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Biomedical subjects

S E Davis

Publications and source records attributed to S E Davis.

At least 19 recordsLinked to original sources
PubMed1999

Representational momentum in children: dynamic information and analogue representation.

Two groups of children and a control group of adults completed a visual memory task previously shown to produce representational momentum in adults. In the task, a computer-animated target was shown moving either horizontally or vertically, and the target vanished without warning. After the target vanished, observers indicated the location at which it had vanished. Both children and adults exhibited representational momentum, i.e., indicated locations slightly beyond where the target actually disappeared, and the magnitude of representational momentum was larger for younger children than adults. Implications of the results for issues of sensitivity to dynamics and for reliance on analogue representation are discussed.

Adult↗
PubMed1998

The effect of training and epinephrine infusion on ratings of perceived exertion (RPE).

Seven untrained males (mean age [+/-SD] = 25.6+/-3.9 yr, mean ht = 177.0+/-5.9 cm, mean wt = 65.8+/-7.4 kg) completed a 6-week exercise program (cycle ergometer). Prior to training, and at the end of each week of training, each subject performed a 20 min constant-power exercise test (absolute power was the same each week). At the end of the six week training program (within a few days), an additional 20 min constant-power test was performed, during which epinephrine was infused at a rate of 100 ng x kg(-1) x min(-1) over the final 10 min of exercise. Training significantly (P<0.05) reduced end-exercise ratings of perceived exertion (RPE), plasma epinephrine concentration [Epi], plasma norepinephrine concentration [NE], blood lactate concentration [La-], minute ventilation (V(E)), heart rate (HR), and blood glucose concentration [Glc]. Epinephrine infusion failed to increase RPE despite significant (p < 0.05) increases in [Epi], [La-], V(E) and [Glc]. Therefore, the present data indicate that RPE during exercise is not causally related to changes in plasma [Epi]. It also appears that modest changes in plasma [NE], blood [La-], V(E) and blood [Glc] during constant-power cycle ergometry (as observed during Epi infusion) do not impact RPE.

Adrenergic Agonists↗
PubMed1998

Self-reported use of an implanted FES hand system by adolescents with tetraplegia.

The Freehand System, an eight-channel functional electrical stimulation (FES) system, was implanted in five adolescents with C-5 or C-6 tetraplegia to provide stimulated lateral pinch and palmar grasp. Following completion of inpatient training on how to use the Freehand System for predefined and self-selected activities of daily living (ADL), the adolescents were discharged to use their Freehand systems at home and school. A telephone survey was administered on a weekly basis to obtain information on the type of ADL performed with the Freehand System, reasons for not using the Freehand System, and perceived barriers and motivators to FES use. Twenty surveys were obtained on each adolescent, resulting in a total of 100 surveys. The most common type of activity performed with the Freehand System was self-care, which included tasks such as eating, grooming, and brushing teeth. The Freehand System was also used for productivity activities defined as writing, socialization, and manipulation of school and household objects. Motivators to Freehand System use included perceived need and importance to perform an ADL in an independent fashion, physical ease of using the Freehand System, and availability of social supports that facilitated Freehand System use. While there were several reported barriers to Freehand System use, incompatibility with multiple transfers to and from the wheelchair and lack of physical assistance during morning care to don the system were perceived as two of the more common reasons for nonuse.

Activities of Daily Living↗
PubMed1997

An examination of the clinical validity of the MCMI-III Depressive Personality scale.

We examined the redundancy and incremental validity of the newly introduced Million Clinical Multiaxial Inventory-III (MCMI-III) Depressive Personality scale with a heterogeneous sample of 283 psychiatric inpatients. Linear and nominal bivariate correlations indicated sizable overlap between the MCMI-III Depressive, Avoidant, and Self-Defeating Personality scales. Also, the Depressive Personality scale showed moderate overlap with the MCMI-III Major Depression scale. Despite this redundancy, the Depressive Personality scale made significant independent contributions in predicting Axis-I measures of depression, i.e., the Brief Symptom Inventory (BSI) Depression and Interpersonal Sensitivity scales, as well as the MCMI-III Major Depression scale. The Depressive Personality scale appears to be dimensionally related to these measures of Axis-I depression.

