Strategies to promote well-being in small enterprises.
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Finland↗
Biomedical subjects
J Rantanen
Publications and source records attributed to J Rantanen.
Specific and innervation-regulated expression of the intermediate filament protein nestin at neuromuscular and myotendinous junctions in skeletal muscle.
The intermediate filament proteins nestin, vimentin, and desmin show a specific temporal expression pattern during the development of myofibers from myogenic precursor cells. Nestin and vimentin are actively expressed during early developmental stages to be later down-regulated, vimentin completely and nestin to minimal levels, whereas desmin expression begins later and is maintained in mature myofibers, in which desmin participates in maintaining structural integrity. In this study we have analyzed the expression levels and distribution pattern of nestin in intact and denervated muscle in rat and in human. Nestin immunoreactivity was specifically and focally localized in the sarcoplasm underneath neuromuscular junctions (NMJs) and in the vicinity of the myotendinous junctions (MTJs), ie, in regions associated with acetylcholine receptors (AChRs). This association prompted us to analyze nestin in neurogenically and myogenically denervated muscle. Immunoblot analysis disclosed a marked overall increase of accumulated nestin protein. Similar to the extrajunctional redistribution of AChRs in denervated myofibers, nestin immunoreactivity extended widely beyond the NMJ region. Re-innervation caused complete reversion of these changes. Our study demonstrates that the expression levels and distribution pattern of nestin are regulated by innervation, ie, signal transduction into myofibers.
Adult↗
Calf muscle atrophy and Achilles tendon healing following experimental tendon division and surgery in rats. Comparison of postoperative immobilization of the muscle-tendon complex in relaxed and tensioned positions.
We used a rat model to study the effects of immobilization of the calf muscle-tendon complex after an experimental Achilles tendon repair. Immobilizations of the complex in either a relaxed or tensioned position were compared by histochemical and morphometric analyses at the site of the tendon injury as well as in the gastrocnemius and soleus muscle bellies. The type of immobilization did not affect the healing of the tendon injury because no reruptures occurred in either of the treatment groups and the average tendon end-to-end distance did not differ between the groups. However, immobilization in a relaxed position led to a significantly more extensive fiber atrophy in the calf muscles. In clinical practice, these results suggest that rehabilitation after Achilles tendon surgery can be early and gradually tension- and load-increasing without a significant increase in the risk of rerupture of the tendon.
Achilles Tendon↗
Research challenges arising from changes in worklife.
Great challenges for occupational health research are set by the rapid changes in the world of work as a consequence of globalization, new technologies, demographic workforce changes, fragmentation of enterprises and work contracts, high time pressures, high demands for learning new skills, and growing worker mobility. The occupational health problems are of 2 types, the persistent and reemerging old problems of occupational injuries and diseases and new challenges from psychological stress, musculoskeletal disorders caused by computerized work, cognitive ergonomics in information-intensive work, the work ability of aging workers, and new trends in occupational allergies. The 3 roles of research, improvement of knowledge, improvement of understanding, and support of the development of work conditions in practice, all call for new initiatives in occupational health research. The new comprehensive strategy for the development and promotion of work ability has been found to respond effectively to these new needs.
Demography↗
Fasciotomy of the posterior femoral muscle compartment in athletes.
Over a period of 13 years fasciotomy was performed on 46 athletes with chronic pain located at the posterior femoral muscle compartment. The patients could be divided, according to the etiology, in two groups: exertion (26 patients) and trauma (20 patients). In the first group the symptoms appeared without any sudden trauma and most of the athletes competed in endurance sports (e.g. 16 long distance runners). In the second group there was a history of hamstring muscle rupture or recurrent injuries. The symptoms were dull pain, stiffness, cramps and weakness of the posterior thigh during and after training. Conservative treatment methods did not help to eliminate the symptoms during a long preoperative follow-up period. Posterior fasciotomy (minimum 20 cm) to the thigh was performed through one or two incisions. In four patients a simultaneous liberation, division or suturation of the muscle scar was done. The patients were followed up for 19 months and the results of the fasciotomy were good or excellent in 39 cases. Pain at the posterior thigh muscle compartment may sometimes become chronic and hamper the training of athletes. Fasciotomy seems to be an effective method to help these patients return to their previous level of sports.
