Biomedical subjects

S E Larsson

Publications and source records attributed to S E Larsson.

At least 19 recordsLinked to original sources

PubMed2001

Outcome of surgery for cervical radiculopathy evaluated by determination of trapezius muscle microcirculation and electromyography.

Surgery for cervical radiculopathy was evaluated in 27 patients after anterior Cloward procedure (19 patients) or posterior decompression (eight patients). In addition, we examined 10 conservatively treated patients. Each patient was studied prospectively with regards to the effects on microcirculation in the local trapezius muscle during a fatiguing series of stepwise increased contractions. The right and left muscles were simultaneously examined pre-operatively and postoperatively after 9 months using laser-Doppler flowmetry and simultaneous surface electromyography (EMG). Preoperatively, a reduced microcirculation was found in the most painful side compared with the opposite side. This is in accordance with earlier reports on patients with chronic neurogenic neck pain, who also show reduced muscle tension on EMG. Postoperatively, the muscle blood flow became increased, but only in patients operated on via a posterior approach. A tendency at increased EMG-amplitude and reduced mean power frequency of the EMG was noted. These EMG signs of muscle fatigue suggest increased ability to exhaust the trapezius muscle postoperatively. The observed postoperative changes were consistently more frequent in the less painful side. We conclude from these objective measurements showing only a tendency at increased microcirculation and muscle tension postoperatively, that the effect on the trapezius muscle is limited.

Adult↗

PubMed1999

Suramin blocks growth-stimulatory effects of platelet-derived growth factor on malignant fibrous histiocytomas in vitro.

The pattern of susceptibility of malignant cells to the cytostatic drug suramin is not fully clarified. Therefore, in the present paper we have assessed the effects of suramin on the growth of eight cell lines derived from human malignant fibrous histiocytomas, by measuring DNA synthesis. The effect of suramin (10-200 microg/ml) on cells either unstimulated, or stimulated with platelet-derived growth factor (PDGF)-AA (10 ng/ml), PDGF-BB (10 ng/ml) or 10% fetal calf serum was studied. Four out of five cell lines unable to thrive without external growth factors showed growth inhibition by suramin. The two cell lines able to grow under serum-free conditions were unaffected by high-dose suramin. The exposure to suramin, at 200 microg/ml, abolished the growth stimulation caused by PDGF-AA and -BB. In contrast, a low dose of suramin (50 microg/ml), with or without PDGF, caused growth-stimulating effects in some cell lines. Our results indicate that high doses of suramin inhibit growth of malignant fibrous histiocytomas in vitro and that suramin exerts its growth-inhibitory effects on cells dependent on external growth factors. Low-dose treatment with suramin, however, may instead promote growth in both serum-dependent and -independent tumor cell lines.

Antineoplastic Agents↗

PubMed1999

Effects of human platelet-derived growth factor-AB on sarcoma growth in vitro and in vivo.

Platelet-derived growth factor (PDGF) has been proposed to play an important role in the growth of tumors. In order to study the effects of PDGF-AB on tumor growth in vivo, sarcoma-bearing mice were treated with PDGF-AB. The tumors, a malignant fibrous histiocytoma and an osteosarcoma, had functional PDGF receptors in vitro, as demonstrated by stimulation of PDGF-AB using a [3H]thymidine incorporation assay. Immunohistochemistry also revealed that both sarcoma xenografts expressed PDGF receptors. The tumor-bearing mice were given human PDGF-AB for 14 days, either continuously by an intraperitoneally placed mini-osmotic pump, or by daily injections. No effects on tumor growth in vivo were observed, as measured by tumor volume, autoradiography or cell cycle distribution. The histological appearance and ploidy of the tumors remained unaltered. The results indicate that, although the tumor cells are stimulated by PDGF-AB in vitro, the in vivo milieu or tumor growth pattern may render the tumors less susceptible to exogenously administered PDGF-AB in vivo.

Aged↗

PubMed1998

Human malignant fibrous histiocytomas in vitro: growth characteristics and their association with expression of mRNA for platelet-derived growth factor, transforming growth factor-alpha and their receptors.

