Search PubMed⌕ Search

Biomedical subjects

R Burns

Publications and source records attributed to R Burns.

At least 37 records · Page 2Linked to original sources
PubMed1999

Structural changes in the actin-myosin cross-bridges associated with force generation induced by temperature jump in permeabilized frog muscle fibers.

Structural changes induced by Joule temperature jumps (T-jumps) in frog muscle fibers were monitored using time-resolved x-ray diffraction. Experiments made use of single, permeabilized fibers that were fully activated after slight cross-linking with 1-ethyl-3-[3-dimethylamino)propyl]carbodiimide to preserve their structural order. After T-jumps from 5-6 to approximately 17 degrees C and then on to approximately 30 degrees C, tension increased by a factor of 1.51 and 1.84, respectively, whereas fiber stiffness did not change with temperature. The tension rise was accompanied by a decrease in the intensity of the (1, 0) equatorial x-ray reflection by 15 and 26% (at approximately 17 and approximately 30 degrees C) and by an increase in the intensity of the M3 myosin reflection by 20% and 41%, respectively. The intensity of the (1,1) equatorial reflection increased slightly. The peak of the intensity on the 6th actin layer line shifted toward the meridian with temperature. The intensity of the 1st actin layer line increased from 12% (of its rigor value) at 5-6 degrees C to 36% at approximately 30 degrees C, so that the fraction of the cross-bridges labeling the actin helix estimated from this intensity increased proportionally to tension from approximately 35% at 5-6 degrees C to approximately 60% at approximately 30 degrees C. This suggests that force is generated during a transition of nonstereo-specifically attached myosin cross-bridges to a stereo-specific binding state.

Actomyosin↗
PubMed1999

Using telehealth interventions to prevent pressure ulcers in newly injured spinal cord injury patients post-discharge. Results from a pilot study.

OBJECTIVE: To determine which of three approaches to care produces the lowest incidence of pressure ulcers, promotes the most effective care of sores that develop, and leads to the fewest hospitalizations in newly injured patients with spinal cord injury after discharge. METHODS: Spinal cord injury patients (n = 12) were recruited for a telehealth intervention after initial injury, and matched cases were recruited for telephone counseling and standard care groups. Patients were monitored for 6-8 months after discharge. RESULTS: The video group had the greatest number of reported and identified pressure ulcers. Differences in health care utilization between the video and telephone telehealth groups were small. The standard care group reported the lowest number of pressure ulcers and lowest frequency of health care utilization. Substantial differences existed in employment rates before and after injury. The video group had the lowest pre-injury rate of employment and the highest post-injury rate of employment. CONCLUSIONS: Tracking pressure ulcer incidence, particularly stage I sores, is difficult. Self-report is likely to lead to substantial underreporting. Similarly, self-report on health care utilization over extended periods may lead to undercounting of encounters. Telehealth interventions appear to improve ulcer tracking and management of all ulcer occurrences. Video interventions may affect outcomes, such as employment rates, which are not conventionally measured.

Adult↗
PubMed1999

Use of telerehabilitation to manage pressure ulcers in persons with spinal cord injuries.

Pressure ulcers are a common and serious secondary complication of spinal cord injury. In addition to being costly and difficult to treat, pressure ulcers may interfere with many aspects of patient and family life, including the ability to meet educational, vocational, and social goals. Treatment of pressure ulcers includes weekly assessment by a clinician, a requirement that often is impossible for clients to meet. In an effort to improve outcomes in wound care treatment, a rehabilitation center undertook an exploratory project to determine whether wound care via telerehabilitation was a viable alternative to clinic visits. Telerehabilitation is the use of telecommunication technology to deliver rehabilitation services at a distance. Eight patients being followed in the outpatient clinic participated in the project. The Picasso Still-Image Videophone was used to capture and send images from the patients' homes to the clinic. Findings from the exploratory study demonstrated that pressure ulcers can be successfully managed via telerehabilitation.

Adult↗
PubMed1998

A computer-assisted system for reconstructing and interpreting the dynamic three-dimensional relationships of the outer surface, nucleus and pseudopods of crawling cells.