Adolescent↗
Intramedullary fixation of high subtrochanteric femoral fractures: a study comparing two implant designs, the Gamma nail and the intramedullary hip screw.
OBJECTIVE: To compare two implants, the Gamma nail and the intramedullary hip screw (IMHS ), in the treatment of high subtrochanteric femoral fractures. STUDY DESIGN: Prospective, nonrandomized clinical study. METHODS: Eighty-seven consecutive patients with high subtrochanteric fractures of the Russell-Taylor Types 1A and 1B were treated with intramedullary fixation. The first fifty patients were treated with the Gamma nail and the next thirty-seven with the IMHS. The results of these operations were evaluated after a minimum follow-up of twelve months, and special emphasis was put on the complication rate. RESULTS: The number of noninfectious complications (intraoperative fractures, postoperative refractures and fixation failures) was significantly higher (p = 0.037) in the Gamma group (11 of 50, 22 percent) than in the IMHS group (2 of 37, 5 percent). The complication most often associated with the Gamma nail, postoperative fracture of the femoral shaft (six in our Gamma group), was not encountered with the use of the IMHS. The Gamma group also included three cases of intraoperative trochanteric extension of the fracture versus none in the IMHS group. The IMHS group included two mechanical fixation failures. CONCLUSIONS: The lower complication rate associated with the use of the IMHS implant could be attributable in part to the learning curve in the use of intramedullary implants. However, we consider that the evolution of the implant design contributes to the result.
Adolescent↗
Target levels--tools for prevention.
Although occupational exposure limits are sought to establish health-based standards, they do not always give a sufficient basis for planning an indoor air climate that is good and comfortable for the occupants in industrial work rooms. This paper considers methodologies by which the desired level, i.e., target level, of air quality in industrial settings can be defined, taking into account feasibility issues. Risk assessment based on health criteria is compared with risk-assessment based on "Best Available Technology" (BAT). Because health-based risk estimates at low concentration regions are rather inaccurate, the technology-based approach is emphasized. The technological approach is based on information on the prevailing concentrations in industrial work environments and the benchmark air quality attained with the best achievable technology. The prevailing contaminant concentrations are obtained from a contaminant exposure databank, and the benchmark air quality by field measurements in industrial work rooms equipped with advanced ventilation and production technology. As an example, the target level assessment has been applied to formaldehyde, total inorganic dust and hexavalent chromium, which are common contaminants in work room air.
Air Pollution, Indoor↗
Chronic compartment syndrome of the quadriceps femoris muscle in athletes. Diagnosis, imaging and treatment with fasciotomy.
BACKGROUND AND AIMS: Chronic quadriceps femoris muscle compartment syndrome is described. MATERIAL AND METHODS: Over a 13 year period nine patients were diagnosed, treated surgically by fasciotomy and followed up at a referral center specialized in sports traumatology. There were four power lifters, three body builders, one endurance walker and one cyclist in the series. The use of anabolic steroids was admitted by four of the nine patients. The patients complained of gradually worsening pain on the anterolateral side of the thigh during training. Initially the pain appeared only at the end of the training session. As the syndrome became more severe, the pain began earlier during exercise and gradually became worse preventing maximal training. Skeletal radiographs and ultrasound examinations were normal, except in two patients, who had a positive echography finding with local atrophy. MRI examination confirmed the US diagnosis. RESULTS AND CONCLUSIONS: As conservative treatment did not provide relief of symptoms, a fasciotomy anterior to the iliotibial tract was performed bilaterally to seven patients and unilaterally to two patients. Biopsies from the atrophied sites showed muscle cell necrosis. All the patients recovered well after the surgery and were able return to their original level of sport. The only complication of surgery was a postoperative hematoma in one patient, which delayed the beginning of the training, but did not result in any persistent complaints.
Adult↗
Mechanical failure of the intramedullary hip screw in a subtrochanteric femoral fracture.
The Gamma nail, an implant specifically designed for intertrochanteric and subtrochanteric femoral fractures, has been criticized for its high risk of secondary shaft fractures. A modified design, the intramedullary hip screw has recently been introduced to correct this complication. We present a case of mechanical failure of this new implant that occurred in a pathological subtrochanteric fracture. The centering sleeve of the implant became loose and migrated while the head screw penetrated the acetabulum. Refixation was successful.