Eight human malignant fibrous histiocytomas were examined in vitro, in order to relate their growth properties to mRNA expression for platelet-derived growth factor (PDGF), PDGF receptor (PDGF-R), transforming growth factor-alpha (TGF-alpha) and the epidermal growth factor receptor (EGF-R). Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that all cell lines expressed mRNA for PDGF-R alpha and/or PDGF-R beta; six cell lines expressed mRNA for the PDGF-A chain, with one cell line coexpressing PDGF-B chain mRNA; seven cell lines expressed mRNA for TGF-alpha whereas six cell lines expressed EGF-R mRNA. Conditioned medium from three cell lines contained PDGF; none of the cell lines released TGF-alpha. Two cell lines grew without serum requirements; whereas both expressed mRNA for PDGF, PDGF-R, TGF-alpha and EGF-R, other cell lines, unable to grow without serum, showed the same combination of growth factor/growth factor receptor expression. The two cell lines able to grow without serum were also shown to be stimulated by the addition of PDGF-BB. These findings show that simultaneous expression of mRNA for a growth factor and its receptor does not necessarily imply an autocrine or paracrine loop. However, two of our cell lines fulfil the requirements of possible PDGF-related autocrine and paracrine regulation.

Adult↗

PubMed1998

Visualization of chronic neck-shoulder pain: impaired microcirculation in the upper trapezius muscle in chronic cervico-brachial pain.

This study pertains to the 71 patients who had received a diagnosis of cervico-brachial pain syndrome after thorough clinical examination of a total series of 300 patients, who had been referred to the National Insurance Hospital in Tranås because of chronic neck pain that interfered with their ability to work. Changes in trapezius muscle blood flow and EMG were examined and related to the anamnesis and physical findings. The microcirculation in the upper part of the right and left trapezius muscles was examined simultaneously by using optical laser-Doppler single-fibres after insertion into the muscle directly via the skin. Continuous recordings were made during stepwise increased static contraction determined electro-myographically. Signal processing was performed on-line by computer. MRT of the cervical spine was performed in 12 patients. None showed nerve root affliction. Ten showed a bulging intervertebral disc and two, a narrowed nerve hole (lateral stenosis). The muscle blood flow (LDF) was significantly lower in the most painful side compared with the opposite side in the group of 41 patients with predominantly unilateral pain (21 women and 20 men). A lowered blood flow was also found when the 21 females in this group was compared with a normal control group of 20 healthy women. The patients had lower rms-EMG and EMG mean power frequency (MPF) in the painful side compared with the opposite side. A further lowering of the MPF was observed with induced fatigue. It was concluded that the chronic neck pain in cervico-brachial syndrome can become visualized by the finding of lowered blood flow of the trapezius muscle which seems to be an expression of the chronic neck pain.

Adult↗

PubMed1996

Single-fibre laser Doppler flowmetry and electromyography for evaluating microcirculation in forearm muscle during static and continuous handgrip contractions.

A technique is described for intramuscular measurement of muscle blood flow in the forearm, by using a 0.5-mm thin optical single-fibre for laser Doppler flowmetry (LDF) inserted percutaneously. Continuous recordings were performed of the brachioradial muscle during an 11-min series of alternating 1-min periods of increased static contraction and rest determined by an electronic handgrip forcemeter and surface electromyography (EMG) of the muscle. Stepwise increased handgrip contractions were performed at 10%, 20%, 30%, 40% and 50% maximal voluntary contraction (MVC). This was followed by a similar series of continuous contractions. Finally, an endurance test was performed with a handgrip force of 50% MVC maintained for as long as possible. A group of ten healthy men of different ages was studied. Signal processing was done on line by computer. Successive increases in rootmean square (rms)-EMG and a fall in the mean power frequency (MPF) of the EMG spectrum occurred during the series of static contractions, which evoked perceived local fatigue in the forearm. Muscle blood flow recorded simultaneously showed no change from resting level during contractions at 10%, 20% and 30% MVC, while at 40% and 50% MVC mean increases of 150% and 200% were recorded. Blood flows measured during the rest periods showed large variability with no significant changes. This was also found after continuous contractions of the same intensities. The endurance time was 1.2-3.5 min (mean 2.4 min). Muscle blood flow showed mean increases of 214%, 256% and 229% of resting level each minute of the maintained contraction. Nevertheless, EMG signs of local fatigue developed, such as a rise in rms-EMG and a fall in MPF, and the subject experienced local fatigue. To conclude, this technique of percutaneous, continuous LDF recorded, at high sensitivity, the microcirculation at different fluxes and EMG-defined muscle activity.

