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Biomedical subjects

M Lehto

Publications and source records attributed to M Lehto.

At least 55 records · Page 3Linked to original sources
PubMed1993

The lumbar multifidus muscle five years after surgery for a lumbar intervertebral disc herniation.

Biopsy specimens of the lumbar multifidus were obtained from 18 patients with lumbar disc herniation at operation and after a postoperative follow-up period of 5 years. The structure and morphometry of the muscle fibers were analyzed and these data were compared with intraoperative biopsy results and the clinical outcome of the operation. The main findings were: 1) on the basis of occupational handicap score 10 patients belonged in the "positive" and 8 in the "negative" outcome group; 2) the intraoperatively recorded selective type 2 muscle fiber atrophy and the extent of pathologic inner structure changes both decreased in the "positive" outcome group, whereas they persisted in the "negative" group; 3) grouping as a definite sign of reinnervation was seen in only two versus four patients of the "positive" versus "negative" outcome group; 4) the relative amount of adipose tissue within the muscle decreased more markedly in the "positive" outcome group. The authors propose that both inactivity and axonal injury (mainly of neurapraxia type) contribute to the selective type 2 atrophy and inner structure changes in disc patients' multifidus muscle. These pathologic structural changes correlated well with the clinical outcome, and most importantly they are reversible and can be diminished by adequate therapy.

Adult↗
PubMed1993

Atrophy and regeneration of rat calf muscles cause reversible changes in the number of nucleolar organizer regions. Evidence that also in nonproliferating cells the number of NORs is a marker of protein synthesis activity.

BACKGROUND: NORs are loops of DNA that transcribe to ribosomal RNA, and their number reflects the rDNA transcription, and, in this way, cell proliferation. EXPERIMENTAL DESIGN: The effect of muscle immobilization and remobilization on the number of nucleolar organizer regions (NORs) in the muscle cells and fibroblasts of rat calf muscles was studied histologically using a silver-staining technique (AgNOR). RESULTS: In muscle-cell nuclei, immobilization of 3 weeks produced a significant decrease in the number of AgNORs per nucleus. This phenomenon was reversible since, free remobilization of 4 weeks and especially intensified remobilization (free mobilization of 1 week plus treadmill running of 3 weeks) produced significant increase in the AgNOR counts. The treadmill running also produced a significant increase in the number of AgNORs in the muscle cells of contralateral (nonimmobilized) limbs. In intramuscular fibroblast nuclei, immobilization caused, in turn, a steady increase in the AgNOR count, the change being significant after 3 weeks. Free remobilization returned the count towards controls, and intensified remobilization returned it to the control level. CONCLUSIONS: Previous studies have shown that in the muscle cells immobilization decreases and remobilization (training) increases intracellular protein synthesis and that in the fibroblasts the opposite happens (immobilization increases and remobilization decreases intramuscular connective tissue formation). Our study gives indirect evidence that the number of NORs is a marker of ribosomal protein synthesis activity in non-proliferating cells. The cell-proliferation activity was proved to be zero using a proliferating-cell-nuclear-antigen technique.

Animals↗
PubMed1992

ABO blood groups and musculoskeletal injuries.

The distribution of the ABO blood groups was studied in 917 patients with specific musculoskeletal diagnoses. The ABO blood group distribution of patients with rupture of the Achilles tendon (P = 0.030) and of patients with chronic Achilles peritendinitis (P = 0.10) differed from the controls. The ABO blood group distribution was not associated with other musculoskeletal injuries studied. The blood group A/O ratio was 1.42 in the control population. In the group with rupture of the Achilles tendon this ratio was 1.0, and in the group with Achilles peritendinitis it was 0.70. The association between injuries of the Achilles tendon and the ABO blood group distribution was in accordance with an earlier report. There may be a genetic linkage between the ABO blood groups and the molecular structure of the tissue of Achilles tendons.

Achilles Tendon↗
PubMed1992

Diagnostic value of skin and laboratory tests in cow's milk allergy/intolerance.

