Biomedical subjects
Publications and source records attributed to M Magnusson.
The purpose of this study was to determine if the overall body height, as measured by a stadiometer, could be increased by brief episodes of hyperextension rather like a stretch that people frequently employ when arising. The subjects were loaded with 10 kg and the recovery with quiet sitting was compared to hyperextension 'stretches'. It was found that 15 s of hyperextension caused a significant temporary height increase.
The effect of the protein kinase C (PKC) inhibitor chelerytrine (Ch) and the PKC activator 12-0-tetradecanoyl-phorbol-13-acetate (TPA) on the cytosolic calcium concentration ([Ca2+]i) in isolated intact rabbit afferent arterioles was investigated. [Ca2+]i was measured in the proximal and distal parts of the arteriole. Administration of 1 microM Ch gave rise to a peak followed by an elevated level of [Ca2+]i in both these parts. Neither the peak nor the elevated level of [Ca2+]i was significantly reduced by 1 microM nifedipine. The relative peak increase in [Ca2+]i in response to 1 microM noradrenaline (NA) or to 10 nM angiotensin II (AII) was significantly blunted in both parts after preincubation with 1 microM Ch. Depolarization with 25 mM K+ increased [Ca2+]i in both parts. Preincubation with Ch did not affect the increase in [Ca2+]i induced by 25 mM K+. TPA (10 and 100 nM) did not significantly affect the basal [Ca2+]i in the afferent arteriole. The [Ca2+]i response to NA or 25 mM K+ was not affected by TPA. We conclude that blockade of PKC increases [Ca2+]i in afferent arteriolar smooth muscle by a mechanism independent of L-type voltage-sensitive calcium channels. Inhibition of PKC blunts the relative increase in [Ca2+]i in response to AII and, to a lesser extent, that induced by NA. We conclude that PKC might be important in modulating the calcium changes that occur in response to these vasoconstrictors.
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This study compared the differences in energy efficiency (energy cost) in children with myelomeningocele ambulating with either reciprocating gait orthoses (RGOs) or hip-knee-ankle-foot orthoses (HKAFOs). There were 15 children who ambulated with RGOs and 11 children braced and ambulating in HKAFOs. Velocity was measured in m/s, energy consumption was measured in mL/kg/min, and energy cost (energy consumption/velocity) was measured in mL/kg/m. Children in HKAFOs had a significantly higher energy consumption rate than children in RGOs. However, children who swing through in a HKAFO have a significantly faster velocity than children who ambulate with the RGO using a reciprocating pattern. The increased energy cost in the RGO group is influenced by their slower velocity, just as the decreased energy cost in the HKAFO group is influenced by their increased velocity. Therefore it appears that children in HKAFOs are more energy efficient than children in RGOs.
The aim of the present study was to evaluate the rationality of health check-ups by a physician of 18-month-old children. The study population consisted of all 4075 children in Uppsala county who were 18 months old in 1994 and should have had a routine health examination at that point. Information about the 18-month health examination came from primary data in a longitudinal child health register regarding all children of preschool age. The children in the study population were classified into two main categories, namely children with no newly detected health problem (92.6%) and children in whom a new health problem was detected (3.3%). Data from the register and other sources were analysed to categorize the health problems by severity and type and to determine who (parents, nurse or physician) had identified each. Among the 4075 children in the study population, 135 children were identified as having a newly detected health problem. One-third of them were actually healthy (false positive). Among the 92 verified new health problems (2.3%), 48 were minor, 42 were moderate and 2 were severe. More than half of the moderate health problems were transient infections. The main conclusion of the study is that, under current conditions in Sweden, it would be reasonable to replace the 18-month examination by a physician with an examination by a nurse, this examination being particularly orientated towards developmental and psychosocial problems.
