Biomedical subjects

S J Bennett

Publications and source records attributed to S J Bennett.

At least 19 recordsLinked to original sources

PubMed2002

Local stability in coordinated rhythmic movements: fluctuations and relaxation times.

An experiment was conducted to examine the stability of the anti-phase and in-phase modes of coordination by means of both fluctuations and relaxation times. Participants (n=6) performed a rhythmic bimanual forearm coordination task that required them to oscillate their forearms in-phase and anti-phase while grasping two manipulanda at fixed frequencies ranging from 0.6 to 1.8 Hz. Relaxation times were measured as the time taken to return to a stable mode following the application of a transient mechanical torque. It was found that relaxation times were not different statistically across participants, frequencies, and coordinative modes. However, fluctuations, as indicated by the mean S.D. of relative phase across individual frequency plateaus, were significantly greater in the anti-phase than in the in-phase mode of coordination, p<0.05. Whilst providing new empirical support for the notion that relaxation times should be of the same order of magnitude at frequencies outside transition regions, the findings suggest that the level of stochastic noise in the anti-phase mode is greater than that of the in-phase mode. Implications are made for the future assessment of local pattern stability.

Adult↗

PubMed2001

Open-label randomized trial of torsemide compared with furosemide therapy for patients with heart failure.

PURPOSE: Because the bioavailability of oral furosemide is erratic and often incomplete, we tested the hypothesis that patients with heart failure who were treated with torsemide, a predictably absorbed diuretic, would have more favorable clinical outcomes than would those treated with furosemide. PATIENTS AND METHODS: We conducted an open-label trial of 234 patients with chronic heart failure (mean [+/- SD] age, 64 +/- 11 years) from an urban public health care system. Patients received oral torsemide (n = 113) or furosemide (n = 121) for 1 year. The primary endpoint was readmission to the hospital for heart failure. Secondary endpoints included readmission for all cardiovascular causes and for all causes, numbers of hospital days, and health-related quality of life. RESULTS: Compared with furosemide-treated patients, torsemide-treated patients were less likely to need readmission for heart failure (39 [32%] vs. 19 [17%], P <0.01) or for all cardiovascular causes (71 [59%] vs. 50 [44%], P = 0.03). There was no difference in the rate of admissions for all causes (92 [76%] vs. 80 [71%], P = 0.36). Patients treated with torsemide had significantly fewer hospital days for heart failure (106 vs. 296 days, P = 0.02). Improvements in dyspnea and fatigue scores from baseline were greater among patients treated with torsemide, but the differences were statistically significant only for fatigue scores at months 2, 8, and 12. CONCLUSIONS: Compared with furosemide-treated patients, torsemide-treated patients were less likely to be readmitted for heart failure and for all cardiovascular causes, and were less fatigued. If our results are confirmed by blinded trials, torsemide may be the preferred loop diuretic for patients with chronic heart failure.

Aged↗

PubMed2001

Social support and health-related quality of life in chronic heart failure patients.

OBJECTIVES: Objectives of this study were to: (1) describe perceived social support during a baseline hospitalization and 12 months later among heart failure patients; (2) examine differences in social support as a function of gender and age (less than 65 and 65 years or older); and (3) examine social support as a predictor of health-related quality of life. BACKGROUND: Social support is a predictor of well-being and mortality, but little is known about support patterns among heart failure patients and how they influence quality of life. METHODS: The sample included 227 hospitalized patients with heart failure who completed the Social Support Survey and the Chronic Heart Failure Questionnaire at baseline; 147 patients completed these questionnaires again 12 months after baseline. RESULTS: Mean baseline and 12-month total support scores were 56 and 53, respectively, with a score of 76 indicating the most positive perceptions of support. The ANOVA indicated significant interactions of gender by age for total (F = 5.04; p = 0.03) and emotional/informational support (F = 4.87; p = 0.03) and for positive social interactions (F = 4.43; p = 0.04), with men under age 65 perceiving less support than men aged 65 and older and women in either age group. Baseline support did not predict 12-month health-related quality of life, but changes in social support significantly predicted changes in health-related quality of life (R2 = 0.14). CONCLUSIONS: Overall, perceptions of support were moderate to high, but there was wide variation in perceptions over time. Men under age 65 reported less support than other groups of patients. Importantly, changes in social support were significant predictors of changes in health-related quality of life.

Aged↗

PubMed2001

Specificity of task constraints and effects of visual demonstrations and verbal instructions in directing learners' search during skill acquisition.

