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Biomedical subjects

H L Smith

Publications and source records attributed to H L Smith.

At least 19 recordsLinked to original sources
PubMed1995

Vestibulo-ocular reflex (VOR) biases in normal subjects and patients with compensated vestibular loss.

The properties of the vestibulo-ocular reflex (VOR) were examined during sinusoidal passive head rotation in the dark at 1/6 Hz, in 9 normal subjects and 14 unilateral vestibular patients. Rotation speeds ranged from 90 to 180 degrees/s. The bias (offset of slow-phase velocity from zero) and gain in the VOR were estimated by using a polynomial (cubic) fit between head and slow-phase eye velocity, thereby allowing for possible non-linearities in the reflex. The gain in the VOR in this context refers to the linear components of the fit, and so predicts sensitivity only at low head velocities. The aim of the study was to verify previous theoretical predictions that VOR bias could vary with the rotation parameters, that this bias could be used to detect the side of a vestibular lesion even at low frequency rotation, and make non-linearities more obvious. Confirming these predictions, the VOR bias in a given test is never equal to any spontaneous nystagmus, even if present before rotation. The range of values for the gain in the VOR (as defined above) in normals and compensated unilateral vestibular patients overlap, so that they cannot be statistically separated into two response sets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Pharmacology and neurochemistry of nefazodone, a novel antidepressant drug.

Nefazodone is a new antidepressant drug with a pharmacologic profile distinct from that of the tricyclic, monoamine oxidase inhibitor, and serotonin selective reuptake inhibitor antidepressants. Nefazodone was initially discovered for its ability to block 5-HT2A receptors and its reduced potency as an alpha 1-adrenergic blocker. It was later shown to inhibit both serotonin and norepinephrine uptake in vitro, attributes which most likely impart its clinical efficacy and which differentiate nefazodone from its chemical predecessor trazodone. The combination of these two mechanisms may ultimately result in a facilitation of 5-HT1A-mediated neurotransmission, which may be beneficial for treating symptoms of depression as evidenced by recent clinical findings. In addition, the preclinical profile of nefazodone demonstrates that it has decreased anticholinergic and antihistaminic activity relative to traditional agents. Clinical findings to date are consistent with these observations.

Animals↗
PubMed1994

Quality of work life in home care. The contribution of leaders' personal concern for staff.

The process of healthcare restructuring is creating substantial stress for healthcare organizations and professionals. As the health system focuses on issues associated with restructuring, concern for staff may be minimized when nursing administrators and other healthcare leaders address contextual pressures and their impact on service delivery. The authors examine how leaders' personal concern for nurses and homemakers contributes to quality of working life in home health. Strategies aimed at enhancing personal concern for staff are discussed from the perspective of transformational leadership.

Adult↗
PubMed1994

Lower Medicare mortality among a set of hospitals known for good nursing care.

The objective of this study is to investigate whether hospitals known to be good places to practice nursing have lower Medicare mortality than hospitals that are otherwise similar with respect to a variety of non-nursing organizational characteristics. Research to date on determinants of hospital mortality has not focused on the organization of nursing. We capitalize on the existence of a set of studies of 39 hospitals that, for reasons other than patient outcomes, have been singled out as hospitals known for good nursing care. We match these "magnet" hospitals with 195 control hospitals, selected from all nonmagnet U.S. hospitals with over 100 Medicare discharges, using a multivariate matched sampling procedure that controls for hospital characteristics. Medicare mortality rates of magnet versus control hospitals are compared using variance components models, which pool information on the five matches per magnet hospital, and adjust for differences in patient composition as measured by predicted mortality. The magnet hospitals' observed mortality rates are 7.7% lower (9 fewer deaths per 1,000 Medicare discharges) than the matched control hospitals (P = .011). After adjusting for differences in predicted mortality, the magnet hospitals have a 4.6% lower mortality rate (P = .026 [95% confidence interval 0.9 to 9.4 fewer deaths per 1,000]). The same factors that lead hospitals to be identified as effective from the standpoint of the organization of nursing care are associated with lower mortality among Medicare patients.

Analysis of Variance↗
PubMed1994

Determining costs associated with quality in health care delivery.

This article examines the costs associated with quality in health care delivery. A model applicable to health care settings is specified according to investments in quality and the cost of not achieving quality. The premises and basic theories underlying the model are explored. The model was developed at Lovelace Health Systems in Albuquerque, New Mexico, as a decision making tool. The specific cost elements comprising the quality cost model are identified and illustrated using the working model adopted at Lovelace. The managerial impact of the quality cost model and the implications for other health care organizations are examined.

Decision Making, Organizational↗
PubMed1994

Nonreporting of births or nonreporting of pregnancies? Some evidence from four rural counties in north China.