Newly developed software additions to the three-dimensional dynamic image analysis system, 3D-DIAS, are described for simultaneously reconstructing and motion analyzing in three dimensions the outer surface, nucleus and pseudopods of living, crawling cells. This new system is then used to describe for the first time a nuclear behavior cycle in translocating Dictyostelium discoideum amoebae and to investigate the role of pseudopod extension in this process. The nuclear behavior cycle is tuned to the two phases of the general cell behavior cycle [Wessels et al., 1994], and includes nuclear migration both in the z- and in the x,y-axes from the proximal border of the prior anterior pseudopod to the proximal border of a newly expanding anterior pseudopod. Nuclear migration is cued by pseudopod-substratum contact, achieves velocities in excess of 50 microm/min, and is accompanied by characteristic changes in nuclear shape. The rules and characteristics of nuclear behavior are demonstrated to be intact in two mutants affecting pseudopod formation, a myosin IB null mutant (myoB-) and a myosin II heavy chain phosphorylation mutant (3XALA). The rules and characteristics of nuclear migration, however, are disrupted upon dissolution of microtubules by colcemid. Together the above results demonstrate that the newly developed 3D-DIAS system can be used to gain new insights into the dynamic changes in the intracellular 3D architecture associated with cellular translocation.

Animals↗
PubMed1998

Functional outcomes of posthospital care for stroke and hip fracture patients under medicare.

BACKGROUND: Medicare's introduction of the Prospective Payment System for hospitals has led to tremendous growth in ways of providing posthospital care. Despite substantial differences in costs per episode of care, the type of posthospital care that produces the best results for specific types of patients is not clear. This study analyzed the outcomes of different types of posthospital care for a cohort of older Medicare patients (who had diagnoses associated with the use of a range of posthospital care modalities) for up to a year after hospital discharge. METHODS: Medicare patients hospitalized with strokes and hip fractures were enrolled consecutively just before discharge from 52 hospitals in three cities in 1988-1989. These diagnosis-related groups were chosen because patients were discharged to all three major types of Medicare-supported posthospital care. Patients were interviewed in-person before discharge and again at 6 weeks, 6 months, and 1 year after discharge. The functional outcomes of posthospital care were evaluated by the instrumental variables estimation approach to correct for selection bias caused by nonrandom treatment assignment. The impacts of discharge locations on the functional outcomes were examined by one-way analyses of variance (ANOVA). RESULTS: In general, the more disabled patients went to nursing homes and rehabilitation, but the overlap in distribution was sufficient to conduct the analyses. Stroke patients discharged to nursing homes had the highest mortality rate (P<.01). Stroke patients discharged to home health had the lowest rehospitalization rates (P<.05). Hip fracture discharged to home health care had the highest adjusted rehospitalization rate, whereas those discharged to nursing homes had the lowest adjusted rehospitalization rate (P<.05). For stroke patients, posthospital care in rehabilitation facilities or home health care was associated with significantly better functional improvement compared with stroke patients discharged elsewhere. However, functional outcomes deteriorated by 1 year posthospitalization among stroke patients who received their posthospital care at nursing homes or received no formal posthospital care. For hip fracture patients, all four types of posthospital care were associated with functional improvement, but patients discharged to rehabilitation facilities experienced the most functional improvement. CONCLUSIONS: The choice of posthospital care can influence the course of Medicare patients. Careful attention should be paid to how hospital discharge decisions are made and to the financial incentives for different types of posthospital care provided under the current payment system. The current supply of nursing homes is not well suited to the demands of posthospital care.

Activities of Daily Living↗
PubMed1998

CD86 (B7-2), but not CD80 (B7-1), expression in the epidermis of transgenic mice enhances the immunogenicity of primary cutaneous Candida albicans infections.

Transgenic (Tg) mice whose epidermal keratinocytes constitutively overexpress either B7-1 (CD80) or B7-2 (CD86) exhibited exaggerated cutaneous delayed type hypersensitivity (DTH) to haptens compared to non-Tg mice. To determine whether enhanced DTH in these Tg mice is seen in response to cutaneous fungal infections, a primary infection with Candida albicans was established by inoculating this organism on the occluded skin of Tg and non-Tg mice. These infections resolved 7 days after removal of occlusive dressing in all three groups of mice, without evidence of exaggerated inflammation in either the Tg or non-Tg mice. Only B7-2 Tg mice developed enhanced Th1-lymphocyte-mediated immune responses to C. albicans antigens after resolving this infection: enhanced footpad swelling in response to intradermal C. albicans antigens, enhanced production of mRNA encoding Th1 lymphokines in draining lymph nodes, and increased gamma interferon secreted into culture supernatants by lymph node T lymphocytes stimulated with Candida antigens in vitro. Lastly, Western blotting of sera from mice that had resolved this fungal infection indicated that only B7-2 Tg mice recognized a wide range of Candida-associated antigens. These data suggest that these two costimulatory molecules, when expressed by keratinocytes, do not deliver identical signals to C. albicans antigen-reactive Th1 lymphocytes. The enhanced immune response in B7-2 Tg mice to a cutaneous C. albicans infection demonstrates the importance of antigen presentation and costimulation in immune reactivity to fungi. Furthermore, B7-2 Tg mice may be useful in identification of protective Candida antigens.