In the present study, the efficacy of visual demonstrations and verbal instructions as instructional constraints on the acquisition of movement coordination was investigated. Fifteen participants performed an aiming task on 100 acquisition and 20 retention trials, under 1 of 3 conditions: a modeling group (MG), a verbally directed group (VDG), and a control group (CG). The MG observed a model intermittently throughout acquisition, whereas the VDG was verbally instructed to use the model's movement pattern. Participants in the CG received neither form of instruction. Kinematic analysis revealed that compared with verbal instructions or no instructions, visual demonstrations significantly improved participants' approximation of the model's coordination pattern. No differences were found in movement outcomes. Coordination data supported the visual perception perspective on observational learning, whereas outcome data suggested that the modeling effect is mainly a function of task constraints, that is, the novelty of a movement pattern.

Adult↗

PubMed2001

Effects of manipulating relative and absolute motion information during observational learning of an aiming task.

In the visual perception perspective of observational learning, the manipulation of relative and absolute motion information in visual demonstrations optimally directs learners' search towards appropriate task solutions. We assessed the effect of emphasizing transformational information and removal of structural information using point-light kinematic displays in approximating the model's relative motion patterns. Participants viewed computer-simulated point-light demonstrations or normal video demonstrations before and intermittently throughout 100 acquisition trials with knowledge of results on an underarm modified-dart aiming task. On the next day, all participants performed 20 retention trials without demonstrations. The kinematics of spatial and temporal coordination and control variables were examined relative to the model's action, as well as performance scores. The results indicated that approximation of the model's spatial and temporal coordination and control patterns was achieved after observation of either type of demonstrations. No differences were found in movement outcomes. In a second experiment, the effects of manipulating absolute motion information by slow-motion demonstrations were examined relative to real-time demonstrations. Real-time demonstrations led to a closer approximation to the model's spatial and temporal coordination patterns and better outcome scores, contradicting predictions that slow-motion displays convey intact relative motion information. We speculate that the effect of visual demonstration speed on action perception and reproduction is a function of task constraints--that is, novelty or familiarity of relative motion of demonstrated activities.

Adult↗

PubMed2001

Multi-segment coordination: fatigue effects.

PURPOSE: The aim of this study was to investigate the segmental coordination of vertical jumps under fatigue. METHODS: Twelve subjects performed maximal countermovement jumps with and without fatigue, which was imposed by maximal continuous jumps in place until their maximal jump height corresponded to 70% of the nonfatigued condition. Video, ground reaction forces, and electromyographic signals were recorded to analyze the segmental coordination of countermovement jumps before (CMJ1) and after (CMJ2) fatigue. The magnitude of joint extension initiation, peak joint angular velocity, and peak net power around the ankle, knee, and hip joints and their respective times were determined. RESULTS: CMJ2 was characterized by a longer contact time, which was accompanied with an earlier movement initiation and several differences (P < 0.05) in the variables used to describe coordination. When the movement duration was normalized with respect to the contact phase duration, the differences between CMJ1 and CMJ2 were not sustained. A consistent pattern was indicated, in which the segmental coordination did not differ between jump conditions. When the magnitude of the muscle activation was set aside, a remarkably consistent muscle activation time was noticed between conditions. CONCLUSIONS: It was indicated that countermovement jumps were performed with a consistent well-timed motion of the segments. A "common drive," which acts without the knowledge of the muscle properties, was suggested as mediating and controlling the muscle activation timing between agonist-antagonist muscle pairs.

Adult↗

PubMed2000

Discriminating the role of binocular information in the timing of a one-handed catch. The effects of telestereoscopic viewing and ball size.

Previous work using prediction-motion tasks has indicated that time-to-contact estimates are based exclusively on binocular information when the approaching object is small. The aim of this study was to examine the influence of object size on the use of binocular information sources in specifying time-to-contact in one-handed catching. Subjects (n = 10) were required to time their grasp to catch different-sized balls (60, 80, and 100 mm in diameter) approaching with a constant spatial trajectory and constant velocity of 2.0 m/s. Binocular information was manipulated with a telestereoscope that increased the individuals' effective interocular separation. Subjects performed six trials with each of the different-sized balls in normal and telestereoscopic viewing conditions. It was found that subjects closed the hand earlier when catching the small and medium balls under telestereoscopic viewing compared with normal viewing; furthermore, that subjects closed their hand earlier for the small and medium balls compared with the large ball under telestereoscopic viewing. With regard to hand aperture, there was an effect of ball size, with the hand being opened to a wider aperture for each increase in ball size. Subjects also opened the hand to a wider aperture when catching the small and medium balls under telestereoscopic viewing. These findings are consistent with the notion of an increased reliance on the use of binocular information when the approaching object is small. Furthermore, they indicate that binocular and monocular sources of information are not used in isolation, but rather in combination to support the timing of one-handed catching.

