Models for actin filament organization in the erythrocyte membrane skeleton.
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Biomedical subjects
Publications and source records attributed to V Fowler.
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The implementation of the Care Programme Approach (CPA) in English mental health services has been slow to proceed despite general support, both in England and in other countries, of its principles of good practice. This study set out to evaluate the implementation of the CPA directly from patients' experience using the "Your Treatment and Care" assessment tool. The results of a survey of 503 patients across five NHS Trusts in England showed that many patients did not have a copy of their care plan and had not been involved in the care planning procedure. Many reported shortcomings in their experience of their key worker and their psychiatrist. However, there was substantial variation in experience across services. "Your Treatment and Care" showed good internal reliability, was acceptable to users, and appeared to be able to access actual experiences better than a traditional "satisfaction" item. It appears to be very useful as a benchmarking tool and is now being used in services across the UK, the USA and Australia.
This paper reports the development, construction and use of a new system for the measurement of linear kinematics in one, two or three dimensions. The system uses a series of rotary shaft encoders and inelastic tensioned strings to measure the linear displacement of key anatomical points in space. The system is simple, inexpensive, portable, accurate and flexible. It is therefore suitable for inclusion in a variety of motion analysis studies. Details of the construction, calibration and interfacing of the device to an IBM PC computer are given as is a full mathematical description of the appropriate measurement theory for one, two and three dimensions. Examples of the results obtained from the device during gait, running, rising to stand, sitting down and pointing with the upper limb are given. Finally it is proposed that, provided the constraints of the system are considered, this method has the potential to measure a variety of functional human movements simply and inexpensively and may therefore be a valuable addition to the methods available to the motion scientist.
OBJECTIVE: An investigation of the effect of the length of knee extensor muscles on the pendulum test. DESIGN: Descriptive. Statistical analysis utilized analysis of variance with planned comparisons. SETTING: Community clubs and a stroke rehabilitation unit. PARTICIPANTS: Twenty subjects aged 54 to 83 yrs, more than 6 weeks after stroke, and 31 healthy subjects aged 60 to 79 yrs. OUTCOME MEASURES: Two tests: pendulum test and knee extensor muscle length test. RESULTS: For both affected and intact legs, stroke subjects had significantly smaller angle of reversal (p < .001), peak angular velocity (p < .001), and maximum passive knee flexion (p < .001) than healthy subjects. When angle of reversal was normalized for passive knee flexion, there were no significant differences between healthy and stroke subjects. There were no significant differences in any variable between the intact and affected legs of the stroke subjects. CONCLUSION: Soft tissue changes, rather than hyperreflexia, may explain the decreased angle of reversal and peak angular velocity in the stroke subjects studied.
OBJECTIVE: To investigate changes in postural sway while standing, walking parameters, and performance of functional tasks during rehabilitation in a group of traumatic brain injury (TBI) patients. DESIGN: Descriptive. SETTING: Inpatient brain injury rehabilitation unit. PARTICIPANTS: Thirteen subjects undergoing rehabilitation after severe TBI. OUTCOME MEASURES: Two assessments were performed, 2 to 6 weeks apart that included the following: postural sway in three stance conditions; temporal and spatial parameters of walking; functional assessments of walking, standing up, reaching while standing, and stair climbing. RESULTS: There were significant reductions in postural sway in all stance conditions (p < .05) and significant increases in velocity of walking (p < .05), stride length (p < .01), and left and right step lengths (p < .01). Performance on all functional tasks improved (p < .05) except for functional reach. There were no significant correlations between changes in postural sway and changes in walking parameters or functional assessments. CONCLUSION: This study demonstrated significant improvements in postural sway, walking parameters, and functional tasks during a relatively short period of rehabilitation after severe TBI. Improvements in standing balance appear to be independent of improvements in walking performance, suggesting that different mechanisms underlie improved control of these tasks.
BACKGROUND: Acute renal failure has long been associated with severe Rocky Mountain spotted fever (RMSF). Despite many descriptions of the protean manifestations of this disease, relatively little is known concerning the risk factors for acute renal failure. Only a few studies have examined the outcome of patients infected with Rickettsia rickettsii who develop renal insufficiency, and these studies had methodological problems. OBJECTIVE: To study the incidence, risk factors, and outcomes of acute renal failure in a large group of hospitalized patients with definite or probable RMSF. METHODS: The clinical records of 114 patients with definite or probable RMSF were retrospectively reviewed to identify clinical and biochemical abnormalities at the time of admission that were associated with the development of acute renal failure and subsequent mortality. Renal failure was defined as a serum creatinine (Cr) above 2 mg/dL. Logistic regression was used to study the association between these variables and the outcomes during hospitalization: death and the development of acute renal failure. RESULTS: The mortality rate in this series was 14%; 19% of the patients developed acute renal failure. The development of acute renal failure increased the odds ratio (OR) of dying by a factor of 17 (P = 0.001). Factors at the time of hospitalization that were associated at a univariate level with subsequent mortality included elevated serum Cr, increased age, increased level of AST, increased level of bilirubin, decreased serum sodium and platelet count, the presence of neurological involvement, and being male. Both the presence of neurological involvement and an elevated serum Cr at presentation were independently associated with increased mortality by multivariate analysis. Three patients developed acute renal failure that required hemodialysis, and only 1 of these 3 patients survived; he was ultimately discharged with a normal serum Cr. Factors at presentation that were associated with the development of acute renal failure included increased bilirubin, increasing age, thrombocytopenia, and the presence of neurological involvement. Both age and decreased platelet count at presentation were independently associated with the development of acute renal failure by multivariate analysis. CONCLUSION: Acute renal failure was a frequent complication of RMSF in this series of patients from a tertiary referral medical center. The presence of acute renal failure was strongly associated with death. Clinical and biochemical variables are useful in predicting which patients will develop acute renal failure.
