Biomedical subjects

M Långström

Publications and source records attributed to M Långström.

6 recordsLinked to original sources

PubMed1995

Anticipation in unipolar affective disorder.

Anticipation describes an inheritance pattern within a pedigree with an increase in disease severity and/or decrease in age at onset in successive generations. The phenomenon of anticipation has recently been shown to be correlated with the expansion of trinucleotide repeat sequences in a neuromuscular disease, various neurodegenerative disorders and mental retardation. We have studied parent-offspring differences in age at onset and disease severity in 31 pairs with unilineal inheritance of unipolar affective disorder (UPAD). Life-table analyses showed a significant decrease in survival to 1st episode of major depression in the offspring generation compared with the parental generation (P = 0.0007). There was also a significant difference in age at onset (P < 0.001) between parents and offsprings. The offspring generation experienced onset 15.6 years earlier and illness 1.5 x more severe than did the parent generation. Furthermore, there was a significant correlation (P < 0.05) in age at onset between parent and offspring generations. When we excluded pairs where the affected parent has an age of onset greater than the age of the child at the time of ascertainment (i.e., 23 pairs left), there was still a significant (P = 0.02) decrease in age at onset (8.4 years) and 1.5 x more severe disease in the offspring generation. No evidence for specific maternal or paternal inheritance was found. We found evidence of anticipation in 75-80% of this sample of unilineal family pairs of UPAD. Anticipation is, thus, an inheritance pattern in a large group of UPAD which suggests that the expansion of trinucleotide repeat sequences is a possible mode of inheritance in this group of UPAD. The findings of anticipation in this study of families with UPAD and previous findings in families with BPAD suggest that the variable expression of unstable expansions of trinucleotide repeats may turn out to be the basis of the continuum of liability in affective disorders.

Adolescent↗

PubMed1989

Knee extensor muscle function before and after reconstruction of anterior cruciate ligament tear.

Knee extensor performance, in 17 subjects with chronic anterior cruciate ligament (ACL) tear, was investigated preoperatively and on four different occasions postoperatively, using isokinetic measurements and electromyography of single maximum and repetitive manoeuvres. Preoperatively maximum mechanical output was comparatively low (injured leg), deteriorating further by 50% at fourteen weeks postoperatively. Endurance also falls markedly. Thereafter knee-extensor performance improved successively, mostly during intensive training (14-20 weeks postoperatively) irrespective of the training programme used. After one year, maximum performance was still unequal but the injured leg had achieved the "normal" preoperative noninjured value. Fatiguability/endurance level improved over preoperative values. Muscular work/integrated EMG was stable while EMG/t increased. Twenty weeks postoperatively quadriceps area was decreased to 69%, cf. noninjured control. The early postoperative loss of performance was evidently caused by loss of muscle mass. Neuromuscular relearning appears to be a sizable factor in later recovery. Isokinetic training does not offer any specific advantage in the early muscular rehabilitation after ACL reconstruction.

Adolescent↗

PubMed1987

Repeated isokinetic plantar flexions at different angular velocities.

Peak torque (PT), contraction work (CW) and mean power (CP) were measured for each of 200 repetitive isokinetic (maximum effort) plantar flexions. Simultaneous recording of integrated electromyograms (iEMG) were obtained from the three parts of the triceps surae muscle. Four tests at different angular velocities (30, 60, 120 and 180 degrees s-1 (degrees X s-1] were performed with at least 2 weeks between each test. The subjects were eight clinically healthy females (24-36 years). At all four angular velocities CW, CP and PT decreased steeply during the first approximately 70 contractions, followed by a steady-state level with no further significant decreases. The relative decreases of PT and CP were significantly smaller than for CW at all velocities. The relative CW decline increased with angular velocity; the relative PT and CP decreases were not velocity dependent. Also iEMG activity decreased in two phases during the 200 contractions and were on a significantly lower relative level at 180 degrees X s-1. However the reduction of range of motion was significantly greater at 180 degrees X s-1 and when the iEMG activity was compensated for this decrease the relative decreases in electromyographic activity were similar at the four angular velocities. The results indicated that CW was more sensitive to fatigue than PT and CP and that CW fatigue was dependent on angular velocity.