Animals↗
PubMed1998

A feasibility study of video-based home telecare for clients with spinal cord injuries.

We carried out a feasibility study of the use of a home telecare intervention to promote skin and other self-care activities for clients with spinal cord injuries (SCIs) following their discharge from a rehabilitation facility. Eleven clients (mean age 38 years) participated in at least three video-sessions over a minimum of six weeks. The equipment used was a video-phone which could transmit both audio and still images over an ordinary telephone line. Video-sessions were followed by, or interspersed with, telephone calls. There was an average of 10 video-calls (range 3-25) and an average of six telephone calls (range 0-22) per client. The average length of the consultations was 23 min (range 15-34 min). The overall impressions of the 11 clients were very positive. Weekly telecare sessions for four to six weeks, followed by telephone counselling alone every other week for another four weeks, appears to be the appropriate sequence for most SCI clients.

Adolescent↗
PubMed1997

Muscle force is generated by myosin heads stereospecifically attached to actin.

Muscle force is generated by myosin crossbridges interacting with actin. As estimated from stiffness and equatorial X-ray diffraction of muscle and muscle fibres, most myosin crossbridges are attached to actin during isometric contraction, but a much smaller fraction is bound stereospecifically. To determine the fraction of crossbridges contributing to tension and the structural changes that attached crossbridges undergo when generating force, we monitored the X-ray diffraction pattern during temperature-induced tension rise in fully activated permeabilized frog muscle fibres. Temperature jumps from 5-6 degrees C to 16-19 degrees C initiated a 1.7-fold increase in tension without significantly changing fibre stiffness or the intensities of the (1,1) equatorial and (14.5 nm)(-1) meridional X-ray reflections. However, tension rise was accompanied by a 20% decrease in the intensity of the (1,0) equatorial reflection and an increase in the intensity of the first actin layer line by approximately 13% of that in rigor. Our results show that muscle force is associated with a transition of the crossbridges from a state in which they are nonspecifically attached to actin to one in which stereospecifically bound myosin crossbridges label the actin helix.

Actins↗
PubMed1997

A randomized trial comparing aerobic exercise and resistance exercise with a health education program in older adults with knee osteoarthritis. The Fitness Arthritis and Seniors Trial (FAST).

OBJECTIVE: To determine the effects of structured exercise programs on self-reported disability in older adults with knee osteoarthritis. SETTING AND DESIGN: A randomized, single-blind clinical trial lasting 18 months conducted at 2 academic medical centers. PARTICIPANTS: A total of 439 community-dwelling adults, aged 60 years or older, with radiographically evident knee osteoarthritis, pain, and self-reported physical disability. INTERVENTIONS: An aerobic exercise program, a resistance exercise program, and a health education program. MAIN OUTCOME MEASURES: The primary outcome was self-reported disability score (range, 1-5). The secondary outcomes were knee pain score (range, 1-6), performance measures of physical function, x-ray score, aerobic capacity, and knee muscle strength. RESULTS: A total of 365 (83%) participants completed the trial. Overall compliance with the exercise prescription was 68% in the aerobic training group and 70% in the resistance training group. Postrandomization, participants in the aerobic exercise group had a 10% lower adjusted mean (+/- SE) score on the physical disability questionnaire (1.71 +/- 0.03 vs 1.90 +/- 0.04 units; P<.001), a 12% lower score on the knee pain questionnaire (2.1 +/- 0.05 vs 2.4 +/- 0.05 units; P=.001), and performed better (mean [+/- SE]) on the 6-minute walk test (1507 +/- 16 vs 1349 +/- 16 ft; P<.001), mean (+/-SE) time to climb and descend stairs (12.7 +/- 0.4 vs 13.9 +/- 0.4 seconds; P=.05), time to lift and carry 10 pounds (9.1 +/- 0.2 vs 10.0 +/- 0.1 seconds; P<.001), and mean (+/-SE) time to get in and out of a car (8.7 +/- 0.3 vs 10.6 +/- 0.3 seconds; P<.001) than the health education group. The resistance exercise group had an 8% lower score on the physical disability questionnaire (1.74 +/- 0.04 vs 1.90 +/- 0.03 units; P=.003), 8% lower pain score (2.2 +/- 0.06 vs 2.4 +/- 0.05 units; P=.02), greater distance on the 6-minute walk (1406 +/- 17 vs 1349 +/- 16 ft; P=.02), faster times on the lifting and carrying task (9.3 +/- 0.1 vs 10.0 +/- 0.16 seconds; P=.001), and the car task (9.0 +/- 0.3 vs 10.6 +/- 0.3 seconds; P=.003) than the health education group. There were no differences in x-ray scores between either exercise group and the health education group. CONCLUSIONS: Older disabled persons with osteoarthritis of the knee had modest improvements in measures of disability, physical performance, and pain from participating in either an aerobic or a resistance exercise program. These data suggest that exercise should be prescribed as part of the treatment for knee osteoarthritis.