Aged↗
Hypopigmented skin alterations resembling tuberous sclerosis in normal skin.
The significance of hypopigmented skin findings as manifestations of the gene for tuberous sclerosis (TS) in near relatives of TS patients is a difficult problem. We therefore studied the number and kind of whitish skin alterations found in 100 medical students and 100 school children. Ninety three percent of the former and 79% of the latter had some whitish lesions, many of them scars. Twenty percent of the adults and 12% of the children had roundish or oval macules larger than 10 mm in diameter, not known to be scars. In clinical practice with TS patients, our attention has been drawn to whitish raised masses or streaks in their first degree relatives. These were also found in study subjects so the significance of such lesions remains unclear. The role of Wood's light turned out to be questionable, far from pathognomonic for TS; 25% of all the whitish findings and 53% of the hypopigmented macules larger than 10 mm in diameter showed distinct or brilliant fluorescence under Wood's light.
Adult↗
Incidence of occupational asthma and persistent asthma in young adults has increased in Finland.
To investigate the incidence of occupational asthma and its relationship to new cases of persistent asthma, the data was collected from two national registers which cover practically all new cases of both diseases. In 1986 to 1993, the annual incidence of persistent asthma in adults (from 15 to 64 years) increased from 6,645 to 8,056 (21%). The incidence of asthma in women increased from 3,302 to 4,717 (43%). In the age group of 15 to 29 the increase was 91%, in 30 to 49 it was 60%, and in 50 to 64 the increase was 7%. Among men, the annual incidence remained stable. However, in the age group of 15 to 29 it increased by 87%, in 30 to 49 by 46%, while a decrease of 43% was detected in the age group of 50 to 64 years. During the same period, the annual incidence of occupational asthma increased from 227 to 386 (70%), from 109 to 185 (70%) in women and from 118 to 201 (70%) in men. In 1993 the population in Finland in the age range from 15 to 64 was 2.026 million. Thus, the incidence of persistent asthma was 0.4%. The proportion of newly diagnosed occupational asthma out of all new cases of asthma was 4.8%.
Adolescent↗
Modified Hauser operation for patellar instability. Immediate mobilization of 35 knees, a 5-8 year follow-up study.
We performed a follow-up examination of 35 knees with chronic patellar instability treated by a modified Hauser operation: medialization and distalization of the tibial tubercle without dorsal transfer, and fixation of the tubercle rigidly with 2 cortical screws. Cast immobilization was not used and the patients were allowed to mobilize the knee immediately. The follow-up period was 6 (5-8) years. 27 of 35 knees were excellent or good at follow-up, while 8 patients were more or less dissatisfied with the result. 5 knees had arthrosis at follow-up. No severe complications occurred, nor did the rate of minor complications differ from earlier reports.
Adolescent↗
Finnish Institute of Occupational Health Asbestos Program 1987-1992.
In 1987-1992, the Finnish Institute of Occupational Health (FIOH) implemented a nationwide asbestos program aimed at preventing asbestos-related risks in good cooperation with governmental authorities, industry, trade unions, the health care and insurance systems, and mass media. The goals were to minimize all exposure to asbestos, identify people exposed at work, and improve the diagnostics of asbestos diseases, especially cancers. The program entailed several concrete actions and extensive dissemination of information, training, services, and scientific research. As proposed by the State Asbestos Committee, new use of asbestos products was banned and strict regulations were applied to renovation and inspection of old buildings. The screening study of asbestos-induced diseases included 18,943 current and retired workers from house building, shipyard, and asbestos industries. Pleural and parenchymal changes were found in 4,133 persons (22%), who were referred to further clinical examinations as suspected cases of an occupational disease. It was estimated that past exposure of asbestos among the Finnish population of 5 million causes > 150 mesotheliomas and lung cancers annually, totalling > 2,000 asbestos-induced cancer deaths by the year 2010. Although several major control actions were made or started during the program, the bulk of the preventive work still lies ahead.
Asbestosis↗
Denervated segments of injured skeletal muscle fibers are reinnervated by newly formed neuromuscular junctions.