Adult↗

PubMed1996

Laser Doppler flowmetry: characteristics of a modified single-fibre technique.

The single-fibre percutaneous laser Doppler technique has been used in previous studies of intramuscular blood flow. This method facilitates studies of blood flow in deep tissue volumes and minimises the tissue trauma. The technique has been further developed with the aim of improving the signal quality. This has been accomplished by modifying the geometry of the fibre tip. By melting the fibre core material, lenses of different shapes are formed. Flat, spherical and 'pear'-type tips have been manufactured and are evaluated theoretically and experimentally. The paraxial theory cannot accurately predict the position of zones of highest irradiance. Therefore, a ray-tracing program has been developed in the C language, by means of which some of the optical properties of the modified fibre tips can be simulated. Iso-irradiance graphs and beam profiles are calculated for the three different fibre tips. Measured and calculated irradiance curves are used for evaluation of the properties of the ray-tracing model. The three types of fibre tips are also evaluated and compared in flow models. The sphere and pear-type probes show a higher flow sensitivity than the flat-end type. These improvements in flow sensitivity are interpreted as being related to the larger, strongly irradiated tissue volumes in front of the fibres. Intramuscular measurements with the pear-type probe show high sensitivities to induced blood flow changes.

Evaluation Studies as Topic↗

PubMed1996

A new single-fibre laser Doppler flowmeter based on digital signal processing.

A new laser Doppler flowmeter, based on a personal computer with a digital signal processor for detecting the blood perfusion in skeletal muscle, was designed and evaluated. An infrared laser diode (750 nm) fed a single optical fibre, 400 microns in diameter, which was introduced into the muscle. A PC equipped with a digital processing unit was used for emulation of the laser Doppler algorithm and for presentation of the measurement results. The Doppler signal power spectral density and corresponding flow values were visualized on the computer screen continuously in real-time, and could also be saved on the hard disk for off-line analyses. The graphic-user interface supported by Labwindows software made the system easy to use. It is possible to alter in the software the signal processing and the ways in which the signals and results are presented. The new system was evaluated by using a flow model as well as a mechanical model. The model studies showed linear relationships between particle velocity and flow in the range of 0-5 mm s-1. The system was also tested in measurements of the blood flow in the brachioradial muscle, and was found to have advantages over our previously used systems.

Algorithms↗

PubMed1995

Effects of psychophysiological stress on trapezius muscles blood flow and electromyography during static load.

Mental stress was induced by the Stroop colour word task (CW task) and the effects on the microcirculation and electromyography (EMG) in the upper portion of the trapezius muscle were studied during a series of fatiguing, standardized static contractions. A lowered blood flow of the skin recorded continuously by laser-Doppler flowmetry (LDF) was used as a stress indicator in addition to an elevated heart rate. Muscle blood flow was recorded continuously by LDF using a single optical fibre placed inside the muscle, and related to surface EMG. A group of 20 healthy women of different ages was examined. Recordings were made during a 50-min period in the following sequence: a 10-min series of alternating 1-min periods of rest and stepwise increased contraction induced by keeping the arms straight and elevated at 30, 60, 90 and 135 degrees with a 1-kg load carried in each hand; a 10-min recovery period without load; a repeated contraction series with simultaneous performance of the CW task; a second 10-min recovery period, and a second contraction series without CW task. Signal processing was done on line by computer. The LDF and root mean square (rms)-EMG values were calculated, as well as the EMG mean power frequency (MPF) for fatigue. The CW-task added to the contraction series caused an increase in the heart rate accompanied by a decrease in the blood flow to the skin and a 30% increase in the blood flow in the exercising muscle. Both returned to normal during the subsequent recovery period and showed normal levels during the final contraction series without CW. The rms-EMG showed a 20% increase that persisted during the final contraction series performed without CW. There was no influence on MPF. This CW has previously been shown to evoke an increased secretion of adrenaline from the adrenal medullae to the blood. The increased blood flow in the exercising muscle would therefore appear to have been caused by beta-adrenoceptor vasodilatation, and the fall in the blood flow in the skin by alpha-adrenoceptor vasoconstriction. The findings may have implications for work situations characterized by repetitive static loads to the shoulder muscles and psychological stress.