The applicability of a panel of five skin and laboratory tests in the diagnosis of cow's milk allergy/intolerance (CMAI) was investigated. The tests used were prick and patch tests, RAST, basophil histamine release test (BHRT) and lymphocyte proliferation test (LPT). Twenty-two atopic children who had experienced either immediate or delayed cutaneous symptoms upon challenge with cow's milk (CM), and 12 non-milk-allergic controls with atopic dermatitis (AD) were included in the study. RAST, prick test, BHRT and LPT to CM and patch test to alpha-casein were positive in the CMAI group and non-milk-allergic atopic controls as follows: 59% and 33%, 57% and 0%, 55% and 17%, 77% and 17%, 33% and 0%. RAST, prick test and BHRT were more often positive in children exhibiting immediate reactions, and patch test and LPT more often positive in those having delayed reactions to CM. The panel of five tests detected 21/22 children with CMAI and gave false-positive results in 5/12 of non-milk allergic controls. The sensitivity and specificity of the panel in the diagnosis of CMAI were 95% and 58%, respectively.

Adolescent↗
PubMed1992

The effect of immobilization on myotendinous junction: an ultrastructural, histochemical and immunohistochemical study.

The effect of immobilization on the myotendinous junction of the calf muscles in the rat was studied histochemically, immunohistochemically and morphometrically with a transmission electron microscope. After 3 weeks of immobilization, the contact area between the muscle cells and tendineal collagen fibres was reduced by almost 50% in both type I (slow-twitch) and type II (fast-twitch) muscle fibres. The terminal finger-like processes of the muscle cells became shallow and cylindrical or were completely atrophied. Their basal membranes were slightly thickened. Histochemically, the most remarkable alteration in the myotendinous junction was the marked decrease in the sulphate containing glycosaminoglycans. In the basal lamina of the muscle fibres, the glycosaminoglycan and proteoglycan content was also reduced. Immunohistochemical analyses revealed that the amount of type III collagen was markedly increased on the myotendinous interface, but the amount and distribution of type I collagen was not affected by immobilization. These findings suggest that immobilization causes degenerative changes at the myotendinous junction, which, in turn, most likely decrease its tensile strength and may predispose it to rupture during activity.

Animals↗
PubMed1992

Ultrastructure and collagen composition of the myo-fascial junction in rat calf muscles.

The collagen composition and ultrastructural organization of the myo-fascial junction was studied using immunohistochemical techniques and electron microscopy. At the myo-fascial junction, a small amount of type-III collagen was found; however, the major collagen component was the type-I collagen. On the longitudinal sites of muscle cells, there were deep recesses and, within these, finger-like structures containing sarcomeres. In these recesses and in the finger-like structures of the myo-fascial junction, the sarcolemma was thickened (three times) in a similar way to the basal lamina at the myotendinous junction. Thin collagen fibers were closely associated with the thickened sarcolemma of the finger-like structures.

Animals↗
PubMed1992

Immediate and delayed hypersensitivity reactions to birch pollen in patients with atopic dermatitis.

We investigated immediate and delayed hypersensitivity to birch pollen in 10 patients with atopic dermatitis (AD) who had experienced a worsening of their eczema during the birch pollen season. The patients were prick- and patch-tested and antigen-induced basophil histamine release and lymphocyte proliferation were measured. 9/10 birch pollen-allergic patients proved positive in the histamine release test and the results correlated with specific IgE levels measured by RAST. Birch pollen antigen induced lymphocyte proliferation in 6/10 patients, but a positive patch test result was obtained in only one case. Both peripheral blood monocytes and purified epidermal Langerhans' cells were able to present birch pollen antigen to T cells, although Langerhans' s cells seemed to function less efficiently in this respect.

Allergens↗
PubMed1991

Maximal peak torque as a predictor of angle-specific torques of hamstring and quadriceps muscles in man.

This study assessed the relationship between the isokinetic peak torque (PT) (speed of movement 1.05 and 3.14 rads-1) and the angle-specific torques (ASTs) at 0.26 and 1.31 rad of knee flexion in multiple contractions of the quadriceps and hamstrings in 70 individuals with a chronic anterior cruciate ligament (ACL) insufficiency and 78 individuals with a chronic medial collateral ligament (MCL) insufficiency in one knee. At every test speed, the Pearson product moment correlation coefficients (r) between the PT and ASTs were highly significant (P less than 0.001) in the uninjured knees (r = 0.61-0.93) as well as in the knees with ACL (r = 0.61-0.87) and MCL (r = 0.74-0.91) insufficiency. In addition, in both groups the majority of the correlation coefficients exceeded 0.80, which is generally regarded as the threshold for the relationship to be considered clinically significant. Furthermore, using regression analysis, both extremities showed completely non-systematic distribution of the residuals. It is concluded that in healthy knees or knees with ACL or MCL insufficiency, the predictability of ASTs from PT was good, and, therefore, that AST analyses may offer little additional information about thigh muscle function to that obtained from a simpler and more commonly used measurement, the PT analysis.