Three commercially available enzyme-linked immunosorbent assays (ELISAs) from Gull, Biotest, and Behring (Enzygnost) and two latex agglutination tests for heterophile antibodies (Monolatex [Biotest] and Mono-Lex [Trinity Laboratories]) were evaluated for the diagnosis of primary Epstein-Barr virus (EBV) infection and EBV seropositivity. Two hundred fourteen consecutive samples from 197 patients with symptoms of primary EBV infection were analyzed by the five assays at a clinical microbiology laboratory. The samples were also analyzed independently by immunofluorescence methods at a reference laboratory. According to the reference methods, 37 patients (40 serum samples) had primary EBV infections, 120 patients (127 serum samples) had had past EBV infections, 33 patients (36 serum samples) were seronegative, and 7 patients (11 serum samples) exhibited atypical reactions. The respective sensitivities and specificities for the diagnosis of primary EBV infection were 95 and 100% for the Gull assays, 100 and 94% for the Biotest assays, and 100 and 89%, for the Enzygnost assays. The Monolatex and Mono-Lex methods showed similar sensitivities and specificities (78 to 85% and 100 to 99%, respectively) for the diagnosis of primary EBV infection. This study demonstrates the usefulness of commercially available assays for the rapid diagnosis of primary EBV infection, but also the importance of large-scale testing of routine samples before choosing an assay.
To assess changes in postural control among healthy elderly and to correlate with suspected age-related events, 33 women and 16 men were studied. Postural control was evaluated by vibration-induced body sway, measured on a force platform, and vibration sensation was tested with a tuning fork. Occurrence of spontaneous gaze and head-shake-induced nystagmus was observed with infrared charged couple device (CCD) cameras and the subjects' medical history was reviewed. Vibration perception was the major determinant for the magnitude of body sway. Although these senior citizens considered themselves healthy, they had a variety of ailments in their medical history, diminished vibration sensation and a high prevalence of vestibular asymmetry. Age per se was not a determinant factor in any of the findings. The study suggests that interest should also be directed to the status of sensation in the legs and vestibular asymmetry when assessing balance function in the elderly. Furthermore, the term "age concomitant" may be more appropriate than "age dependent" when describing decrements of functions such as postural control in elderly subjects.
Back supports, or lifting belts, are widely used. Subjects, free of low back pain, lifted in a simulated task, meeting the 1993 NIOSH guidelines. The back support reduced the electromyographic signal in the dorsal muscles. The back support also reduced the height loss as measured by a stadiometer. In most subjects the support also gave a subjective impression of increased support and increased lifting capacity.
OBJECTIVE: To automatize the lumbar physical examination with an acceptable rate of error. DESIGN: An external skin marker method for automatizing the physical examination was developed and its ability to discriminate between normal and abnormal subjects tested in a blind clinical trial. BACKGROUND: The low reproducibility of clinical findings, even among experienced doctors, has been well documented. This is of particular concern and may explain why there is such a wide variation in surgical rates across the USA (tenfold for disc herniation). Inconsistencies among physicians in the evaluation of benign low back conditions make standardization desirable. METHODS: A computerized physical examination was used to evaluate patients with low back pain and compare their results with a normative database obtained from a selection of healthy subjects. A high-resolution motion analysis system tracked the movement of skin markers placed on the midline and pelvis. Surface EMG electrodes placed above L(5) collected data from multifidus. From the kinematics of skin markers during flexion--extension with lifts up to 32 kg, and lateral bending with lifts up to 10 kg, the following parameters were estimated: lumbosacral angle and elongation, contribution of each lumbar segment to the lordosis reduction, relative pelvic/spine motion, and trunk velocity. First the average normal value for each estimated parameter was determined using 40 normal subjects. For each subject the difference between his parameter and the normal was processed by an expert system generating a normality index varying from zero (perfect abnormal) to one (perfect normal). To develop the expert system's rules, a preliminary group of 20 very abnormal subjects was used, such that the normality index separated them from the normals. For validation, a set of 29 back-sprain patients and another set of 42 discogram-positive patients were selected. Each subject was tested and his computerized normality index calculated without any clinician's input, then compared with the clinician's evaluation, which was taken to be the gold standard. The receiver operating characteristic technique was used to quantify the discrepancies. RESULTS: The expert system could detect clinically abnormal subjects with accuracy (sensitivity 83-91% and specificity > 90%) whele providing quantitative information on workers' functional capacities. CONCLUSIONS: Once a reference normative database is agreed upon, each patient can be compared with that reference according to the same rules, with the resulting machine classification being independent of the clinician. This eliminates the inter- and intra-clinician variability in patient follow-up. Because of the severity of the selection criteria, this study is based upon a relatively restricted number of subjects, as well as a limited normative database of 40 subjects. RELEVANCE: It is possible to automate the lumbar physical examination with an acceptable error rate. This technique permits the objective consistent assessment of lumbar function, and thus allows the comparison of different treatment regimes for lumbar dysfunction.
