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Biomedical subjects

A Miller

Publications and source records attributed to A Miller.

At least 847 records · Page 47Linked to original sources
PubMedDate not supplied

Respiratory drive and pattern during inertially-loaded CO2 rebreathing: implications for models of respiratory mechanics in obesity.

Chest wall inertance (Iw) constitutes a mechanical load which is small in normal individuals, but increases in the morbidly obese. The effect of increased Iw on respiratory drive and pattern has not previously been investigated. We studied this effect by measuring rebreathing CO2 response in 10 normal subjects with and without a 45.5 kg inertial load. Changes in inspiratory occlusion pressure (P0.1), ventilation, respiratory rate, mean inspiratory flow (VT/TI) duty cycle (TI/TT), inspiratory and expiratory times, and [P0.1/(VT/TI)] were assessed. The P0.1 vs. PETCO2 response shifted to the left during inertial loading, while the slope remained unchanged (x-intercept = 36.7 +/- 4.9 mm Hg unloaded vs. 32.7 +/- 7.5 mm Hg loaded, P less than 0.05), increasing P0.1 from 18.5 +/- 8.0 to 21.0 +/- 7.6 cm H2O at PETCO2 = 6.5 mm Hg (P less than 0.005). Respiratory pattern was unchanged with the inertial load except for a slight decrease in tidal volume. The inspiratory transfer characteristic [P0.1/(VT/TI)] at PETCO2 = 65 mm Hg increased significantly (8.3 +/- 2.0 to 10.5 +/- 2.9 cm H2O.(L.sec-1)-1, P less than 0.025) illustrating the strategy of maintaining similar ventilation by increasing inspiratory force against the load.

Adult↗
PubMedDate not supplied

Beta-adrenergic receptor changes in learned helplessness may depend on stress and test parameters.

Behavioral deficits following inescapable stress (learned helplessness) may serve as an animal model of depression. Previous studies using foot-shock stress to induce learned helplessness and a bar-press test for the stress-induced behavioral deficit have found increased beta-adrenergic receptor density in the hippocampus of learned helpless rats. We replicated these experiments using a tail-shock stress and the shuttle-box test. In our experiments, rats that developed learned helplessness after inescapable stress did not demonstrate any significant differences in beta-adrenergic receptor density or affinity in the frontal cortex, cerebellum, or hippocampus compared to the nonhelpless rats, nor to the tested control rats. These results suggest that beta-adrenergic receptor changes in learned helplessness may depend on the specific stress and test procedures used.

Animals↗
PubMedDate not supplied

A new method for estimating T2 distributions from NMR measurements.

A semi-continuous relaxation model is constructed using sums of gamma functions and non-negative least squares for the inversion of Carr-Purcell-Meiboom-Gill (CPMG) echo data. No regularization is necessary for this approach, and yet the solution is stable even with noisy data. Test results derived from 60 echo trains are presented. Computational advantages of the method are presented.

Computer Graphics↗
PubMedDate not supplied

Quasi-hexagonal molecular packing in collagen fibrils.

Collagen molecules in native 66.8 nm (D) periodic fibrils are widely believed to be assembled into discrete, rope-like substructures, or microfibrils. Several types of microfibril have been proposed (2, 4, 5, 7- and 8-stranded) mainly on the basis of information contained in the medium angle X-ray diffraction patterns of native tendon fibres. These patterns show a series of equatorial and near-equatorial Bragg reflections which indicate that the collagen molecules are arranged on a three-dimensional crystalline lattice. The 4-stranded, 5-stranded and 8-stranded microfibrils are D-periodic with approximate diameter 3.8 nm, and these and the 2-stranded model are supposed to be packed on a three-dimensional lattice whose basal unit cell, (approximately) perpendicular to the fibril axis, is tetragonal (or quasi-tetragonal)with side a, a square root 2 or 2a, where a is approximately 3.8 nm. In this paper we describe a re-interpretation of the X-ray data which leads to a new model for the crystalline regions of the fibril, based on quasi-hexagonal molecular packing without microfibrillar sub-structures, and hence having the character of a molecular crystal.

Animals↗
PubMedDate not supplied

Tuberculosis and sudden death: a case report and review.

Although deaths from tuberculosis (TB) are increasing, TB-related sudden death (TBRSD) is rarely reported in the literature. We present a case report of fatal pulmonary TB with extrapulmonary extension in a patient infected with the human immunodeficiency virus (HIV) and a review of published reports of TBRSD in MEDLINE (1966 to October 2000). Forty-six cases of TBRSD were reported. The most common cause of TBRSD was tuberculous bronchopneumonia in 30 (64%) patients, followed by hemoptysis in 14 (30%) patients. Tuberculous myocarditis and isolated TB of the adrenal glands are seldom causes of TBRSD. The early detection of TB, use of directly observed therapy, and individualization of treatment can be helpful in decreasing the incidence of TBRSD.

Adult↗
PubMedDate not supplied

Clinical validation of automated spirometry used in surveys of large occupational groups: comparison with conventional water spirometry.