Adult↗
PubMed1991

Macromolecular composition of the myotendinous junction.

The macromolecular composition of the myotendinous junction of the rat Achilles tendon was investigated. Heparan sulphate, chondroitin sulphate, and/or dermatan sulphate could be detected in the terminal processes of the muscle cells, but neither heparin nor keratan sulphate was present. The presence of hyaluronic acid was also questionable. High concentrations of sulphate containing glycosaminoglycans could be demonstrated both in the sarcolemma membranes and extracellular region. The main collagenous component in the myotendinous junction was type I collagen. Also small amounts of type III collagen was found at the myotendinous interface. In addition, high concentrations of fibronectin was present on the muscle cell surfaces of the junction. These results showed that myotendinous junction is histochemically and immunohistochemically a highly specified area rich in various polysaccharides. The high concentration of the polysaccharides in the myotendinous interface may increase the adhesive force between the muscle cell membrane and tendineal collagen fibrils and, by this way, it may be important in improving the elastic buffer capacity of the junction against loading.

Animals↗
PubMed1991

Lymphocyte proliferation test as a diagnostic aid in chromium contact sensitivity.

We investigated the clinical applicability of the lymphocyte proliferation test (LPT) in chromium contact sensitivity. 6 out of 8 chromium-sensitive patients were positive in the LPT, whereas none of 8 non-chromium-sensitive controls responded in vitro to tri- or hexavalent chromium compounds. LPT thus appeared to offer an additional diagnostic tool in chromium sensitivity. We also studied cellular interactions in 4 of our chromium-sensitive patients. Sensitized T-lymphocytes could be activated to proliferate only in the presence of accessory cells, of which epidermal Langerhans cells (LC) appeared more efficient than blood adherent cells.

Adult↗
PubMed1991

Electromyography and morphology during regeneration of muscle injury in rats.

Healing of the partially ruptured rat gastrocnemius muscle was studied correlating electromyographical findings with morphological changes. Fibrillation potentials and positive sharp waves were seen both proximal and distal to the injury 7 days after the injury and disappeared in the proximal part by day 14 and in the distal part by day 21. Late components of motor action potential were observed from day 14 onwards. Denervation was mainly myogenic, i.e. caused either by rupture of myofibres, whence the abjunctional stump lost its contact with the neuromuscular junction on the adjunctional stump, or by necrosis of the segment of the ruptured myofibre lying underneath the neuromuscular junction. Lesser extent of denervation was neurogenic, i.e. caused by damage to intramuscular nerve fibres. The reinnervation occurs either by regeneration of the necrotized myofibres, by regeneration of the severed nerves, or by collateral innervation of new neuromuscular junctions in the abjunctional stumps. The present study indicates that electromyography may be useful in the diagnosis and follow-up of skeletal muscle injuries.

Animals↗
PubMed1991

Morphology and histochemistry of the myotendineal junction of the rat calf muscles. Histochemical, immunohistochemical and electron-microscopic study.

The macromolecular composition and morphometry of the myotendineal junction (MTJ) of slow-twitch (type 1) and fast-twitch (type 2) muscle fibers were studied in gastrocnemius-soleus-Achilles unit of the rat. Proteoglycans and glycosaminoglycans, type III collagen, fibronectin and laminin could be detected at the myotendineal junction. Due to the membrane folding finger-like processes were seen at the MTJ. The processes of type 1 fibers were greater in size. However, due to the subdivisions the processes of type 2 muscle fibers had a significantly greater surface length per muscle cell diameter than type 1 fibers. The myotendineal endings of both fiber types had a characteristic basal lamina, which was about three times thicker than in the longitudinal site of the same muscle cells. The basal lamina of type 1 fibers at the MTJ was significantly thicker than that of type 2 fibers.

Achilles Tendon↗
PubMed1991

Localization of type I and III collagen and fibronectin production in injured gastrocnemius muscle.

