Biomedical subjects

R Whipple

Publications and source records attributed to R Whipple.

At least 19 recordsLinked to original sources

PubMed2005

PAN-811 (3-aminopyridine-2-carboxaldehyde thiosemicarbazone), a novel neuroprotectant, elicits its function in primary neuronal cultures by up-regulating Bcl-2 expression.

Neurotoxicity in primary neurons was induced using hypoxia/hypoglycemia (H/H), veratridine (10microM), staurosporine (1microM) or glutamate (100microM), which resulted in 72%, 67%, 75% and 66% neuronal injury, respectively. 3-Aminopyridine-2-carboxaldehyde thiosemicarbazone (PAN-811; 10microM; Panacea Pharmaceuticals, Gaithersburg, MD) pretreatment for 24 h provided maximal neuroprotection of 89%, 42%, 47% and 89% against these toxicities, respectively. Glutamate or H/H treatment of cells increased cytosolic cytochrome c levels, which was blocked by pretreatment of cells with PAN-811. Pretreatment of neurons with PAN-811 produced a time-dependent increase in the protein level of Bcl-2, which was evident even after glutamate or H/H treatments. An up-regulation in the expression of the p53 and Bax genes was also observed following exposure to these neurotoxic insults; however, this increase was not suppressed by PAN-811 pretreatment. Functional inhibition of Bcl-2 by HA14-1 reduced the neuroprotective efficacy of PAN-811. PAN-811 treatment also abolished glutamate or H/H-mediated internucleosomal DNA fragmentation.

Animals↗

PubMed2001

Lower standing systolic blood pressure as a predictor of falls in the elderly: a community-based prospective study.

OBJECTIVES: We investigated prospectively the relationships among falls, physical balance, and standing and supine blood pressure (BP) in elderly persons. BACKGROUND: Falls occur often and adversely affect the activities of daily living in the elderly; however, their relationship to BP has not been clarified thoroughly. METHODS: A total of 266 community-dwelling elderly persons age 65 years or over (123 men and 143 women, mean age of 76 years) were selected from among residents of Coop City, Bronx, New York. Balance was evaluated at baseline using computerized dynamic posturography (DPG). During a one-year follow-up, we collected information on subsequent falls on a monthly basis by postcard and telephone follow-up. RESULTS: One or more falls occurred in 60 subjects (22%) during the one-year follow-up. Women fell more frequently than men (28% vs. 16%, p < 0.03), and fallers were younger than nonfallers. Fallers (n = 60) had lower systolic BP (SBP) levels when compared with nonfallers (n = 206) (128 +/- 17 vs. 137 +/- 22 mm Hg for standing, p < 0.006; 137 +/- 16 vs. 144 +/- 22 mm Hg for lying, p < 0.02), whereas diastolic BP was not related to falls. Falls occurred 2.8 times more often in the lower BP subgroup (<140 mm Hg for standing SBP) than in the higher BP subgroup (> or =140 mm Hg, p < 0.0003), and gender-related differences were observed (p = 0.006): 3.4 times for women (p < 0.0001) versus 1.9 times for men (p = 0.30). Loss of balance, as detected by DPG, did not predict future falls and was also not associated with baseline BP levels. Multiple logistic regression analysis demonstrated that female gender (relative risk [RR] = 2.1, p = 0.02), history of falls (RR = 2.5, p = 0.008) and lower standing SBP level (RR = 0.78 for 10 mm Hg increase, p = 0.005) were independent predictors of falls during one year of follow-up. CONCLUSIONS: Lower standing SBP, even within normotensive ranges, was an independent predictor of falls in the community-dwelling elderly. Elderly women with a history of falls and with lower SBP levels should have more attention paid to the prevention of falls and related accidents.

Accidental Falls↗

PubMed2000

Reliability and responsiveness of two physical performance measures examined in the context of a functional training intervention.