Adolescent↗
PubMed1997

Implanted functional electrical stimulation hand system in adolescents with spinal injuries: an evaluation.

OBJECTIVE: To study the utility and functional benefits of an implanted functional electrical stimulation (FES) system for hand grasp and release in adolescents with tetraplegia secondary to spinal cord injuries. DESIGN: Intervention study with before-after trial measurement with each subject as his or her own control. SETTING: Nonprofit pediatric orthopedic rehabilitation facility specializing in spinal cord injury. PARTICIPANTS: A convenience sample of five adolescents between 16 and 18 years of age with C5 or C6 level tetraplegia at least 1 year after traumatic spinal cord injury. Key muscles for palmar and lateral grasp and release were excitable by electrical stimulation. INTERVENTIONS: A multichannel stimulator/receiver and eight electrodes were surgically implanted to provide stimulated palmar and lateral grasp and release. In conjunction with implantation of the FES hand system, surgical reconstruction in the form of tendon transfers, tendon lengthenings and releases, and joint arthrodeses was performed to augment stimulated hand function. Rehabilitation of the tendon transfers and training in the use of the FES hand system were provided. MAIN OUTCOME MEASURES: Measurements of pinch and grasp force, the Grasp and Release Test (GRT), and an assessment of six activities of daily living (ADL) were administered before implantation of the FES hand system and at regular follow-up intervals. Results of the stimulated response of individual muscles and surgical reconstruction were evaluated using standard and stimulated muscle testing techniques and standard assessment of joint range of motion. All subjects completed followup testing. RESULTS: Lateral and palmar forces were significantly greater than baseline forces (p = .043). Heavy objects on the GRT could only be manipulated with FES, and FES increased the level of independence in 25 of 30 ADL comparisons (5 subjects, 6 activities) as compared to baseline. After training, FES was preferred in 21 of 30 comparisons over the typical means of task completion. Of the 40 electrodes implanted, 37 continue to provide excellent stimulated responses and all of the implanted stimulators have functioned without problems. The surgical reconstruction procedures greatly enhanced FES hand function by either expanding the workspace in which to utilize FES (deltoid to triceps transfer), stabilizing the wrist (brachioradialis to wrist extensor transfer), or stabilizing joints (intrinsic tenodesis transfer, FPL split transfer). CONCLUSION: For five adolescents with tetraplegia, the combination of FES and surgical reconstruction provided active palmar and lateral grasp and release. Laboratory-based assessments demonstrated that the FES system increased pinch force, improved the manipulation of objects, and typically increased independence in six standard ADL as compared to pre-FES hand function. The study also showed that the five adolescents generally preferred FES for most of the ADL tested. Data on the benefits of the implanted FES hand system outside of the laboratory are needed to understand the full potential of FES.

Activities of Daily Living↗
PubMed1997

Exercise training decreases the growth hormone (GH) response to acute constant-load exercise.

To assess the influence of exercise training on the growth hormone (GH) response to acute exercise, six untrained males completed a 20-min, high-intensity, constant-load exercise test prior to and after 3 and 6 wk of training (the absolute power output (PO) during each test remained constant x PO = 182.5 +/- 29.5 W). Training increased (pre- vs post-training) oxygen uptake (VO2) at lactate threshold (1.57 +/- 0.33 L.min-1 vs 1.97 +/- 0.24 L.min-1 P < or = 0.05). VO2 at 2.5 mM blood lactate concentration ([HLa]) (1.83 +/- 0.38 L.min-1 vs 2.33 +/- 0.38 L.min-1, P < or = 0.05), and VO2peak (3.15 +/- 0.54 L.min-1 vs 3.41 +/- 0.47 L.min-1, P < or = 0.05). Power output at the lactate threshold (PO-LT) increased with training from 103 +/- 28 to 132 +/- 23W (P < or = 0.05). Integrated GH concentration (20 min exercise + 45 min recovery) (microgram.L-1 x min) after 3 wk (138 +/- 106) and 6 wk (130 +/- 145) were significantly lower (P < or = 0.05) than pre-training (238 +/- 145). Plasma epinephrine and norepinephrine responses to training were similar to the GH response (EPI-pre-training = 2447 +/- 1110; week 3 = 1046 +/- 144; week 6 = 955 +/- 322 pmol.L-1; P < or = 0.05; NE pre-training = 23.0 +/- 5.2; week 3 = 13.4 +/- 4.8; week 6 = 12.1 +/- 6.8 nmol.L-1; P < or = 0.05). These data indicate that the GH and catecholamine response to a constant-load exercise stimulus are reduced within the first 3 wk of exercise training and support the hypothesis that a critical threshold of exercise intensity must be reached to stimulate GH release.

