral-envelope patterns are identified.

Audiometry, Speech↗
PubMed1984

Dehydration and serum biochemical changes in marathon runners.

The effects of a competitive marathon race on serum biochemical and haematological parameters have been evaluated. Blood samples were obtained shortly before and immediately after the race; urine samples were also obtained before and after the race. Body weight was recorded pre- and post-race. During the race subjects consumed a total of 1.41 of either water or a dilute glucose-electrolyte solution. The average weight loss of the runners was 2.09 +/- 0.77 kg (mean +/- SD), corresponding to 2.9 +/- 0.8% of body weight. Small but significant increases in both haematocrit and haemoglobin concentration occurred; plasma volume was calculated to decrease by 4.7%. Serum potassium concentration showed no change, but the response was highly variable; serum sodium concentration increased in line with the decrease in plasma volume. In the group of subjects drinking water during the race, the pre-race plasma glucose concentration was 5.3 +/- 1.2 mmol . l-1, this was unchanged after the race (5.0 +/- 1.2 mmol . l-1). A significant increase (P less than 0.01) in the plasma glucose concentration, from 5.2 +/- 0.6 to 6.0 +/- 1.5 mmol . l-1 occurred in the group of subjects drinking the glucose-electrolyte solution. Apart from this, there were no significant differences between the two groups.

Adult↗
PubMed1984

Complications of tracheostomies in neurosurgical patients.

The records of the neurosurgical patients with tracheostomies who were treated at the University of Mississippi Medical Center during the past 5 years were reviewed. Of the 84 such patients, 45% had posttracheostomy complications, including pneumonitis, pneumothorax, pneumomediastinum, infected stoma, subcutaneous emphysema, tracheal stenosis, aspiration, swallowing dysfunction, and tracheoarterial fistula. Reported complications related to prolonged nasotracheal intubation, the alternative to tracheostomy, are reviewed. These complications appear to be less frequent and less serious than those of tracheostomy, in the authors' experience as well as in the reports of others. It is concluded that in neurosurgical patients, tracheostomy is not a benign procedure. Unless a specific indication for tracheostomy exists, consideration should be given to the use of prolonged nasotracheal intubation for airway maintenance.

Adolescent↗
PubMed1984

Social learning and teenage drug use: an analysis of family dyads.

This analysis of drug use in family dyads draws upon data from a series of nationwide studies in which interviews were conducted separately with teenagers and with older members of their families, i.e., their mothers, fathers, and older siblings. The interview schedule for these studies examines each individual's personal experience with a broad range of psychoactive substances. Thus, to the extent that behavioral similarities do occur in family dyads, "same drug links" can be compared to "cross drug links," providing a basis for differentiating evidence of direct imitation from less specific patterns of behavioral similarity. The theoretical implications of these findings are discussed.

Adolescent↗
PubMed1984

Calcium-loaded microsomes from uterine smooth muscle. A biological system to test for calcium ionophore action of prostaglandins.

Smooth muscle microsomal vesicles were loaded with calcium in the presence of oxalate and ATP. The intact vesicles that contained calcium oxalate crystals were separated by ultracentrifugation from empty vesicles. This results in a unique model system, composed of a biologically active membrane with virtually all of the calcium inside. Intravesicular calcium is differentiated from externally bound calcium using ionophore X537A and EGTA. EGTA released calcium slowly with a half time of 93 min. The ionophore X537A rapidly released calcium with a half time of 12 min. This model can be used to test for calcium ionophoretic action. Prostaglandin (PG) E2 and prostacyclin (PGI2) were tested in this system. We found that PGE2 and PGI2 did not change calcium permeability.

Calcium↗
PubMed1984

Possible dissociation between insulin binding and insulin action in isolated fetal rat hepatocytes.