BACKGROUND AND PURPOSE: The reliability and responsiveness of 2 physical performance measures were assessed in this nonrandomized, controlled pilot exercise intervention. SUBJECTS: Forty-five older individuals with mobility impairment (mean age=77.9 years, SD=5.9, range=70-92) were sequentially assigned to participate in an exercise program (intervention group) or to a control group. METHODS: The intervention group performed exercise 3 times a week for 12 weeks that targeted muscle force, endurance, balance, and flexibility. Outcome measures were the 8-item Physical Performance Test (PPT-8) and the 6-minute walk test. Test-retest reliability and responsiveness indexes were determined for both tests; interrater reliability was measured for the PPT-8. RESULTS: The intraclass correlation coefficient for interrater reliability for the PPT-8 was. 96. Intraclass correlation coefficients for test-retest reliability were.88 for the PPT-8 and.93 for the 6-minute walk test. The intervention group improved 2.4 points and the control group improved 0.7 point on the PPT-8, as compared with baseline measurements. There was no change in 6-minute walk test distance in the intervention group when compared with the control group. The responsiveness index was.8 for the PPT-8 and.6 for the 6-minute walk test. CONCLUSION AND DISCUSSION: Measurements for both the PPT-8 and the 6-minute walk test appeared to be highly reliable. The PPT-8 was more responsive than the 6-minute walk test to change in performance expected with this functional training intervention.

Aged↗

PubMed1999

Stance perturbation-evoked potentials in old people with poor gait and balance.

OBJECTIVE: Cerebral cortical potentials can be evoked by stance perturbation, and there is speculation that they represent the activation of supraspinal centers in preparation for the control and coordination of motor movements that maintain balance. We sought to determine if these potentials differed in old people at risk of falls. METHODS: Cortical potentials were generated by the sudden forward translation of a weight-bearing platform in 8 healthy young subjects and in 33 old subjects stratified by their functional capacity. Dependent measures were compared with non-parametric tests of significance. RESULTS: Perturbing the stance of young subjects produced a biphasic scalp potential centered at the vertex with an early positive peak at 60 ms and a larger, 45 microV, negative peak at 123 ms. In old subjects the response was delayed and the vertex-negative component was smaller and bifid. The interval between the two components of the negative peak was prolonged in a subgroup of old subjects with reduced mobility. CONCLUSIONS: Delays in sensory conduction may play a role in subsequent maladaptive motor responses to stance perturbation that can result in falls and injury in old people.

Adult↗

PubMed1996

Balance and strength training in older adults: intervention gains and Tai Chi maintenance.

OBJECTIVE: To determine the effect on balance and strength of 3 months of intensive balance and/or weight training followed by 6 months of low intensity Tai Chi training for maintenance of gains. DESIGN: Randomized control intervention. Four groups in 2 x 2 design: Control, Balance, Strength, Balance + Strength, using blinded testers. SETTING: Exercise and balance laboratory at University of Connecticut Health Center. PARTICIPANTS: Subjects were 110 healthy community dwellers (mean age 80) who were free of dementia, neurological disease, and serious cardiovascular or musculoskeletal conditions. INTERVENTIONS: Short-term training (3 months) occurred 3 times/week (45 minutes Balance and Strength, 90 minutes Balance + Strength). Balance training included equilibrium control exercises of firm and foam surfaces and center-of-pressure biofeedback. Strengthening consisted of lower extremity weight-lifting. All subjects than received long-term group Tai Chi instruction (6 months, 1 hour, 1 time/week). MEASUREMENTS: Losses of balance during Sensory Organization Testing (LOB), single stance time (SST), voluntary limits of stability (FBOS), summed isokinetic torque of eight lower extremity movements (ISOK), and usual gait velocity (GVU). RESULTS AND CONCLUSIONS: Balance training meaningfully improved all balance measures by restoring performance to a level analogous to an individual 3 to 10 years younger: LOB = -2.0 +/- 0.3 (adjusted paired differences, P < .005 ANOVA); SST = 7.0 +/- 1.2 sec; and FBOS = 9.0 +/- 2.0% of foot length (P < .05). Strengthening increased ISOK by 1.1 +/- 0.1 Nm kg-1 (P < .005). There was no interaction between balance and strength training. Significant gains persisted after 6 months of Tai Chi, although there was some decrement.