An accurate, rugged automated spirometer which provides immediate data is useful both clinically and for screening large groups with various environmental exposures. Because the need for such surveys has been increasing, we compared a computerized mass flow-meter with a conventional water spirometer. The same forced expiration was measured by both instruments in the laboratory and during an occupational survey. Mean values for forced vital capacity (FVC) were 96 cc greater by the automated technique in the laboratory (this equals 2.2% of the value by the conventional method, with a correlation, r, of 0.998) and 97 cc greater in the field (2.3% of the conventional method; r = 0.995). Differences between the two methods in the laboratory and field for forced expiratory volume in one second (FEV 1.0) were +24 cc (0.68%; r = 0.996) and +47 cc (1.6%; r = 0.996) and for forced expiratory flow (FEF)25-75--179cc/sec (4.18%; r = 0.968) and -63 cc/sec (2.1%; r = 0.992), respectively. For FVC and FEV1.0, the differences between paired values were less than or equal to 10% of the value by water spirometry in all instances and less than or equal to 5% in 95.5% and 96% of comparisons, respectively. For FEF 25-75 the differences between paired values were less than or equal to 20% in 97.2% and less than or equal to 10% in 84.7% of comparisons. These findings confirm the validity of the measurements provided by the automated spirometer.

Autoanalysis↗
PubMedDate not supplied

Subacute inhalation toxicity testing with iodoform vapor.

Subacute inhalation experiments were conducted to determine the LC50 value for adult Sprague-Dawley rats exposed to iodoform vapor. Each dose consisted of 5 males and 5 females that were together for a 7-h exposure or sham exposure and then separated for observation over the subsequent 24-h period. The rats were deprived of food and water during actual exposure or sham exposure. Exposures were conducted in a custom-designed 75-l glass chamber. Vapor concentrations were verified in samples taken from the exposure chamber. Under the conditions of the experiments the 7-h LC50 was found to be 183 ppm. The second objective of these experiments was to determine the toxic effect of iodoform vapor on rats exposed for 7 h/d for 7 consecutive days. Three groups of 5 young adult male and 5 female rats were used. One group served as a sham control and the other groups were exposed to 1 and 14 ppm iodoform vapor. No significant differences were noted in food and water intake, urine and feces output, and intestinal transit performance in either exposed group. No remarkable changes were noted in SMA 12/60 blood values for either exposed group. The only histopathological manifestation noted was the presence of mineralized deposits in the medullary renal tubules of some of the rats from the 14-ppm group.

Animals↗
PubMedDate not supplied

Impact of orthoses on the rate of scoliosis progression in children with cerebral palsy.

This study was undertaken to determine the impact of spinal bracing on curve pattern and the rate of progression of neuromuscular scoliosis in children with cerebral palsy. Twenty-one patients were treated with a Wilmington custom-molded orthosis with 23 h a day brace wear for a mean bracing period of 67 months (range, 22-173). Twenty-two patients had a similar follow-up to spinal fusion but had no bracewear. Patients who were braced had a scoliosis that reached a magnitude of 50 degrees at a mean 12.5 years, compared with a mean age of 14 years for those who were not braced (p > 0.05). Spinal orthotics had no impact on scoliosis curve, shape, or rate of progression in spastic quadriplegic patients who were followed-up on fusion. Apical vertebral rotation > 2 (Nash and Moe criteria) is an indicator of impending rapid progression of the scoliosis curve.

Adolescent↗
PubMedDate not supplied

Cross-cultural nursing. A report of faculty collaboration through regional networking.

Healthcare environments increasingly are becoming culturally diverse. A project to incorporate multicultural issues in curricula, identify cross-cultural student learning opportunities, and increase faculty skills in teaching transcultural concepts is described. Through regional networking, faculty members identified barriers to teaching cross-cultural concepts and strategies to address those barriers. Recommendations call for proactive approaches for sharing resources to strengthen cultural dimensions in schools of nursing, particularly in rural areas that lack cultural diversity.

Cooperative Behavior↗
PubMedDate not supplied

The natural history of Klippel-Feil syndrome: clinical, roentgenographic, and magnetic resonance imaging findings at adulthood.

Twenty-two patients (15 women and seven men) with Klippel-Feil syndrome were reviewed at an average age of 35 years (range, 26-57 years). The average age at diagnosis was 9 years (range, birth-32 years). All patients had a clinical neurologic and orthopaedic examination. Ten patients (45%) had abnormal findings on clinical examination, and 15 patients (68%) had at least one complaint that could be related to the syndrome. The roentgenograms were unremarkable in all patients, except for the typical findings of congenital fusion; no vertebral subluxation or stenosis was noted in any patient. The magnetic resonance images revealed degenerative changes in the disks of 100% of the patients, evidenced by a low-intensity signal on the T2-weighted images. Nineteen patients (86%) had abnormal findings on the magnetic resonance imaging scans, including disk protrusion (16 patients), osteophytes (four patients), syringomyelia (four patients), and narrowing at the level of the craniovertebral junction (six patients). Our results confirm the well-held belief that the Klippel-Feil syndrome can cause problems in adult life.

Adult↗
PubMedDate not supplied

A behaviour management course for a group of mothers: the importance of the course setting for effective use of available resources.

Many patients experience difficulty in managing aspects of their young children's behaviour; and yet personnel with the psychological skills to resolve these problems are only available to a small proportion of parents, usually after a period of serious escalation of the difficulties. This article describes an attempt to make economical use of an educational psychologist's time by providing a short course for a volunteer group of mothers whose children attended a pre-school group. The educational orientation of the centre is shown to facilitate the transmission of the required skills and knowledge to the mothers, suggesting both a desirable form of organization for such centres and a specific activity which could profitably take place within them.

Behavior Therapy↗