To directly examine the relationship between insulin receptors and insulin action in fetal tissue, we compared insulin receptor characteristics and insulin-mediated 14C-glucose incorporation into glycogen, as well as glycogen synthase activity, in freshly isolated hepatocytes from 21-day fetal (F) and adult (A) rats. Viability of hepatocytes was documented by trypan blue exclusion (greater than 90%), time-dependent 14C-leucine incorporation into protein, and dose-related incorporation of glucose into glycogen. Percent specific binding of 125I-insulin per unit protein was significantly higher in F than A liver plasma membranes (32.2 +/- 0.3 versus 18 +/- 2.4; P less than 0.01) and Scatchard plots revealed twice the number of receptors in F. Similarly, receptor number per cell surface area was threefold higher in F than in A (150 versus 50 sites/micron2). At a fixed medium glucose concentration of 11.2 mM, insulin stimulated 14C-glucose incorporation into glycogen in a dose-related manner in A with an apparent Km of 1.0 ng/ml and Vmax at 5-10 ng/ml corresponding to 30-40% of total receptor occupancy; no effect was obtained in F with insulin up to 100 ng/ml. Net glucose incorporation into glycogen (nmol/10(6) cells/h) increased progressively with increasing medium glucose concentrations ranging from 1.4 to 27.8 mM; incorporation by F was significantly greater than by A at each glucose concentration. However, whereas insulin at 100 ng/ml significantly augmented net glucose incorporation at each glucose concentration in A, no effect of insulin was apparent in F.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1983

Activity of mesencephalic dopamine and non-dopamine neurons across stages of sleep and walking in the rat.

Single unit activity of dopamine and non-dopamine neurons in the substantia nigra and ventral tegmental area was recorded across stages of sleep and waking in the rat. These stages consisted of slow wave sleep (SWS), rapid eye movement (REM) sleep, awake-quiet (AQ) and awake-moving (AM). The dopamine neurons showed no change in mean firing rate across the stages of sleep or waking. During REM sleep, however, the dopamine cells fired with a more variable interspike interval than during SWS. In contrast, non-dopamine neurons in the substantia nigra and ventral tegmental area showed large increases in firing rate in REM compared to SWS, and in AM compared to AQ, without showing changes in interspike interval variability. In conclusion, whereas other monoaminergic neurons and various cortical and subcortical neurons exhibit marked changes in firing rate across the stages of sleep and waking, the dopamine neurons are unique in their lack of change in firing rate across stages.

Action Potentials↗
PubMed1983

DiGeorge's syndrome in monozygotic twins. Treatment with calcitriol.

Monozygotic male twins with DiGeorge's syndrome had facial dysmorphism, cardiovascular abnormalities, hypocalcemia, and immunodeficiency; however, they showed differences in several aspects of this developmental complex. An early gestational insult, rather than a mutation, may be one cause of this heterogenous disorder. One twin had clinically appreciable hypoparathyroidism and had received calcitriol since early infancy. Despite close monitoring of therapy, he experienced two episodes of unexpected and prolonged hypercalcemia. Following the first episode, he was eucalcemic for nine weeks without therapy, attesting to the prolonged biological effects of calcitriol when used in the treatment of hypoparathyroidism.

Calcitriol↗
PubMed1983

Dopamine metabolism and receptor sensitivity in rat brain after REM sleep deprivation.

Different dopaminergic mechanisms that could explain behavioral supersensitivity to amphetamine or apomorphine in REM-deprived rats were examined. Four days of REM sleep deprivation induced a highly significant elevation in striatal DOPAC relative to normal controls, but not to stress controls. DOPAC levels in frontal cortex were not affected in any of the groups. Post synaptic D2 receptor number (Bmax) and affinity (Kd) were unchanged in both terminal regions. Similarly, no changes in pre-synaptic receptor sensitivity (apomorphine-induced inhibition of tyrosine hydroxylase) occurred in striatum. A stress control group exhibited no changes in any of the biochemical measures in comparison with either the REM deprived group or unstressed controls. Thus, the enhanced response to dopamine agonists reported previously is not due to altered dopamine receptor sensitivity. Alternative hypotheses to explain enhanced responses to direct and indirect acting dopamine agonists are discussed.

Animals↗
PubMed1983

Computed tomography of the craniocervical junction in rheumatoid arthritis.

Thirty-three patients with rheumatoid arthritis had computed tomographic examination of the craniocervical junction. This demonstrated soft tissue features which have not previously been described in published reports. A low attenuation lesion between the odontoid and the transverse ligament shown in 11 patients was considered a premonitory sign of rupture of the transverse ligament or a manifestation of active disease. Computed tomography revealed spinal cord compression in 3 patients and ligamentous changes in the transverse ligament and the alar and spinal ligaments in 26 patients. Erosion of the odontoid was shown in 19 patients and subluxation in 20 patients. No relationship could be found between the clinical signs and symptoms and the radiological abnormalities except in the case of cord compression.

Adolescent↗