Adult↗
PubMed1995

Slow component of O2 uptake during heavy exercise: adaptation to endurance training.

Seven untrained male subjects [age 25.6 +/- 1.5 (SE) yr, peak O2 uptake (VO2) 3.20 +/- 0.19 l/min] trained on a cycle ergometer 4 days/wk for 6 wk, with the absolute training workload held constant for the duration of training. Before and at the end of each week of training, the subjects performed 20 min of constant-power exercise at a power designed to elicit a pronounced slow component of VO2 (end-exercise VO2-VO2 at minute 3 of exercise) in the pretraining session. An additional 20-min exercise bout was performed after training at this same absolute power output during which epinephrine (Epi) was infused at a rate of 100 ng.kg-1.min-1 between minutes 10 and 20. After 2 wk of training, significant decreases in VO2 slow component, end-exercise VO2, blood lactate ([La-] and glucose concentrations, plasma Epi ([Epi]) and norepinephrine concentrations, ventilation (VE), and heart rate (HR) were observed (P < 0.05). Although the rapid attenuation of the VO2 slow component coincided temporally with reductions in plasma [Epi], blood [La-], and VE, the infusion of Epi after training significantly increased plasma [Epi] (delta 2.22 ng/ml), blood [La-] (delta 2.4 mmol/l) and VE (delta 10.0 l/min) without any change in exercise VO2. We therefore conclude that diminution of the VO2 slow component with training is attributable to factors other than the reduction in plasma [Epi], blood [La-] and VE.

Adaptation, Physiological↗
PubMed1994

Catecholamine and blood lactate responses to incremental rowing and running exercise.

Ten collegiate rowers performed discontinuous incremental exercise to their tolerable limit on two occasions: once on a rowing ergometer and once on a treadmill. Ventilation and pulmonary gas exchange were monitored continuously, and blood was sampled from a venous catheter located in the back of the hand or forearm for determination of blood lactate ([La]) and plasma epinephrine ([Epi]) and norepinephrine ([NE]) concentrations. Thresholds for lactate (LT), epinephrine (Epi-T), and norepinephrine (NE-T) were determined for each subject under each condition and defined as breakpoints when plotted as a function of O2 uptake (VO2). For running, LT (3.76 +/- 0.18 l/min) was lower (P < 0.05) than Epi-T (4.35 +/- 0.14 l/min) and NE-T (4.04 +/- 0.19 l/min). For rowing, LT (3.35 +/- 0.16 l/min) was lower (P < 0.05) than Epi-T (3.72 +/- 0.22 l/min) and NE-T (3.70 +/- 0.18 l/min) and was lower (P < 0.05) than LT for running. Within each mode of exercise, Epi-T and NE-T did not differ. Because LT occurred at a significantly lower VO2 than either Epi-T or NE-T, we conclude that catecholamine thresholds, per se, were not the cause of LT. However, for both modes of exercise LT occurred at a plasma [Epi] of approximately 200-250 pg/ml (rowing, 221 +/- 48 pg/ml; running, 245 +/- 45 pg/ml); these concentrations are consistent with the plasma [Epi] reported necessary for eliciting increments in blood [La] during Epi infusion at rest. Plasma [NE] at LT differed significantly between modes (rowing, 820 +/- 127 pg/ml; running, 1,712 +/- 217 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Severe obesity: effects on foot mechanics during walking.