A muscle fiber normally receives its innervation at a single neuromuscular junction (NMJ). Transection of myofiber usually leaves one (abjunctional) stump denervated, while the other (adjunctional) remains innervated. To determine the mechanism of reinnervation of the abjunctional stumps, we transected the rat extensor digitorum muscle (EDL) below the site of the distalmost NMJ. Myofiber regeneration was followed for up to 56 days. Reinnervation began with the appearance of irregular acetylcholinesterase and alpha-bungarotoxin-positive deposits on abjunctional stumps after 10 to 15 days. These deposits later developed into more regular NMJ. The newly formed NMJ were innervated by sprouting axons which penetrated through the connective tissue scar separating the stumps. While denervated, the myofibers of the abjunctional segments underwent marked atrophy, which was reversed when reinnervation had ensued. In conclusion, we demonstrate for the first time that mature myofiber segments devoid of previous NMJ can induce both sprouting from intact axon terminals and formation of new "ectopic" NMJ on their own surface. This type of reinnervation is likely to occur only when myofibers are asymmetrically transected by a trauma. The signaling molecules possibly involved in this phenomenon are discussed.
Animals↗
Evaluation of research--a difficult but necessary task.
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Diffusion of Innovation↗
Satellite cell proliferation and the expression of myogenin and desmin in regenerating skeletal muscle: evidence for two different populations of satellite cells.
BACKGROUND: Regeneration of mature skeletal muscle recapitulates closely fetal myogenesis. It is initiated by activation of the reserve myogenic precursor cells, the satellite cells, which proliferate, differentiate into myoblasts expressing muscle-specific proteins, fuse into myotubes, and finally mature into myofibers. The MyoD family of transcription factors participates in the regulation of the complex phenomenon of myogenic differentiation during development and in vitro. The function of these transcription factors in the regeneration of injured mature skeletal muscle in vivo is, however, still unclear. EXPERIMENTAL DESIGN: To clarify the primary events in myogenic precursor cell activation, the expression of myogenin was examined in rats 1 to 48 hours after either a contusion injury to the gastrocnemius or after toxic injury to the soleus muscle. Myogenin mRNA expression was studied by Northern blot hybridizations, and the results were correlated with the onsets of the mitotic activity (i.e., incorporation of bromodeoxyuridine) of the satellite cells and of the production of the myogenin and MyoD1 proteins, as well as muscle-specific intermediate filament protein, desmin. RESULTS: Both forms of muscle injury produced myofiber necrosis, followed by the activation of the satellite cells. The first sign of myogenic differentiation, an increase in myogenin mRNA expression, occurred between 4 and 8 hours after injury. The first desmin-, MyoD1- and myogenin-positive myoblasts were seen after 12 hours, but satellite cell proliferation was not seen until 24 hours after the injury. CONCLUSIONS: The schedule of the events in our study contradicts the general concept that differentiation should follow proliferation. To explain this discrepancy, we propose that there are two populations of precursor cells: committed satellite cells, which are ready for immediate differentiation without preceding cell division, and stem satellite cells, which undergo mitosis before providing one daughter cell for differentiation and another for future proliferation.
Animals↗
Lumbar muscle fiber size and type distribution in normal subjects.
The macroanatomy of the clinically important lumbar muscles has recently been investigated in detail, whereas the information about their microscopic structure in healthy persons is still scanty. In this study we have analysed lumbar multifidus and erector spinae muscles from 21 previously healthy persons who died suddenly and were of working age (range 23-65 years, mean 44.7 years). The microscopic structure of myofibers within the lumbar muscles was found to be regionally uniform, which renders in vivo biopsies representative of the whole muscle bulk. Somewhat surprisingly, age did not significantly influence fiber type composition, fiber size, or proportion of nonmuscular tissue. There was a slight predominance of type 1 fibers. The size of type 1 fibers (mean lesser diameter 54.0 microns) corresponded to that in other skeletal muscles, with no significant sex difference (55.1/51.6 microns male/female). Selective type 2 fiber atrophy was a common finding in both sexes, but significantly less so in men (mean diameter 38.8/28.4 microns male/female). We suggest that the values of fiber type proportions and fiber size in the deep multifidus presented in this study can be used as reference values for healthy adults in the present society with limited physical activity.
Adult↗
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↗