Adult↗

PubMed1995

Microcirculation in the upper trapezius muscle during sustained shoulder load in healthy women--an endurance study using percutaneous laser-Doppler flowmetry and surface electromyography.

Microcirculation in the upper portion of the trapezius muscle was measured percutaneously in a group of 16 healthy women of different ages by continuous laser-Doppler flowmetry (LDF) in relation to electromyography (EMG) during an endurance test. During the measurements the subject kept her arms straight and elevated at 45 degrees in the scapular plane and held a 1-kg load in each hand as long as possible. This was followed by rest with the arms hanging and carrying no load. The 10-min recording period comprised 1-min initial rest followed by the endurance test and then recovery. Signal processing was done by computer on line. The LDF and root-mean-square (rms) EMG signals were normalized. Spectrum analyses of EMG mean power frequency (MPF) were performed. The amount of load produced was on average 2,267 (SD 939) N.m.s, i.e. shoulder torque x time expressed as Newton meter seconds, and the endurance time was 4.3 (SD 1.20) min. The rms-EMG as well as the LDF increased significantly during endurance, both when related to endurance time and to amount of load. The MPF showed no significant changes. The mean total increase in muscle blood flow was 175% of that recorded in the initial rest period. The average increase per each 10 s of contraction was 2.9%. Maximum was reached during the 1st min of recovery followed by a fall to the base level that was reached within 77 s on average. The amount of load produced and the blood flow increase was smaller than that found in a separate study of men, indicating a lower functional capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Measurement by laser-Doppler flowmetry of microcirculation in lower leg muscle at different blood fluxes in relation to electromyographically determined contraction and accumulated fatigue.

Single-fibre percutaneous laser-Doppler flowmetry (LDF) of the tibialis anterior muscle was performed continuously for measurement of the microcirculation during different blood fluxes, as well as in relation to different muscle activities and fatigue determined electromyographically (EMG). The laser-Doppler power spectrum density function was studied in a frequency range of 0-8.2 Hz as representing the blood flow most selectively. Reduced blood flow from tourniquet inflation caused a decrease in signal power density, compared to that of intact blood flow at rest. During postocclusion reactive hyperaemia an increased signal power was recorded. This reached its maximum within 4.4 (SD 1.88) s after deflation of the tourniquet. The different fluxes were recorded at high sensitivity and disturbances were small. Periods of 1-min static dorsi-flexion of the foot at 10, 20, 30, 40, and 50% MVC (maximal voluntary contraction) with 1-min rest between were associated with a significant increase in LDF, the recordings obtained during the rest periods showing a tendency towards an increase. A decrease in the EMG mean power frequency (MPF) indicated accumulated fatigue. The LDF for the rest periods that followed upon continuous contractions up to the same MVC levels showed a tendency towards an increase but variability was large. With further development, these techniques may be useful in the evaluation of insufficiency of the peripheral circulation.

Adult↗

PubMed1994

Work-related persistent neck impairment: a study on former steelworks grinders.