Activities of Daily Living↗
PubMed1996

Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: results from Galileo's initial orbit.

The Near Infrared Mapping Spectrometer performed spectral studies of Jupiter and the Galilean satellites during the June 1996 perijove pass of the Galileo spacecraft. Spectra for a 5-micrometer hot spot on Jupiter are consistent with the absence of a significant water cloud above 8 bars and with a depletion of water compared to that predicted for solar composition, corroborating results from the Galileo probe. Great Red Spot (GRS) spectral images show that parts of this feature extend upward to 240 millibars, although considerable altitude-dependent structure is found within it. A ring of dense clouds surrounds the GRS and is lower than it by 3 to 7 kilometers. Spectra of Callisto and Ganymede reveal a feature at 4. 25 micrometers, attributed to the presence of hydrated minerals or possibly carbon dioxide on their surfaces. Spectra of Europa's high latitudes imply that fine-grained water frost overlies larger grains. Several active volcanic regions were found on Io, with temperatures of 420 to 620 kelvin and projected areas of 5 to 70 square kilometers.

Ammonia↗
PubMed1996

Geriatric medicine.

Explore the source record for details and available documents.

Alzheimer Disease↗
PubMed1996

Use of post-hospital care by Medicare patients.

BACKGROUND: Medicare's introduction of the Prospective Payment System for hospitals has shortened hospital stays and, as a consequence, has increased the use of post-hospital care. Medicare coverage provides for various types of post-hospital care. This paper examines the characteristics of patients, cities, and hospitals associated with discharge to these different types of post-hospital care. METHODS: A Total of 2248 consecutive Medicare patients having one of five diagnosis related groups (DRGs), who were about to be discharged from 52 hospitals in three cities in 1988-1989, were enrolled in the study. These DRGs comprised approximately one-eighth of all Medicare hospital discharges and 40% of all Medicare-paid post-hospital care. Patients were interviewed in person before discharge and again 6 weeks after discharge. Clinical severity measures were developed from information abstracted from each patient's medical record. For each DRG, multinomial logit regression equations were developed to identify factors associated with the choice of one of four possible discharge locations: home with no formal care, home health care, nursing home care, or rehabilitation. RESULTS: Discharge location could be predicted correctly in 52 to 71% of cases, depending on the DRG. This level of predictive accuracy was significantly greater than relying on the modal discharge location, which accounted for 33 to 62% of cases. Most of the predictive power came from information gathered at the discharge interview. The variables associated significantly with the discharge location varied with the DRG and location examined. Living alone and functional dependency at discharge were the significant predictors found most often. CONCLUSIONS: Rather than assuming that everyone is discharged to the modal location, patient discharge location can be predicted. Much of the explanation can be traced to a few variables such as functional status and living situation. The lack of greater accuracy suggests that factors other than those identified as important by clinical panels are involved in discharge planning for Medicare patients.

Activities of Daily Living↗
PubMed1996

Validation of the Short Form 36 (SF-36) health survey questionnaire among stroke patients.

BACKGROUND AND PURPOSE: Few studies have examined the utility of a new generic health status measure, the Short Form 36 health survey questionnaire (SF-36), in stroke patients. Our aim was to test the internal consistency and validity of the SF-36 in a cohort of long-term stroke survivors. METHODS: The Australian version of the SF-36 was tested in 90 consecutive 1-year stroke survivors (mean age, 72 years) identified from our hospital discharge data. The instrument was administered by personal interview. Validity was assessed by comparing patients' scores on the SF-36 with those obtained for the Barthel Index, the 28-item General Health Questionnaire, and the Adelaide Activities Profile, an instrument developed from the Frenchay Activities Index. RESULTS: The SF-36 was relatively quick and easy to use and had satisfactory internal consistency (Cronbach's alpha > 0.7). For all eight SF-36 health scales, the mean scores for patients dependent in self care and with mental ill health were significantly different from patients without these disabilities, but the strength of the differences varied in a predictable manner. However, the SF-36 social functioning scale did not provide a valid measure of everyday activities relevant to many elderly patients as measured by the Adelaide Activities Profile. CONCLUSIONS: The SF-36 avoids the "ceiling effect" of most disability scales and provides a valid measure of physical and mental health after stroke, but it does not appear to characterize well social functioning. Thus, the instrument may need to be supplemented by other measures for a comprehensive assessment of stroke outcome.

Adult↗