OBJECTIVE: To assess postural performance in patients with dizziness of suspected cervical origin in whom extracervical causes had been excluded, and to assess the effects of physiotherapy on postural performance and subjective complaints of neck pain and dizziness. DESIGN: Prospective, randomized, controlled trial. SETTING: Primary care centers and a tertiary referral center. PATIENTS AND SUBJECTS: Of 65 referrals, 43 patients were excluded because extracervical etiology was suspected. Of the remaining 22 patients, 17 completed the study (15 women, 2 men, x age 37 yr, range 26-49). The controls were 17 healthy subjects (15 women, 2 men, x age 36 yr, range 25-55). INTERVENTION: Physiotherapy based on analysis of symptoms and findings, and aimed to reduce cervical discomfort. Patients were randomized either to receive immediate physiotherapy (n = 9), or to wait 2 months, undergo repeat measurements, and then receive physiotherapy (n = 8). MAIN OUTCOME MEASURES: Posturography, measuring velocity and variance of vibration-induced body sway and variance of galvanically induced body sway. Subjective intensity of neck pain (Visual Analog Scale ratings, 0-100), intensity and frequency of dizziness (subjective score 0-4). RESULTS: The patients manifested significantly poorer postural performance than did healthy subjects (.05 > p > .0001). Physiotherapy significantly reduced neck pain and intensity and the frequency of dizziness (p < .01), and significantly improved postural performance (.05 > p > .0007). CONCLUSIONS: Patients with dizziness of suspected cervical origin are characterized by impaired postural performance. Physiotherapy reduces neck pain and dizziness and improves postural performance. Neck disorders should be considered when assessing patients complaining of dizziness, but alternative diagnoses are common.
The risk of experiencing low back pain is associated with mechanical factors. Anatomic factors, such as advancing pregnancy, can also place extra mechanical stress on the lower back. Mechanical factors, such as those related to the workplace, can be minimized by ergonomic interventions. A constrained, seated posture, in combination with exposure to whole-body, jolt/vibration can impose significant stresses on the posterior intervertebral disc and can lead to back muscle fatigue. Interventions that reduce the jolt/vibration magnitude and duration of exposure will decrease the mechanical work performed on the intervertebral disc. Such interventions range from jolt/vibration isolating seats and vehicle cabs, to decreasing exposure time and maintaining simple supported postures during ingress and egress. Improvements in seat configuration can reduce the intervertebral disc pressure and the strain on the posterior disc.
We sought to determine if patients with cystic fibrosis and sputum cultures positive for Mycobacterium avium complex (MAC) have delayed-type hypersensitivity to an M. avium sensitin. Seventeen (33%) of 51 selected patients had MAC isolated from at least one sputum culture. Skin tests with purified protein derivative and M. avium sensitin demonstrated that five (10%) of 51 patients were anergic, and anergy was correlated with use of systemic steroids. Sixteen (35%) of 46 nonanergic patients had M. avium-dominant skin test reactions. Twelve (75%) of these 16 patients with cultures positive for MAC had M. avium-dominant skin tests; the specificity of skin testing was 87%. These data suggest that most patients with cystic fibrosis and sputum cultures positive for MAC have infection rather than colonization with MAC. Skin testing with M. avium sensitin is a sensitive and specific method for screening these infections.
BACKGROUND: Continuous epidural infusions of local anaesthetics have become increasingly popular in postoperative pain treatment, especially as they permit early mobilisation. Ropivacaine is a promising new agent which induces more pronounced sensory than motor blockade. This study was focused on the influence of continuous epidural infusion of ropivacaine on impulse conduction in large nerves (by measurement of F and H latencies), and on the subjects' ability to maintain postural control during mobilisation. METHODS: Healthy male volunteers received 0.1%, 0.2% or 0.3% ropivacaine, and bupivacaine 0.25% was used as reference. A bolus epidural injection of 10 ml of the drug, at L2/3 level, was followed by continuous infusion at 10 ml/h for 21 h. Motor blockade was assessed by mechanical measurements of force during big toe flexion and by recording of F latency. Sensory blockade was monitored by pin-prick and Thermotest methods, and by H latency recording. The subjects' ability to perform a postural test was evaluated by posturography. RESULTS: The F and H latencies became prolonged/abolished dose-dependently. With ropivacaine, F latency recovered significantly later than motor function (P = 0.0002), and H latency recovered later than normal pin-prick perception (P = 0.0006). However, the duration of partial blockade of thermoperception was comparable to that of H latency prolongation. Posturographically, the subjects receiving 0.1% ropivacaine differed significantly from all others (P < 0.001) in that they were able to maintain postural control during the infusion. The recovery period after termination of infusion was significantly shorter with ropivacaine than with bupivacaine for all measured variables. CONCLUSION: Recovery of postural control with 0.2% and 0.3% ropivacaine is significantly faster than with bupivacaine 0.25%. H latency recording allows detection of epidural blockade intensity that does not prevent subjects from performing postural tests.