The possibility of a work-acquired acceleration of the physiologic degenerative process affecting the cervical spine was studied in 15 Swedish former steelworks grinders. They were compared clinically with 15 age- and sex-matched white collar workers and radiographically compared with another reference group of matched individuals with light work. The now obsolete grinding machine placed extremely heavy load on the neck and shoulders, to the extent that all grinders had to retire after varying numbers of years and take a disability pension, or take up light work because of persistent pain and stiffness in the neck-shoulders; in this series after on average 8 (2-16) years. At follow-up 18 (11-29) years later, their mean age was 56 (48-62) years. All had persistent neck pain and stiffness and widespread paresthesia. Goniometric recordings showed impairment of active neck motion range as well as motion speed in all three planes and an altered motion pattern. Vibration sense was decreased in all extremities. Radiographically, foraminal encroachment was significantly increased both from spondylosis and spondylarthrosis, while disc height, lordosis, and alignment did not differ from that in the reference group of individuals with light work.

Humans↗

PubMed1993

Continuous percutaneous measurement by laser-Doppler flowmetry of skeletal muscle microcirculation at varying levels of contraction force determined electromyographically.

Laser-Doppler flowmetry (LDF) and electromyography (EMG) were used simultaneously for measuring skeletal muscle blood perfusion in relation to static load and fatigue. Percutaneous single-fibre LDF and bipolar surface EMG of the trapezius muscle were performed continuously during a 10-min series of alternating periods of static contractions and rest, each of 1-min duration. The muscle was exposed to static load expressed as shoulder torque, by keeping the arms straight and elevated at 30, 60, 90 and 135 degrees. On-line computer processing of the LDF and EMG signals made possible the interpretation of the relationship between the perfusion and the activity of the muscle. The LDF and root mean square (rms)-EMG were normalized by using the average value of the serial examinations of each individual as a reference value. Spectrum analyses of EMG showed the lowest variability for median frequency (MDF) in the frequency range 10-1000 Hz and mean power frequency (MPF) at 2-1000 Hz. The LDF power spectrum density during low (muscle rest) and high (high-force muscle contraction) perfusion indicated that disturbances were small when measurements were performed during sustained static contraction with as little movement as possible. Vasomotion, i.e. rhythmic variations in the blood flow, were present and showed a frequency of 5-6 cycles.min-1. Application of a tourniquet to the upper arm caused an arrest of the microcirculation in the distally situated brachioradial muscle which was followed by a postischaemic hyperaemia upon removal of the torniquet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Microcirculation in the upper trapezius muscle during varying levels of static contraction, fatigue and recovery in healthy women--a study using percutaneous laser-Doppler flowmetry and surface electromyography.

Microcirculation in the upper portion of the trapezius muscle was measured percutaneously by continuous laser-Doppler flowmetry (LDF) during two 10-min series of alternating 1-min periods of static contraction and rest determined electromyographically (EMG). Stepwise increased contraction was induced by keeping the arms straight and elevated at 30, 60, 90 and 135 degrees, which was repeated with a 1-kg load carried in each hand. Thereafter, fatigue and recovery were recorded while the subject kept her arms straight and elevated at 45 degrees carrying the 1-kg hand load as long as possible, followed by rest with arms hanging and no load. A group of 16 healthy women of different ages was studied. Signal processing was done on line using a 386 SX computer. The LDF- and root-mean-square (rms) EMG signals were normalized. Spectrum analyses of EMG mean power frequency (MPF) and median spectrum frequency were performed. The rms-EMG increased significantly with an increase in the calculated shoulder torque (r = 0.75). Accumulated local fatigue was indicated by a decrease in MPF with increased shoulder angle and added load (r = -0.54). Blood flow increased with increased shoulder angle (r = 0.82, with hand load r = 0.62) and with increased shoulder torque (r = 0.72), and also showed a significant increase with increased EMG activity (r = 0.74). The LDF showed a negative correlation to MPF (r = -0.67), with increased values when MPF was lowered. During the endurance test, a moderate increase of LDF occurred which reached its maximum during the 1st min of recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Dynamic posturography among patients with common neck disorders. A study of 15 cases with suspected cervical vertigo.