The purpose of our study was to determine the effects of severe obesity on the foot mechanics of adult females. Twenty-nine adult females between the ages of 20 and 48 years volunteered as subjects for this investigation. The subjects were separated into a severely obese (O) group (body mass index = 41.14 +/- 2.61; N = 16) and a normal weight control group (body mass index = 20.84 +/- 0.47; N = 13). A Locam camera (100 Hz) positioned perpendicular to the subjects' posterior aspect was used to film the rearfoot movement of the subjects during the final 15 sec of a 10 min treadmill walk. The O group had a significantly greater touchdown angle (P = .05), more total eversion range of motion (P = .001), and a faster maximum eversion velocity (P < .001). Moreover, analysis of dynamic foot angles indicated that the O group had significantly (P = .003) more forefoot abduction. Finally, anthropometric data revealed statistically different (P < .001) Q angle measurements between the O and control groups. The results of this study suggest that severely obese females have significantly greater rearfoot motion, foot angle, and Q angle values than normal weight females.

Activities of Daily Living↗
PubMed1994

The impact of a grief workshop for pediatric oncology nurses on their grief and perceived stress.

Coping with the death of a pediatric patient with whom the nurses has developed a close relationship is reported by nurses as the most stressful experience of being a pediatric nurse. Such losses are inevitable for a pediatric nurse regardless of subspecialty and can contribute to a nurse leaving the specialty or the discipline. To prevent those consequences, nurses' grief needs to be acknowledged, and their grieving needs to be facilitated. The purpose of this study was to determine the impact of a grief workshop on grief symptoms and perceived stress in two groups of pediatric oncology nurses who differed in years of experience in the specialty. Study findings indicated that the workshop affected the two groups differently, with the more experienced nurses reporting significantly higher stress levels after the workshop than did the less experienced nurses. Study findings are interpreted and recommendations for future work are offered.

Adaptation, Psychological↗
PubMed1993

Cardiovascular responses in black and white males during exercise.

Previous investigations have shown blacks to have a significantly lower resting heart rate (HR) compared with whites. Our purpose was to determine if this difference exists during submaximal exercise and to compare other cardiovascular responses during submaximal exercise in black and white males. Sixteen black and 16 white males matched on age, body surface area, and maximal O2 consumption exercised at 0, 50, and 100 W on a cycle ergometer. HR, O2 consumption, and cardiac output via CO2 rebreathing were measured at rest and at each work rate. Stroke volume was then calculated. O2 consumption was not significantly different between blacks and whites at rest or at work rates of 0, 50, or 100 W. Cardiac output increased from rest with 0, 50, and 100 W work for both blacks and whites (6.1 to 13.0, 14.4, and 16.9 l/min and 5.7 to 12.2, 14.3, and 16.3 l/min, respectively). The differences in cardiac output between blacks and whites at rest and all work rates were not statistically significant. At rest and work rates of 0, 50, and 100 W, HR was significantly lower in blacks compared with whites (71, 99, 108, and 119 beats/min vs. 80, 107, 114, and 127 beats/min, respectively). The lower HR in blacks compared with whites was accompanied by a trend toward a higher stroke volume at rest and work rates of 0, 50, and 100 W (85.2, 130.3, 134.7, and 142.9 ml vs. 72.5, 114.9, 126.4, and 127.4 ml, respectively). No differences in resting blood pressures were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Morbidity associated with prenatal disruption of the dividing membrane in twin gestations.

We report eight cases of intrauterine rupture of the dividing membranes in diamniotic twin gestations and the resulting perinatal morbidity and mortality. The poor outcomes associated with these intrauterine amniotic ruptures included fetal and neonatal death secondary to cord entanglement, preterm rupture of the membranes, preterm labor and delivery, and amniotic band syndrome. The overall perinatal mortality rate was 44% (seven of 16), and the mean gestational age at delivery was 29 weeks (range 22-34). Possible etiologies for this intrauterine diamniotic rupture include fetal trauma to the dividing membranes, amniocentesis, infection, and developmental disturbances. A new theory is examined to explain the surviving twin's morbidity associated with intrauterine death of the co-twin. This study suggests that intrauterine rupture of diamniotic twin membranes carries a perinatal mortality consistent with that of true monoamniotic gestations and that, in fact, this entity may be more common than previously thought. Finally, a suspected monoamniotic gestation cannot be ruled out by the historic presence of a dividing membrane on previous ultrasound examination.