OBJECTIVE: The aim was to evaluate the effectiveness of an early screening programme for communicative disturbances in relation to the health status of the child at the age of 4 years. MATERIALS AND METHODS: A case-control study including 705 cases and 2451 controls was performed. RESULTS: Cases with communication disorders as well as other types of disabilities at 4 years of age showed a higher frequency of deviant screening results on each screening occasion. The sensitivity for the screening programme amounted to 24.8%, the specificity was 95.5% and the positive predictive value was 61.2%.
Asymmetric vestibular function affects optokinetic after-nystagmus (OKAN) in man, but little is known about the involvement of cervical proprioception in the visual-vestibular interaction reflected as OKAN. We studied the effect of asymmetric cervical proprioception induced by active maximal, or passive 70 degrees sustained horizontal head rotations on OKAN in 16 healthy subjects. We evoked optokinetic nystagmus (OKN) by means of a whole-field optokinetic drum rotated at a velocity of 90 degrees/s for 60 s. Following left- and right-beating OKN, we recorded OKAN in complete darkness for 60 s by DC electro-oculography. Both passively and actively sustained head rotations significantly reduced the intensity of OKAN beating in the direction opposite to the head rotation, while OKAN beating in the direction of the head rotation remained unchanged. This resulted in significant asymmetry between OKAN beating in the direction of the head rotation vs. that in the opposite direction. The findings show that in normal subjects neck proprioception converges with visual and vestibular signals and affects subcortical OKN. Asymmetric neck proprioception from neck disorders may be hypothesized to induce dizziness or vertigo in situations where OKN is evoked.
Patients under going orthopedic surgery are at high risk of developing deep vein thrombosis. One hundred and thirty-eight consecutive patients undergoing total hip replacement or hip fracture surgery were included in this study. They were surveilled with colour Doppler ultrasound (CDU) and bilateral ascending contrast phlebography. The prevalence of proximal and distal DVT in this study was 5.8% and 20.3% respectively. CDU has a satisfactory sensitivity in patients with symptomatic deep vein thrombosis, especially in the proximal region. These results could not be confirmed in the present study of asymptomatic patients. The sensitivity was 62.5% (95% confidence interval: C.I. 24-91%) and the specificity 99.6% (C.I. 98-100%) for proximal DVT; 53.6% (C.I. 34-73%) and 98% (C.I. 96-99%) respectively for distal thrombi. the overall sensitivity was 58.1% (C.I. 39-75%) and the specificity 98% (C.I. 96-99%). The positive predictive value was 83.3% (C.I. 36-99%) and 75% (C.I. 51-91%) for proximal and distal DVT respectively. The negative predictive value was 98.9% (C.I. 98-100%) and 94.9% (C.I. 92-98%) for proximal and distal DVT respectively. The results of this study showed that even with a highly specialised and experienced investigator the sensitivity of CDU was too low to make it suitable for screening purposes in a high risk surgical population.
The effect of auditory input on impaired postural control perturbations was evaluated in two groups of stroke patients participating in a rehabilitation programme after a recent (< 12 months) and single episode of stroke, or less recent (> 12 months), and multiple episodes of stroke. Auditory input took the form of feedback signals generated by the forces actuated by the feet on a force platform in response to the patient's postural movements. Vibratory stimuli applied to the calf muscles induced sudden perturbations which the patients had to counteract to maintain an upright stance. The effect of auditory feedback in facilitating the maintenance of stance was measured in terms of sagittal torque variance (body sway) recorded on a force platform. In the presence of auditory feedback, body torque variance in response to perturbed posture was significantly reduced in the recent stroke group, whereas in the less recent stroke group the auditory feedback did not prove effective. Moreover, learning seems essential to utilize the auditory feedback.