Aged↗

PubMed1995

Dynamic balance in older persons: effects of reduced visual and proprioceptive input.

BACKGROUND: Understanding the motor and sensory contributions to balance function in older persons is important in order to design effective interventions to prevent falls and loss of mobility. We tested the contributions of visual and proprioceptive input, muscle strength, and age to balance performance in 110 subjects free of clinical evidence of neurologic disease (mean age 80 years). METHODS: The EquiTest Sensory Organization Test was used to present sequential conditions that altered sensory input in a 2 (tactile/proprioceptive input) x 3 (visual input) design. Center of force and shear force data were recorded from the platform; the primary outcomes were loss of balance (LOB) and anterior-posterior center of force (COF) displacement as a proportion of foot length (COFD). RESULTS: Subjects had 3.5 +/- 2.7 LOB during testing. Reduction of vision input increased the odds ratio of a LOB 5.7 fold (3.9, 8.4, 95% CI) in unstable surface conditions, but adaptation with repeated trials was substantial. The adjusted odds ratio of a LOB was 0.65 and 0.45 in the second and third trials, respectively, compared to the first. Muscle strength and age were independent predictors of LOB. Gait velocity, single stance balance, and reported difficulty with ambulation, mobility, and instrumental activities of daily living were also associated with LOB. CONCLUSIONS: Performance on clinical tests of strength, balance, and gait was associated with performance on a challenging balance test which reduced sensory input and effectiveness of motor responses. Adaptation to challenging balance conditions was substantial in this group of older subjects, but was diminished in the oldest subjects.

Activities of Daily Living↗

PubMed1995

Strength is a major factor in balance, gait, and the occurrence of falls.

We studied the effects of lower extremity strength as well as gait and balance on the occurrence of falls in nursing home residents. Nursing home residents with a history of falls had less than half of the knee and ankle strength of nonfalling subjects residing in the same home. The differences were more prominent at the ankle than the knee, and were most pronounced in the ankle dorsiflexors, where they were one-tenth that of controls. Also of note was the fact that this same group of fallers had slowed gait velocity (58% of control) as well as an impaired response to postural perturbation as determined on the Postural Stress Test (55% of control). In a recently completed study we measured strength as balance (EquiTest balance platform) of community-dwelling subjects. The occurrence of loss of balance during the sensory organization test was correlated with diminished lower extremity (Pearson R = -.36, p = .001) as well as ankle dorsi and plantar flexion moments (Pearson R = -.37, p = .001). Using a logistic regression model, we demonstrated an independent effect of strength on the odds ratio of an SOT-LOB; for each newtonmeter per kg increase in strength there was a 20% decrease (95% CI, .74-87) in the odds ratio. The data from both nursing home and community-dwelling subjects indicate a strong relationship of lower extremity strength to balance and gait. The nursing home studies demonstrated an association between these functions and the occurrence of falls.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidental Falls↗

PubMed1994

Clinical application of the forearm tourniquet.

We undertook this prospective study of 148 consecutive hand and wrist procedures to evaluate the safety and efficacy of the forearm tourniquet. Patients were assigned to three groups based on tourniquet pressure used, ranging from 50 to 125 mmHg above systolic blood pressure. The forearm tourniquet was well tolerated by all patients. No patient had neurologic complications. Minimal intraoperative bleeding occurred when the pressure was greater than 75 mmHg above systolic blood pressure. The forearm tourniquet is a safe and effective means of providing a bloodless field for wrist and hand surgery.

Forearm↗

PubMed1994

Gender differences in the balance of healthy elderly as demonstrated by dynamic posturography.