Adult↗

PubMed1985

Characteristics of repeated isokinetic plantar flexions in middle-aged and elderly subjects with special regard to muscular work.

Contractional work (CW), mean power (CP) and peak torque (PT) were recorded for each of up to 200 full range-of-motion (RoM) repetitive isokinetic (60 degrees X s-1) maximum effort plantar flexions. Subjects were 88 unselected clinically healthy males and females aged 40-44, 50-54 and 60-64 years with similar distributions of age and sex. Simultaneous recordings of integrated electromyograms (iEMGs) were obtained from the three heads of the m. triceps surae. Within approximately 50 contractions CW had decreased 36-21% for the different groups (by age and sex). The corresponding decreases for PT and CP were 28-14% and 25-13%, respectively. During the remaining part of the experiment only minor changes occurred. For CW but not for PT and CP reductions were negatively related to age while no sex differences were evident. Decreases in CW were significantly smaller in subjects physically active during leisure time than in those relatively inactive. Decreases in active range-of-motion provide an explanation for greater reductions in CW than in PT and CP. The iEMGs of the mm. gastrocnemii decreased significantly more than that of the m. soleus. Close associations between CW and iEMG were evident. Hence the chosen expression of output/input balance: CW/iEMG was nearly constant throughout the experiments. Results indicate that measurements of contractional work throughout the range-of-motion may provide more differentiated information on mechanical output during supposedly fatiguing dynamic manoeuvres than can recordings of maximum strength.

Adult↗

PubMedDate not supplied

Reconstruction of the anterior cruciate ligament. Long-term effects of different knee angles at primary immobilization and different modes of early training.

The clinical results in 29 patients who had undergone ACL reconstruction with quadriceps-patellar tendon graft over-the-top were studied at an average of 28 months postoperatively. Postoperative immobilization was at either 30 degrees (N = 17) or 70 degrees (N = 12) of knee flexion for 6 weeks. All patients then followed a common preparatory training program for 8 weeks. In the 14th postoperative week the patients were put on either progressive resistance training (N = 12) or isokinetic training (N = 17) for 6 weeks, after which all had identical training. Independent of primary knee immobilization angle or training regimens, no differences could be demonstrated with respect to stability, range of motion, function, or isokinetic mechanical output. For all patients, Lysholm knee function score improved from 60.5 to 93.6 (P less than 0.001) and activity level from 3.9 to 6.3 (P less than 0.001). Isokinetic peak torque, contractional work, and mean power of the quadriceps at 30, 90, and 180 deg/sec were lower in the injured compared to the noninjured leg (78% to 90%; P less than 0.01) both preoperatively and at followup, and there were no significant differences between the preoperative and follow-up values. Clinical stability improved (P less than 0.001) in 19 of the 29 patients (66%) and in 11 of those 17 patients with early isokinetic training (65%). Performance tests were normal in 23 of 29 patients (79%), with minor abnormalities in the rest.

Adolescent↗

PubMedDate not supplied

Isokinetic plantar flexor performance and fatiguability in peripheral arterial insufficiency. Effects of training vs. vascular surgery.

Seventeen men with peripheral arterial insufficiency and intermittent claudication (maximum walking tolerance less than 1000 m) underwent a bypass operation (group A, n = 8) or carried out simple exercises (repeated heel-raising) at home (group B, n = 9). The effects of treatment on the isokinetic performance of the plantar flexors and on fatiguability were assessed. Before treatment both groups had similarly low Doppler pressure indices, maximum performance and fatiguability level. Maximum walking tolerance was increased by treatment in both groups. Maximum plantar flexor output rose in group A, partly due to increased range of motion, but was only slightly changed in group B. Bypass surgery also led to increased electrical efficacy (contractional work/integrated electromyogram). Plantar flexor fatiguability normalized in six of the eight group A men, but in only a few from group B. Improvement in group B may be explained by specific adaptation of (mainly type 2B) muscle fibres. After bypass the increased capacity to remove combustion products may be the major reason for normalized fatiguability. Bypass surgery is preferable for most cases of intermittent claudication.

Arterial Occlusive Diseases↗