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Biomedical subjects

M Hagberg

Publications and source records attributed to M Hagberg.

107 records · Page 6Linked to original sources
PubMed1984

Muscular endurance and electromyographic fatigue in myofascial shoulder pain.

An endurance test in shoulder flexion was made in 10 patients (median age 30 yr) with a history of shoulder-neck pain of at least one year's duration. No signs of inflammatory, rheumatic, or neuromuscular diseases were present among the patients but there was localized muscular pain and tenderness in the shoulder-neck region. In a sitting position the patients performed an endurance test of a 30 degree isometric shoulder flexion on both the left and right sides. EMG was recorded from the descending part of the trapezius muscle by surface electrodes and from the supraspinatus muscle by intramuscular wire electrodes. Myoelectric amplitude increase and mean power frequency (MPF) decrease with time during the endurance test were used as measures of fatigue development. All patients had a shorter duration of endurance on the more painful side. The endurance time was short in relation to the load. The regression between endurance time and MPF decrease was similar to that for healthy subjects. The short endurance time for the patients appears to be an effect of increased physiologic fatigability of the muscle which may be due to a change in its work capacity.

Adult↗
PubMed1983

A new, possibly serotonergic, neuron in the lamina of the blowfly optic lobe: an immunocytochemical and Golgi-EM study.

With a modified Golgi impregnation technique a new neuron type, with extensive tangential processes, was discovered in the optic lamina of the blowfly, Calliphora erythrocephala. This cell is unusual since the majority of its varicose processes reside in a layer distal to the synaptic layer of the lamina. Using antibodies to 5-HT it was found that this new cell type was 5-HT immunoreactive, and varicosities of Golgi impregnated neurons analyzed electron-microscopically contain dense core vesicles.

Animals↗
PubMed1982

Serum creatine kinase as an indicator of local muscular strain in experimental and occupational work.

Serum creatine kinase (SCK) was measured in ten subjects in the laboratory before and after the performance of bicycle ergometry and a lifting task. SCK was significantly increased 24 h and 48 h after the lifting work but not after the bicycle ergometry, although the work performed on the latter was four-times as great as on the former. The lifting work resulted in muscle pain and tenderness and, for six subjects, in clinical signs of shoulder tendinitis. In a field study, an increase in SCK was noted among assemblers/welders and cash-register operators, but not among controllers and forklift-truck drivers. A health interview revealed that musculo-skeletal complaints were most often located in the upper extremity in the cases of the assemblers/welders and the cash-register operators. It is proposed that the SCK increase during work is a result of a high local muscular load due to fatigue and energy depletion of muscle cells producing a greater efflux of muscle enzymes. The evaluation of SCK changes during work may be an important tool in occupational health for early detection of work tasks producing local muscular strain.

Adult↗
PubMed1982

Myoelectric power spectrum dependence on muscular contraction level of elbow flexors.

The influence of the strength of contraction on surface recorded myoelectric power spectra was studied for three elbow flexors. Four subjects performed brief (3-5 s) isometric contraction levels (5-80% MVC). The experiment was repeated 23-26 times on different days. The surface myoelectric signal was recorded from the biceps brachii, the brachialis and the brachioradialis. By fast Fourier transform the myoelectric power spectrum was computed. The mean power frequency (MPF) was calculated and used as a single estimate of the myoelectric power spectrum. The MPF was found to increase with contraction strength with low level contractions. At levels in excess of 25-30% of MVC, the MPF became independent of contraction level. This dependence of the MPF on low level contractions is explained by tissue filtering effects and the recruitment order and distribution of motor units.

Adult↗
PubMed1982

Antibody-dependent cell-mediated cytotoxicity against Escherichia coli O antigens.

Antibodies against Escherichia coli O antigen from rabbits immunized with formalin-killed bacteria were tested for cytotoxic capacity in an antibody-dependent cell-mediated cytotoxicity (ADCC) assay with human lymphocytes as effector cells and autologous papainized erythrocytes coated with O antigen as target cells. The cytotoxic titres were compared with the titres obtained with three methods of antibody quantitation. It was found that ADCC recorded antibodies with similar sensitivity as the enzyme-linked immunosorbent assay (ELISA) for IgG, but was much more sensitive than the ammonium sulphate precipitation (ASP) and indirect haemagglutination (IHA) using beta-mercaptoethanol reduced sera. The ADCC titres were found to correlate very well with the titres obtained with ASP, ELISA and IHA for IgG but not for IgM, which is in accordance with a previous notion that ADCC is primarily mediated via IgG antibodies. ADCC should be considered as a possible immunopathologic mechanism in renal parenchymal damage in connection with urinary tract infections.

Animals↗
PubMed1981

Occupational and individual factors in acute shoulder-neck disorders among industrial workers.

Twenty workers, consecutively attending the industrial health care centre for the first time with acute shoulder-neck pains, were subject to extensive rheumatological and ergonomic examinations. In seven patients congenital malformations for diseases causing musculoskeletal symptoms, or both, were probable aetiological factors. In the remaining 13 patients a significantly higher load was found on both shoulders (assessed by biomechanical film analysis) than in matched control. Age, anthropometric measures, muscle strength, or HLAB27 did not appear as significant predisposing factors. Most patients could return to work within a year.