BACKGROUND: Prior studies indicate that older women fall more often than men although there is no evidence of gender-based balance differences. Using a force platform, we measured the effects of restricted sensory input and support surface movement to detect gender differences in balance. METHODS: Healthy, elderly community dwellers (N = 234, mean age = 76 +/- 5 years, 52% female) were administered the following perturbations on the balance platform: The platform and/or visual surround were fixed or tilted proportionally to the subject's sway with the eyes open or closed, forward or backward horizontal translations, and toes-up and toes-down rotations. RESULTS: Gender-based balance differences were not present during quiet standing, or when the support surface or visual input were manipulated separately. Women swayed and lost their balance more than men when the surface was sway-referenced while vision was compromised, but by the third trial their sway control was comparable to the men. Women also initially lost their balance more frequently than men during toes-up and -down rotations, and compared to men continued to lose their balance more often during repeated toes-up rotations. Finally, women developed less angular momentum than men in response to forward platform rotations. DISCUSSION: Elderly women show impairments of balance when simultaneously deprived of visual and somatosensory inputs or during a backwards destabilization. Since there is little evidence for a CNS source for such gender differences, biomechanical origins (e.g., dorsiflexion strength and range of motion) are a more likely cause. Limited postural control of women under conditions stressing balance may explain their greater frequency of falling.

Adaptation, Physiological↗

PubMed1994

Ejection of the proximal scaphoid in a trans-scaphoid perilunate fracture dislocation. A case report.

Trans-scaphoid perilunate fracture dislocations are difficult injuries to treat. Described herein is the unusual case of a trans-scaphoid perilunate fracture dislocation in which the proximal scaphoid fragment was ejected into the volar aspect of the distal forearm. The significant displacement of the proximal fragment represented complete devascularization of this piece. This unique fracture raised difficult management issues in the treatment of this injury. A primary proximal row carpectomy was performed, with a successful clinical result.

Adult↗

PubMed1993

Altered sensory function and balance in older persons.

The effects of three different visual inputs (eyes open, eyes closed, and inaccurate) while standing on an unstable surface (respectively, UEO, UEC, UI) were compared in a group of healthy elderly community dwellers (N = 239; mean age 76) and young (N = 34; mean age 34) adults. Subjects with medical factors known to affect balance were excluded. Body sway and loss of balance measured dynamic force platform (EquiTest, NeuroCom International). Visual and somatosensory inputs were rendered inaccurate through tilting of the standing surface and/or the visual surround proportional to the subject's angle of sway (sway-referencing). The elderly group had significantly more difficulty balancing during UEC and UI, and a larger proportion lost their balance during UI. These findings are compared to those of other dynamic posturography studies in which sensory inputs were controlled. Issues of age, frailty, screening, and test protocol are addressed in order to account for differences in results among studies.

Aged↗

PubMed1993

Training balance and strength in the elderly to improve function.

Short-term exposure to altered sensory input or destabilizing platform movement results in significant improvement in sway control and inhibition of inappropriate motor responses, resulting in improved balance during repetitive testing. In addition, there is recent evidence that strength and function can be increased in both active and frail elderly who participate in strength training programs. Therefore, the hypotheses to be tested are that (1) balance training alone, or (2) strength training alone will each be capable of significantly improving balance, gait, and functional mobility, and that (3) a combined program of balance and strength training will be more effective than either approach alone. These hypotheses will be tested relative to a control group, using a 2 x 2 design (30 subjects per group), in a community-dwelling elderly at least 75 years of age. Intervention sessions of at least 45 minutes will occur three times per week for 3 months, with 6 months of follow-up, home-based Tai Chi training. The primary outcome variable is a basic measure of functional balance, ie, the occurrence of loss of balance during tilts of the support and/or movement of the visual surround.

Aged↗

PubMed1992

A dynamic posturography study of balance in healthy elderly.