The healing of muscle rupture consists of two simultaneous processes, regeneration of disrupted muscle fibers and production of connective tissue scar. These two processes are at the same time supportive to and competitive with each other. Their balanced progression is necessary for optimal healing. Synthesis of three connective tissue proteins, collagen types I and III and fibronectin, was analyzed during the regeneration process from 2 days to 3 weeks by Northern blot and in situ hybridization and immunohistochemistry. For this purpose a partial standard rupture of the gastrocnemius muscle was induced in 56 rats by a strike with a blunt spring-loaded hammer. Northern blot analysis of the specific mRNAs during the healing process revealed distinctly different expression patterns for fibronection and type I and III collagens. During the early stages (days 2 and 3) fibronectin, derived mainly from plasma, was abundant in the traumatized area, but local production of fibronectin mRNA by fibroblasts had also already started by day 2, closely followed by that of type III collagen. This early active synthesis of type III collagen and fibronectin was followed by a decrease after 1 week. The production of type I collagen mRNAs was activated somewhat later and remained elevated for at least 3 weeks. The muscle cells did not contain procollagen mRNAs. The observed sequence of connective tissue proteins reflects the particular function that each carries out during muscle wound healing (e.g., fibronectin in fibroblast trapping, type III collagen in plasticity/flexibility, and type I collagen in tensile strength).

Animals↗
PubMed1991

Structure and macromolecular composition of the myotendineal junction. Histochemical, immunohistochemical and electron microscopic study of the rat calf muscles.

The macromolecular composition and ultrastructure of the myotendineal junction (MTJ) of slow-twitch (type 1) and fast-twitch (type 2) muscle fibers were studied in the gastrocnemius-soleus-Achilles unit of the rat. Both proteoglycans and glycosaminoglycans, type III collagen, fibronectin and laminin could be detected at the MTJ. Due to membrane folding, finger-like processes were seen at the myotendineal junction. The processes of the type 1 fibers are greater in size, however, due to subdivisions, the processes of type 2 muscle fibers had a greater surface than type 1 fibers. The macromolecular composition is similar in both type 1 and type 2 muscle fibers.

Animals↗
PubMed1991

Structure and macromolecular composition of the myotendineal junction. Histochemical, immunohistochemical and electron microscopic study of the rat calf muscles.

The macromolecular composition and ultrastructure of the myotendineal junction (MTJ) of slow-twitch (type 1) and fast-twitch (type 2) muscle fibers were studied in the gastrocnemius-soleus-Achilles unit of the rat. Both proteoglycans and glycosaminoglycans, type III collagen, fibronectin and laminin could be detected at the MTJ. Due to membrane folding, finger-like processes were seen at the myotendineal junction. The processes of the type 1 fibers are greater in size, however, due to subdivisions, the processes of type 2 muscle fibers had a greater surface than type 1 fibers. The macromolecular composition is similar in both type 1 and type 2 muscle fibers.

Animals↗
PubMed1991

Healing of skeletal muscle injury: an ultrastructural and immunohistochemical study.

The healing of gastrocnemius muscle injury induced with a spring-loaded hammer in rats was analysed ultrastructurally and immunohistochemically. The ends of the ruptured myofibers retracted, which resulted in a central blood filled cavity. Central zone (CZ) later becomes occupied by granulation tissue scar. CZ is surrounded by a zone where myofibers are necrotized and phagocytosed by days 2-3. Complete regeneration within the preserved basal lamina (BL) cylinders takes place in 5-7 days. The regeneration of myofibers across the scar follows a pattern different from that within BL cylinders. Thin, often branched, myotubes grow out of the BL cylinders into the granulation tissue, where they extend between fibroblasts and collagen fibrils, in general oriented parallel to the preserved myofibers. The extension of the regenerating myotube seems to take place primarily by local synthesis in the growth cone. Fusing myoblasts provide nuclei, mostly along the sides but also occasionally at the tip of myotubes. Some myoblasts seem to derive from undifferentiated cells in the granulation tissue. By three weeks only a few thin myotubes had extended across the gap between the stumps of the ruptured myofibers. Growing myotubes appear to attach to the surrounding connective tissue by specialized structures, an attachment which evidently transmits contraction force across the gap, allowing use of the injured limb before the healing is complete.

Animals↗