Adult↗
PubMed1981

Muscular endurance and surface electromyogram in isometric and dynamic exercise.

In nine male volunteers, the endurance time for sustained isometric exercise (right-angle elbow flexion) and dynamic exercise (continuous concentric and eccentric elbow flexions) was measured at different contraction levels. Intermittent isometric exercises were also performed by four of the subjects in whom surface electromyographic elbow flexor recordings were obtained during the three types of exercise. A rapid decrease of the endurance time was seen at contraction levels above 15-20% of the maximum voluntary contraction for both the sustained isometric and dynamic exercise. There were no significant difference between the regression of the endurance time vs. the contraction level for the sustained isometric exercise and that of the dynamic exercise. However, the endurance time was enhanced in the intermittent isometric exercise compared with the sustained isometric exercise. The development of muscle fatigue was well correlated to change of the myoelectric rootmean-square amplitude and the mean power frequency. Differences in exercise did not significantly affect the relation between the time constant of the mean power frequency decrease and the endurance time.

Adult↗
PubMed1981

Electromyographic signs of shoulder muscular fatigue in two elevated arm positions.

Electromyographic signs of shoulder muscular fatigue were studied in abduction and forward flexion at right angle in the shoulder joint for seven subjects. The myoelectric signal was recorded by surface electrodes for the upper part of the trapezius muscle, the infraspinatus muscle, the middle and anterior part of the deltoid muscle and the biceps brachialis muscle. Bipolar wire electrodes were used for the supraspinatus muscle. By a moving window t-test the duration to the first significant increase of amplitude (RMS) or decrease of mean power frequency (MPF) were determined. The torque produced by the mass of the arm in the two studied elevated arm positions was found to exceed 10 per cent of the maximal voluntary contraction (MVC) for all subjects. For most subjects the supraspinatus and the upper part of the trapezius muscle, revealed significant signs of fatigue after five minutes in the two positions and short time constants of myoelectric amplitude changes. Furthermore electromyographic signs of fatigue developed within a minute for all subjects in the forward flexion (supraspinatus muscle) and in the abduction position (upper part of the trapezius muscle).

Adult↗
PubMed1979

The amplitude distribution of surface EMG in static and intermittent static muscular performance.

A measure of the variation of load on individual muscles or parts of muscles may be obtained by estimating the amplitude probability distribution function (APDF) of the myoelectric signal. In a study of elbow flexor muscular performance in static and intermittent static low level muscular contractions, the APDF was computed from the surface EMG obtained from the belly of the brachial biceps muscle. The APDF was also computed from the simultaneously recorded force signal. The APDF of the myoelectric signal and of the force signal were similar, indicating that the APDF of the myoelectric signal closely reflects the muscular load in non-fatiguing muscular contractions. The effect of the time constant in lowpass filtering when processing the surface EMG-signals was also studied. A suitable time constant appears to be in the range of 50-100 ms.

Adult↗
PubMed1979

Immunological aspects of pyelonephritis.

Several virulence factors, such as O and K antigens and capacity to attach to uroepithelial cells, seem to be required for Escheria coli to cause acute pyelonephritis. These factors induce an immune response, however, which can modify the course and clinical expression of the infection. During acute pyelonephritis, autoantibodies to the Tamm-Horsfall protein increase. These antibodies, which probably are evoked by a cross-reaction noted between structures of E. coli LPS and the Tamm-Horsfall protein, may add to the renal tissue engagement in interstitial nephritis caused by bacterial pyelonephritis.

Acute Disease↗
PubMedDate not supplied

Clinical assessment, prognosis and return to work with reference to work related neck and upper limb disorders.

OBJECTIVES: To describe the clinical assessment and management of work related neck and upper limb disorders. METHODS: A total of 65 references in English were found in Pub Med for the years 1980-2002 that dealt with clinical assessment, prognosis and return to work with reference to neck and upper limb original research that dealt with test performance in diagnostic procedures. Few studies were randomised studies of prognosis and return to work with reference to neck and upper limb disorders. RESULTS: The clinical assessment consists of the clinical and exposure history, the evaluation of the physical and laboratory findings. The physical examination should include the following steps: (1) inspection; (2) testing for range of motion (3) testing for muscle contraction pain and muscle strength (4) palpation of muscle tendons and insertions and (5) specific tests. The characteristics of clinical tests in terms of likelihood ratio for confirming and ruling out disease have to be considered for the diagnosis. The use of terms such as RSI (repetitive strain injuries) and CTD (cumulative trauma disorders) should be avoided. If the different musculoskeletal symptoms and signs do not completely comply with criteria for a disease, it is recommended to choose an ICD (International Classification of Disease) label that focuses on the symptoms rather than the pathology. The prognosis for most work related disorders are variable. The general experience is for non-specific neck and upper arm that pain and discomfort may be decreased but not eliminated in the majority of cases. It is important to start rehabilitation early. Long periods of sick leave are generally counterproductive. Disputed workers' compensation claims and an adverse work setting also are likely to impede successful rehabilitation. Since most patients with musculoskeletal disorders are also exposed to ergonomic stressors accommodation of the injured worker has to take the whole work system into account (task, technology, environment and organization). CONCLUSIONS: Despite the large number of patients with neck and upper limb disorders the scientific evidence for clinical assessment, to determine the prognosis and for successful procedures for return to work are few.

Arm↗