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Tumor-associated antigens (TAA) can be detected in the urine of sarcoma patients by a variety of assays. This study was designed to correlate antigen activity in three assays: complement fixation assay (CFA), enzyme-linked immunosorbent assay (ELISA), and Western blot (WB). This study identifies the antibody class responsible for TAA identification in these assays and characterizes the nature of the antigen. One hundred eighty-nine urine samples from eight sarcoma patients with known levels of TAA in CFA were tested in ELISA and WB. Allogeneic anti-TAA containing sera (1 degree antibody) from a sarcoma patient was reacted with urine samples followed by detection with alkaline phosphatase-linked goat anti-human IgG and IgM (2 degree antibody in both assays). Reactivity in CFA correlated to IgM reactivity in ELISA and WB (chi 2 test, P less than 0.001). No correlation was found to IgG reactivity in either assay. Reactivity in WB vs ELISA was also highly correlated for IgM (P less than 0.001). TAA was visualized in WB as a distinct pattern of repeating bands, with most bands being detected in the range 30,000-60,000 Da. The separation between bands approximated 2500-3000 Da, suggesting a molecule composed of repeating subunits. This study suggests that the antigen is glycoprotein in nature, and that the detecting antibody is of the IgM class.
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A low-salt extract prepared from human erythrocyte membranes forms a solid gel when purified rabbit muscle G- or F-actin is added to it to give a concentration of approximately 1 mg/ml. This extract contains spectrin, actin, band 4.1, band 4.9, hemoglobin, and several minor components. Pellets obtained by centrifugation of the gelled material at 43,000 g for 10 min contain spectrin, actin, band 4.1, and band 4.9. Although extracts that are diluted severalfold do not gel when actin is added to them, the viscosity of the mixtures increases dramatically over that of G-actin alone, extract alone, or F-actin alone at equivalent concentrations. Heat-denatured extract is completely inactive. Under conditions of physiological ionic strength and pH, information of this supramolecular structure is inhibited by raising the free calcium ion concentration to micromolar levels. Low-salt extracts prepared by initial extraction at 37 degrees C (and stored at 0 degree C) gel after actin is added to them only when warmed, whereas extracts prepared by extraction at 0 degree C are active on ice as well as after warming. Preincubation of the 37 degrees C low-salt extract under conditions that favor conversion of spectrin dimer to tetramer greatly enhances gelation activity at 0 degree C. Conversely, preincubation of the 0 degree C low-salt extract under conditions that favor conversion of spectrin tetramer to dimer greatly diminishes gelation activity at 0 degree C. Spectrin dimers or tetramers are purified from the 37 dgrees or 0 degree C low-salt extract by gel filtration at 4 degrees C over Sepharose 4B. The addition of actin to either purified spectrin dimer (at 32 degrees C) or tetramer (at 0 degree C or 32 degrees C) results in relatively small increases in viscosity, whereas the addition of actin to a high-molecular-weight complex (HMW complex) containing spectrin, actin, band 4.1, and band 4.9 results in dramatic, calcium-sensitive increases in viscosity. These viscosities are comparable to those obtained with the 37 degrees or 0 degree C low-salt extracts. The addition of purified band 4.1 to either purified spectrin dimer (at 32 degrees C) or purified spectrin tetramer (at 0 degree C) plus actin results in large increases in viscosity similar to those observed for the HMW complex and the crude extract, which is in agreement with a recent report by E. Ungewickell, P. M. Bennett, R. Calvert, V. Ohanian, and W. B. Gratzer. 1979 Nature (Lond.) 280:811-814. We suggest that this spectrin-actin-band 4.1 gel represents a major structural component of the erythrocyte cytoskeleton.
Fluorescein isothiocyanate-labelled integral membrane proteins are mobile in the membranes of human erythrocytes that have fused (and haemolysed) by Sendai virus or polyethylene glycol. Minimum diffusion coefficients are of the order of 10(-11) cm2 s-1 at 37 degrees C. This mobility is reduced several-fold at room temperature, not detected at 0 degrees C, and is significantly greater in fresh than in aged blood. Mobility was assessed by observing the spread of fluorescence on labelled cells which had been fused with unlabelled cells; neither intramembrane particle aggregation nor spectrin release occurred during this process.