Adult↗

PubMed2000

Mechanical perturbation of the wrist during one-handed catching.

In the present study, the co-ordination of grasp and transport components of one-handed catching was examined following mechanical perturbations applied to the wrist. Six skilled catchers (mean age = 27.5 years) performed 64 trials in which tennis balls were projected at approximately 8 ms-1. The trial blocks consisted of 10 non-perturbed trials (NPTs) (baseline), and a block of 54 trials of which 20 trials were perturbed. The perturbation was in the form of a resistive force (12 N) applied via a piece of cord attached to a mechanical brake. In baseline trials participants reached maximal wrist velocity closer to the time of hand-ball contact (237 ms +/- 68) than in the perturbed (309 ms +/- 61) condition. Furthermore the wrist velocity profile of five out of six participants exhibited a double peak immediately after a perturbation. However, aperture variables such as the relative moment of final hand closure (approximately 70% of overall movement time) were not typically affected. The stability of grasp and transport coupling for one-handed catching was shown to vary from trial to trial. Skilled performers exploited redundant degrees of freedom in the motor system when faced with a sudden, unexpected change in task constraints.

Adult↗

PubMed2000

Urethral diverticula.

Urethral diverticula are a common cause of chronic genitourinary symptoms in women. They occur in three percent of women overall with higher frequencies in selected populations of symptomatic women. The peak incidence is between the ages of 25-45 but they affect all ages. The classical presentation is with recurrent urinary tract infections and post micturition dribbling but almost any urinary symptom may be a presenting feature. Reported cure rates following surgery approach 70% for recurrent urinary tract infection and almost 100% for local symptoms such as dyspareunia. However, despite this and the availability of effective diagnostic techniques diagnosis is often delayed. This is partly due to a lack of awareness among clinicians and partly because the condition overlaps the traditional territories of gynaecologists and urologists.

Diverticulum↗

PubMed2000

Heart Messages: a tailored message intervention for improving heart failure outcomes.

Heart failure is a major health problem in the United States leading to high rates of mortality and morbidity and impaired quality of life. Assisting patients to improve compliance with their self-care regimen, including medications, dietary sodium restrictions, and self-monitoring (daily weights, edema assessment), may improve these poor outcomes. This article describes the development and initial evaluation of Heart Messages, a theory-based, tailored message intervention to improve compliance with the self-care regimen recommended for patients with heart failure. The project involved four phases, each of which is described in this article. The Heart Messages tailored message intervention program is available in both printed and Web-based formats. In a pilot study and clinical evaluation project, the program was found to be useful for patient education and feasible for implementation. Larger randomized trials are now warranted to evaluate the effectiveness of the intervention in improving compliance with the self-care regimen and thereby improving outcomes among patients with heart failure.

Heart Failure↗

PubMed1999

Timing a one-handed catch. II. Adaptation to telestereoscopic viewing.

A pre-exposure, exposure, post-exposure design was used to assess the adaptation of the timing of a one-handed catch during telestereoscopic viewing. More specifically, it was examined whether the adaptation involved: (1) ignoring binocular sources of information and selecting other information, or (2) a recalibration of the coupling between the effected binocular information and the catching movement, and (3), if it is recalibration, whether it is restricted to the manipulated binocular information. To test these hypotheses, subjects (n=16) were assigned to one of two groups, each group performing three blocks of 15 trials in the dark with only the ball visible. In the exposure condition, both groups were required to catch balls under binocular telestereoscopic viewing. In the pre-exposure and post-exposure conditions, subjects performed under binocular and monocular viewing, respectively. Kinematics of the grasping movement were recorded. It was predicted that, in the case of a selection process, no after effects would occur in the post-exposure condition, whereas, in the case of recalibration, aftereffects would occur. Moreover, if the recalibration is restricted to the manipulated information, only the group that was provided with binocular vision during the pre- exposure and post-exposure conditions would show aftereffects. Significant condition (pre-exposure, exposure, post-exposure) by block (first three trials, last three trials) effects were found for the moments of grasp onset, peak opening velocity and hand closure, indicating that the hand was opened and closed earlier in the first three trials of telestereoscopic viewing. This coincided with an increase in catching failures. In addition, for the moments of hand closure and peak closing velocity, negative aftereffects were found in the post-exposure condition. The hand was closed later in the first three trials after removal of telestereoscope. With respect to the presence of the aftereffects, no differences were found between the groups. It was concluded that adaptation to telestereoscopic viewing in the timing of a one-handed catch is due to the recalibration of the coupling between information and movement, rather than a selection of another source of information. Moreover, it is likely that the recalibration was not restricted to the single, manipulated information. Rather, the recalibration involves multiple binocular and monocular optical and oculomotor sources of information.