Coale and Banister argue that in China, elevated sex ratios in retrospective surveys are in part a function of collecting birth histories in a culture in which the definition of a birth may exclude mortality shortly after birth: an infant death in the West may be a stillbirth in east Asia. I present data from a recent sample survey featuring a retrospective pregnancy history. These data reveal that at least in the first pregnancy, from which the preponderance of sample births arise, there is no evidence of elevated female infant mortality or of high numbers of stillbirths, but that reported sex ratios are unusually high. The proportion of stillbirths grows for later pregnancies, but not enough to account for high sex ratios. Retrospective fertility data regarding recall over a recent interval are vexed less by a misunderstanding of what a live birth is than by a "misunderstanding" of what a (reportable) pregnancy is.

Abortion, Legal↗
PubMed1993

Reduction of structured population models to threshold-type delay equations and functional differential equations: a case study.

It is shown by way of a simple example that certain structured population models lead naturally to differential delay equations of the threshold type and that these equations can be transformed in a natural way to functional differential equations. The model examined can be viewed as a model of competition between adults and juveniles of a single population. The results indicate the possibility that this competition leads to instability.

Age Factors↗
PubMed1993

Epigastric impedance recording for measuring gastric emptying in children: how useful is it?

Epigastric impedance recording was used to measure gastric half-emptying time (t1/2) of orange squash in 45 healthy infants and children. The relationship between age, body size, and composition and the impedance increase after gastric filling was investigated, together with the effects on half-emptying time of adding fat, increasing viscosity, and increasing osmolality in the test meal. The mean t1/2 for orange squash was 13.5 min. The increase in impedence per unit volume ingested showed a significant inverse relationship with age (r = -0.62, p < 0.001), and with various anthropometric variables (r ranged from -0.48 to -0.80, p < 0.01). No relationship was observed between t1/2 and age, sex, body size, or composition. Addition of 1.25% triglyceride or a 600-fold increase in viscosity of the test meal were both accompanied by a significant lengthening of t1/2 (p = 0.005 and p < 0.001, respectively), but t1/2 did not alter with a fourfold increase in test meal osmolality. The test was well tolerated by all subjects, but its usefulness is limited by susceptibility to movement artefact, and also the necessity to use simple, liquid test meals.

Adolescent↗
PubMed1992

Strategic planning in rural health care organizations.

Is strategic planning associated with higher levels of performance in health care organizations? Is strategic planning effective? This article examines strategic planning's impact on rural hospital and rural nursing facility performance, organizational characteristics, and strategy. The findings suggest that strategic planning in rural hospitals is strongly associated with higher profits, operating margins and planning effectiveness, and associated to a lesser extent with lower costs and higher revenues per patient day. However, strategic planning does not appear to be associated with higher performance in nursing facilities. The implications for strategic planning in rural health care organizations are discussed.

Financial Management↗
PubMed1991

The role of structural symmetry in linearizing ocular reflexes.

This work presents a simulation study using an anatomically relevant model of the vestibulo-ocular reflex (VOR). The aim is to explore the functional properties of a bilateral structure in the premotor circuits of the oculomotor system. The major conclusions using sinusoidal inputs are: A bilateral structure in a sensory-motor system improves its linear range beyond expected central limits, if provided with symmetric interconnections. Given a bilateral (push-pull) sensory arrangement, non-linear sensor characteristics are actually advantageous. The greatest improvement in linear range of the reflex (here VOR) relies on intact sensors on both sides. In the case of a single sensor (unilateral head velocity input), or unmatched bilateral sensors, this study predicts a decrease in the linear range and the appearance of a variable bias. These implications are compatible with available data and can be tested in a clinical environment.

Animals↗
PubMed1991

Assessing neck extension-flexion as a basis for temporomandibular joint dysfunction.

In the August 1987 issue of the Journal of Oral and Maxillofacial Surgery, Weinberg and LaPointe published an article entitled "Cervical Extension-Flexion Injury (Whiplash) and Internal Derangement of the Temporomandibular Joint" in which they proposed an explantation for injury to the temporomandibular joint resulting from certain motor vehicle accidents. In this article, the previous mechanism is assessed and the authors conclude that it is inaccurate.

Acceleration↗
PubMed1991

Responses to prospective payment by rural New Mexico hospitals.

A cross-sectional study is used to determine how rural New Mexico hospitals altered service diversification, inpatient service emphasis, and service promotion during Medicare's prospective payment system (PPS) transition and posttransition phases. Results suggest that the hospitals implemented distinct strategies in response to PPS. The posttransition strategies were examined for their association with improved revenue and utilization indicators. Few of the service diversification and promotional strategies were consistent predictors of performance. Emphasis on fine-tuning inpatient services was the most promising predictor of higher utilization and revenue measures. The implications for other rural hospitals are discussed.

Cross-Sectional Studies↗