Adolescent↗
PubMed1991

Etiologic factors associated with patellofemoral pain in runners.

The purpose of this study was to extend our knowledge of running related injuries by determining whether relationships exist between selected anthropometric, biomechanical, muscular strength and endurance, and training variables and runners afflicted with patellofemoral pain (PFP). Specifically, the objectives of this study were to examine differences in selected measures between a non-injured control group (C) of runners (N = 20) and a group of injured runners (INJ) diagnosed by an orthopedic surgeon as having PFP (N = 16). High speed photography, a force platform, and isokinetic dynamometry were used to determine rearfoot motion, ground reaction forces, and knee muscular strength and endurance. Stepwise discriminant function analyses were performed on the anthropometric, biomechanical, and muscular strength and endurance variables. Q angle was a significant discriminator (P less than 0.01) between the INJ and C groups. The muscular endurance data revealed several significant discriminators with the INJ subjects being weaker in knee extension endurance. Kinetic analysis revealed several significant discriminators whereas rearfoot movement variables were not good discriminators between the groups. The training data revealed that the INJ group ran significantly less (P less than 0.01) miles.wk-1 than the C group. Our results suggest that Q angle is a strong discriminator between runners afflicted with PFP and non-injured runners. In addition, several muscular endurance and kinetic variables may also be important components of the etiology of PFP.

Adolescent↗
PubMed1991

Perinatal outcome following improvement of abnormal umbilical artery velocimetry.

Umbilical artery velocimetry was investigated to determine whether abnormal flow patterns improved with bed rest and if the prognosis of the pregnancy was different in the improved groups. Abnormal flow waveform was defined as a systolic-diastolic ratio (S/D) above the 95th percentile of established normal values. One hundred twenty-eight women had abnormal waveforms. They were placed on bed rest in the left lateral position and monitored by biophysical profile and growth indices. Sixty-six subjects (51.5%) reverted to normal flow waveforms following bed rest, at a mean (+/- SD) interval of 4.5 +/- 1.5 weeks (range 3-10), and 62 (48.5%) exhibited persistent abnormal flow. None of the improved group exhibited fetal distress or perinatal mortality, whereas in the group with persistent abnormal flow, 15 (24%) experienced fetal distress and 13% experienced perinatal mortality. The diagnosis-to-delivery interval in the improved group was 63 +/- 14 days, versus 26 +/- 21 days in the unimproved group, and the mean gestational age at delivery was 37.3 +/- 2.0 versus 32.8 +/- 3.6 weeks, respectively (P less than .0001). We conclude that a subset of patients with abnormal Doppler velocimetry findings will improve on bed rest and have a better perinatal outcome, whereas persistence of abnormal flow defines a group of patients who are at risk for poor perinatal outcome and who require intensive monitoring and intervention.

Bed Rest↗
PubMed1990

Improving the outcome of cervical cerclage by sonographic follow-up.

A total of 39 patients with the diagnosis of cervical incompetence were followed up with cervical sonography after placement of prophylactic McDonald cerclage. During the first year of study, 3 out of 12 patients treated with prophylactic cerclage demonstrated funneling of the internal cervical os when examined with cervical sonography; all 3 had premature deliveries. During the last 3 years of the study, 8 of 27 patients treated with prophylactic cerclage demonstrated funneling. With active intervention, neonatal survival improved to 100%. Sonography aids in the management of patients with cervical incompetence and improves outcome even after placement of cervical cerclage.

Adult↗
PubMed1990

Restructuring support staff classification levels for academic health sciences library positions.

Nonprofessional library support staff traditionally hold what are considered to be low-paying, nonchallenging positions. These negative factors make retaining creative and productive employees difficult. This article outlines the approach taken at the Medical College of Georgia's Robert B. Greenblatt, M.D. Library to devise a structure of library staff positions that becomes progressively more demanding. A new nine-level Library Staff Classification Plan resulted. This plan also enables and encourages employees to acquire more skills and to accept more responsibility in order to qualify for higher-level library positions or to advance their present position to receive comparable rewards. The plan expresses the level of responsibilities expected, the employee qualifications desired, and lists representative duties across the spectrum of typical library tasks.

Georgia↗