Adult↗

PubMed1999

Reforming higher specialist training in the United Kingdom--a step along the continuum of medical education.

OBJECTIVES: The requirement to align the arrangements for postgraduate training in the United Kingdom with those elsewhere in the European Community provided the opportunity to review and reform our arrangements for higher specialist training. This paper describes the case for change--the strengths and deficiencies of the traditional pattern of postgraduate medical training, demographic influences in the medical workforce and the need for a more structural or planned approach to training. CONCLUSIONS: Over the past 5 years substantial progress has been made: the introduction of new regulatory arrangements and a new higher specialist training grade; the development of a managed and flexible system for delivering training to standards set by the Royal Colleges and which can accommodate the needs of those pursuing academic and research medicine; and the opportunity for trainees' progress to be measured against published curricula. The significant programme of change has been underpinned by careful workforce planning and the publication of comprehensive guidance. Significant reform of higher specialist training has been achieved. This paper also makes the case for a more strategic approach to planning and developing medical education across the continuum, from entry to medical school until retirement, which can guide medical education and improve patient care into the next millennium.

Education, Medical, Graduate↗

PubMed1999

Measurement of dyspnea in patients treated with mechanical ventilation.

BACKGROUND: Dyspnea, or difficult breathing, is common in patients receiving mechanical ventilation; however, dyspnea is not routinely or systematically measured. OBJECTIVE: The primary purpose of this methodological study was to evaluate the test-retest reliability of 5 dyspnea rating scales and the criterion validity of 4 dyspnea rating scales in patients receiving mechanical ventilation. The secondary purpose was to examine the correlations between each of these 5 rating scales and physiological measures of respiratory function. METHODS: The convenience sample consisted of 28 patients on mechanical ventilation during their hospitalization in the intensive care units of a large, inner-city hospital. Patients rated their dyspnea twice at 30-minute intervals on the visual analogue scale, the vertical analogue dyspnea scale, the modified Borg scale, the numerical scale, and the faces scale. Test-retest reliability was computed by using the intraclass correlation coefficient. Criterion validity was evaluated by using the Spearman rank-order correlation coefficient. RESULTS: The 5 rating scales had acceptable test-retest reliabilities, with intraclass correlation coefficients ranging from 0.81 to 0.97. Criterion validity of the 4 scales also was acceptable, with Spearman rank-order correlation coefficients from 0.76 to 0.96. The rating scales were not correlated with most of the physiological variables. At least half of the patients reported moderate to severe dyspnea. CONCLUSION: The scales showed acceptable reliability and validity, and they will be useful in quantifying dyspnea experienced by patients receiving mechanical ventilation. Further work is needed to evaluate the extent and the severity of dyspnea in such patients in order to evaluate the effectiveness of interventions.

Adult↗

PubMed1998

Characterization of the precipitants of hospitalization for heart failure decompensation.

BACKGROUND: The model for management of patients with heart failure may be a key determinant of morbidity and quality of life. Development of a better management strategy for these patients requires determination of the reasons for decompensation that leads to hospitalization. OBJECTIVES: To ascertain and rank the principal reasons for hospitalization of patients who have heart failure. METHODS: Retrospective audit of all 1992 admissions (N = 1031; 691 patients) coded for heart failure at a Veterans Affairs medical center and a tertiary care university medical center. RESULTS: The diagnosis of heart failure was verified by preset criteria in 72% of the patients. Of the 496 patients with documented heart failure, worsening heart failure was a main reason for admission in 390 (79%). Despite different socioeconomic backgrounds, excessive sodium retention was the leading factor (55%) associated with decompensation in patients at both institutions. Other factors precipitated admission much less often. CONCLUSIONS: Many hospitalizations for heart failure might be avoided by case management directed at lessening sodium overload. Increased use of medications known to be effective in persons with heart failure (angiotensin-converting enzyme inhibitors, digoxin, and adequate diuretic therapy) might reduce the likelihood of decompensation. Implementation of behavioral interventions to assist patients with self-monitoring signs of sodium retention and to improve compliance with medications and dietary sodium restrictions are strategies for further reducing the risk of decompensation.