We have studied a consecutive series of 15 patients with long-lasting common neck pain combined with vertigo and/or unsteadiness by dynamic posturography with the head in different positions. The evaluation of disturbed equilibrium was done in the anteroposterior direction. Results were compared with 15 sex- and age-matched healthy controls and 10 patients with long-lasting neck complaints without vertigo or unsteadiness. The otoneurological, audiometrical, and electronystagmographical examination was normal in all individuals. The dynamic posturography on a sway-referenced forceplate showed significantly lower equilibrium scores in the patients with vertigo/unsteadiness than in the controls when recorded in neutral position of the head, in rotation and in lateral flexion. The patients with vertigo also had significantly lower equilibrium scores in the position most prone to elicit their vertigo/unsteadiness as compared with the patients with only neck pain. Dynamic posturography was found to be of diagnostic value, indicating the presence of vertigo of cervical origin.

Adult↗

PubMed1992

Electromyographic changes in work-related myalgia of the trapezius muscle.

In 11 patients, all women, 21-55 years of age, with unilateral work-related myalgia of the trapezius muscle, the right and left trapezius muscles were examined simultaneously for electromyogram (EMG) signs of localized muscle fatigue. All patients were tested with 0-kg hand load for 5 min, holding the arms straight at 90 degrees of elevation in the scapular plane. Only 4 of the patients tolerated exposure to higher load levels. They were tested with 1 kg hand load for 3 min and 2 kg hand load for 2 min, with a period of rest of 30 min between the trials. The EMG mean power frequency (MPF) and root mean square (rms) were calculated. Data were normalized with the initial value as a reference and regression analyses were performed. On both sides a decrease of MPF and an increase of rms were found with increasing time and load, i.e. classical EMG signs of localized muscle fatigue. Compared with the nonaffected side smaller changes were found on the affected side, possibly due to pain inhibition, impaired microcirculation and biochemical changes along the muscle fibres. At 0-kg hand load we found no change of MPF on either side despite subjective feelings of fatigue and pain. We interpreted these findings as an indication of reduced capacity of the affected trapezius muscle to sustain static load with early development of pain-associated local fatigue.

Adult↗

PubMed1992

Locomotion status and costs in destructive rheumatoid arthritis. A comprehensive study of 82 patients from a population of 13,000.

Clinical manifestations (locomotion score) and annual costs were studied in a population-based cohort of 82 patients with rheumatoid arthritis fulfilling five to eight American Rheumatological Association's (ARA) criteria. The total costs were SEK 4.9 million: respectively 56 and 44 percent direct and indirect costs. The costs were correlated with total, as well as subjective and objective, locomotion scores, which assess separately impairment, disability, and handicap from the disease (WHO 1980). Patients below 65 years had higher costs-predominantly as an indirect cost due to loss of work-than older patients. Elderly rheumatoid arthritis (RA) patients had a low score and high costs for medical and social services' care, but they had no indirect costs. Patients with a low locomotion score had received previous hospital treatment averaging 89 days. The need of hospital treatment was strongly correlated with low locomotion score. The mean annual patient's costs were about SEK 60,000, but above this for younger patients. When compared with patients with a mild affliction (score 91-100), patients with moderate manifestations, i.e., with a score of 70-90, had five times higher costs, whereas those with severe manifestations, with a score below 50, had 20 times higher costs.

Adult↗

PubMed1992

Work-related chronic neck impairment. Neck motion analysis in female traverse crane operators.

Twenty-one female steel industry traverse crane operators with long-term sick-leave (3 (1-8) years) due to chronic neck disability underwent careful analysis of case history, physical status and electrogoniometric three-dimensional recordings of active neck motion. Results were compared with those from working female crane operators having identical work posture and tasks and, further, with a group of working female clerks. The sick-listed crane operators had previous frequent contacts with the primary health care because of complaints from the neck and back. In comparison with the reference groups, the sick-listed crane operators showed tenderness of the trapezius and levator scapulae muscles and a short neck stature in combination with impaired active neck motion range with reduced motion speed. The motion pattern was however unchanged. The findings are consistent with the clinical picture of chronic neck myalgia that persisted despite long-term absence from the previous exposure to high static work load upon the neck-shoulders.

Adult↗