Using dynamic posturography, we studied the balance of 234 community-dwelling elderly subjects (mean age, 76 +/- 5 years) as well as 34 young controls (mean age, 34 +/- 12 years). Almost all measures of balance were worse in elderly subjects compared with young controls. The decrements in older persons indicate a diminished capacity to process conflicting sensory input as well as a possible narrowing of the limit of stability (or, alternatively, an increase in sway). We propose that this occurs most likely as a result of biomechanical or central processing changes as opposed to diminished sensory or vestibular input. Furthermore, with difficult tasks sequentially presented, the performance of the older subjects improved, suggesting that balance, at least in the short term, adapts to stressful conditions. In these elderly subjects screened for age-related diseases affecting balance, only small decrements of balance occurred between the ages of 70 and 85 years. This nominal decrease over a 15-year span suggests that clinically significant balance impairment is the result of age-related disease rather than an inevitable consequence of aging and is therefore potentially treatable.

Adult↗

PubMed1990

Gait assessment in the elderly: a gait abnormality rating scale and its relation to falls.

We evaluated the gait of 49 nursing home residents (27 of whom had a history of recent falls), and 22 controls. Measures consisted of stride length and walking speed, as well as a videotape-based analysis of 16 facets of gait. The study demonstrates that stride length, walking speed, and the assessment of videotaped gait correlated well with each other and were significantly impaired in fallers compared to controls. Arm swing amplitude, upper-lower extremity synchrony, and guardedness of gait were most impaired in fallers. Although subjects who fell were more often demented than controls, it is likely that this represents a selection bias in nursing homes. Visual rating of gait features in the nursing home population is a simple and useful alternative to established methods of gait analysis.

Accidental Falls↗

PubMed1989

Brain white-matter changes in the elderly prone to falling.

Falls and impaired gait are a major source of morbidity in the elderly. Why some elderly become prone to falling is often unclear. We analyzed the gait, equilibrium, and brain computed tomography results of 40 elderly subjects without evidence of neurologic disease known to be associated with falls. Twenty of these subjects were prone to falling and the remaining 20 were nonfalling controls. These two groups were comparable in terms of age and sex (mean age, 83.3 years [SE, 1.7 years]). The group of fallers had significantly worse gait and equilibrium scores and a greater degree of white-matter hypodensity on computed tomography. White-matter hypodensity correlated with impaired gait and equilibrium scores but not with impaired performance on cognitive testing. This study reveals the association of white-matter disease with gait and balance impairment leading to falls in the elderly.

Accidental Falls↗

PubMed1986

Stressing the postural response. A quantitative method for testing balance.

Using a series of graded destabilizing forces, we have developed a simple quantitative test of the postural response: the Postural Stress Test (PST). Suitable for widespread testing of elderly subjects, the test evaluates the subject's ability to avoid a fall as well as the appropriateness of the response. We have determined that by comparison with young subjects, the elderly controls have compromised although functionally effective balance. On the other hand, the balance response was severely compromised in half of the individuals with a history of falls. Experience with the Postural Stress Test suggests it will predict those elderly individuals with a tendency to fall as well as provide a simple mechanism for studying the balance response in the elderly.

Accidental Falls↗

PubMed1985

Gait and balance in the elderly. Two functional capacities that link sensory and motor ability to falls.

Neuromuscular function, which underlies efficient gait and balance, deteriorates with age and disease. A review of the literature and of data from the current study suggests the presence of poor gait and balance in elderly individuals who have a history of multiple falls. The tests of gait and balance are simple to perform and therefore may be widely applicable in evaluating individuals at risk of falls. Quantitative studies of motor and sensory function, vibratory sensation, and electrophysiologic studies of nerve integrity are discussed. Deteriorating motor and sensory control mechanisms appear to play an important role in falling.

Accidents↗

PubMed1979

The echocardiographic association of mitral valve prolapse and mitral anulus calcification.

Mitral anulus calcification (MAC) and mitral valve prolapse (MVP) are frequently diagnosed conditions. We studied two patients with mild or moderate mitral regurgitation who demonstrated both MAC and MVP on angiography and echocardiography. M-mode echocardiography is probably the definitive test for confirming the presence of MVP. Echocardiography is moderately sensitive in the diagnosis of cardiac calcification, such as MAC, but M-mode echocardiography may not detect the MAC in the majority of patients with both MVP and MAC demonstrated by angiography.

Calcinosis↗