Aged↗

PubMed1997

Psychosocial variables and hospitalization in persons with chronic heart failure.

Persons with chronic heart failure (HF) must cope not only with the physical impairment of their disease but with the associated emotional distress. The primary purpose of this prospective study was to examine whether the psychosocial variables of symptom impact measured at baseline--health perception, social support and coping--differed between a group of adults with chronic HF who were hospitalized and a group who were not hospitalized during the following six months of the study. A secondary purpose was to examine indices of left ventricular dysfunction that might influence hospitalization. Within the six-month period following baseline data collection, 23 of 62 (37%) patients who completed the study were hospitalized at least once for problems pertaining to HF. Patients in the hospitalized group reported significantly more baseline symptom impact, particularly in the areas of emotional symptoms and deficits of attention and memory. Social support and coping did not differ significantly between hospitalized and nonhospitalized patients. Extent of myocardial dysfunction, age and demographic variables were not significantly different between the two groups. Heart failure decompensation requiring inpatient management was presaged by increased anxiety and disorders of mentation, suggesting that health care providers need to be sensitive to these reported symptoms and their impact, because they might be clues to impending hospitalization.

Adaptation, Psychological↗

PubMed1993

Relationships among selected antecedent variables and coping effectiveness in postmyocardial infarction patients.

Selected theoretical relationships from Lazarus' (1966) model of stress were tested in a convenience sample of 81 postmyocardial infarction clients. Two hypothesized causal models were analyzed. Results from regression analyses indicated 63% of the variance in coping effectiveness was explained by marital status, length of time since hospitalization, perceived availability of social support, uncertainty, degree of threat, coping strategies, and emotions. A revised model that fit the data was proposed. Findings indicated that emotions were an outcome of threat, not coping; threat did not directly affect coping strategies; and coping strategies did not directly influence coping effectiveness.

Adaptation, Psychological↗

PubMed1993

Complications of transvaginal ultrasound-directed follicle aspiration: a review of 2670 consecutive procedures.

PURPOSE: Complications following transvaginal ultrasound-directed follicle aspiration are rare, making it difficult to assess their true incidence. During a 4-year prospective study the complications arising from a series of 2670 consecutive procedures were monitored. RESULTS: Vaginal hemorrhage occurred in 229 (8.6%) of the cases, with a significant loss (> 100 ml) in 22 (0.8%). Postoperative pelvic infection occurred in 18 (0.6%) of the cases. Hemorrhage from the ovary with hemoperitoneum formation was seen on two occasions and necessitated emergency laparotomy in one instance. A single case of pelvic haematoma formation from a punctured iliac vessel was also recorded; this settled without intervention. Of the 18 cases with infection, 9 were severe with pelvic abscess formation; microbiological examination of the pus from these cases suggests that the most common route of infection in such cases is probably by direct inoculation of vaginal organisms into the peritoneal cavity by the collecting needle. CONCLUSION: The low incidence of pelvic infection questions the value of using prophylactic antibiotics. No increased risk of infection was demonstrated in cases with preexisting peritoneal damage.

Abscess↗

PubMed1992

The effects of lignocaine on human sperm motility.

OBJECTIVE: The purpose of this study was to assess the motility of human sperm incubated with various concentrations of lignocaine. METHODS: Eleven semen samples with a sperm density greater than or equal to 20 x 10(6) ml and progressive motility greater than or equal to 40% were prepared using a swim-up technique. Aliquots from each sample were incubated for 4 hr under capacitating conditions with lignocaine concentrations of 100, 10, 1, and 0.1 microgram/ml and without additional lignocaine as a control. Digital computerized motion analysis was performed on all samples at 1, 2, and 4 hr after the addition of lignocaine. RESULTS: After 2 hr of incubation a significant (P less than 0.05) increase in the percentage of sperm with a curvilinear velocity greater than 100 microns/sec was observed in those samples incubated with 100 micrograms/ml lignocaine. This stimulatory effect was no longer apparent after a further 2 hr of incubation. No other significant changes were identified in any of the motility parameters examined. CONCLUSIONS: No adverse effects on human sperm motility were identified during incubation with low concentrations of lignocaine. A transient stimulatory effect was observed at a lignocaine concentration of 100 micrograms/ml.

Humans↗