umu.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Lorentzon, Ronny
Alternative names
Publications (10 of 56) Show all publications
Ferry, T., Bergström, U., Hedström, E. M., Lorentzon, R. & Zeisig, E. (2014). Epidemiology of acute knee injuries seen at the Emergency Department at Umeå University Hospital, Sweden, during 15 years. Knee Surgery, Sports Traumatology, Arthroscopy, 22(5), 1149-1155
Open this publication in new window or tab >>Epidemiology of acute knee injuries seen at the Emergency Department at Umeå University Hospital, Sweden, during 15 years
Show others...
2014 (English)In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 22, no 5, p. 1149-1155Article in journal (Refereed) Published
Abstract [en]

PURPOSE: To describe the incidence and injury distribution of knee injuries in the general population of a European setting. METHODS: Retrospective study of all knee injuries registered at the Emergency Department at Umeå University Hospital, Sweden, during 1995-2009 in relation to age, sex, diagnosis, location and activity at the time of injury, mechanism of injury, and treatment and/or follow-up plan. RESULTS: During 1995-2009, 12,663 knee injuries were registered, 8 % of all injuries. The incidence of knee injuries resulting in a visit to the Emergency Department was six cases per 1,000 person years. One-third of all injuries occurred during sports. And 30 % were 15-24 years. More men than women were injured during sporting activities and women were mostly injured during transportation. CONCLUSION: Knee injuries in a general population are common and the injury distribution varies with age and sex. Sports activities and young age were prominent features of the injured population. LEVEL OF EVIDENCE: IV.

Place, publisher, year, edition, pages
Springer, 2014
Keywords
knee injury, general population, epidemiology, incidence, sports
National Category
Orthopaedics Sport and Fitness Sciences Surgery
Identifiers
urn:nbn:se:umu:diva-79211 (URN)10.1007/s00167-013-2555-3 (DOI)000334757600026 ()23740325 (PubMedID)
Available from: 2013-08-13 Created: 2013-08-13 Last updated: 2018-06-08Bibliographically approved
Song, Y., Stål, P. S., Yu, J.-G., Lorentzon, R., Backman, C. & Forsgren, S. (2014). Inhibitors of endopeptidase and angiotensin-converting enzyme lead to an amplification of the morphological changes and an upregulation of the substance P system in a muscle overuse model. BMC Musculoskeletal Disorders, 15, 126
Open this publication in new window or tab >>Inhibitors of endopeptidase and angiotensin-converting enzyme lead to an amplification of the morphological changes and an upregulation of the substance P system in a muscle overuse model
Show others...
2014 (English)In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 15, p. 126-Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: We have previously observed, in studies on an experimental overuse model, that the tachykinin system may be involved in the processes of muscle inflammation (myositis) and other muscle tissue alterations. To further evaluate the significance of tachykinins in these processes, we have used inhibitors of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE), substances which are known to terminate the activity of various endogenously produced substances, including tachykinins.

METHODS: Injections of inhibitors of NEP and ACE, as well as the tachykinin substance P (SP), were given locally outside the tendon of the triceps surae muscle of rabbits subjected to marked overuse of this muscle. A control group was given NaCl injections. Evaluations were made at 1 week, a timepoint of overuse when only mild inflammation and limited changes in the muscle structure are noted in animals not treated with inhibitors. Both the soleus and gastrocnemius muscles were examined morphologically and with immunohistochemistry and enzyme immunoassay (EIA).

RESULTS: A pronounced inflammation (myositis) and changes in the muscle fiber morphology, including muscle fiber necrosis, occurred in the overused muscles of animals given NEP and ACE inhibitors. The morphological changes were clearly more prominent than for animals subjected to overuse and NaCl injections (NaCl group). A marked SP-like expression, as well as a marked expression of the neurokinin-1 receptor (NK-1R) was found in the affected muscle tissue in response to injections of NEP and ACE inhibitors. The concentration of SP in the muscles was also higher than that for the NaCl group.

CONCLUSIONS: The observations show that the local injections of NEP and ACE inhibitors led to marked SP-like and NK-1R immunoreactions, increased SP concentrations, and an amplification of the morphological changes in the tissue. The injections of the inhibitors thus led to a more marked myositis process and an upregulation of the SP system. Endogenously produced substances, out of which the tachykinins conform to one substance family, may play a role in mediating effects in the tissue in a muscle that is subjected to pronounced overuse.

Place, publisher, year, edition, pages
BioMed Central, 2014
Keywords
muscle, exercise, overuse, myositis, tachykinin, substance P
National Category
Rheumatology and Autoimmunity Sport and Fitness Sciences
Identifiers
urn:nbn:se:umu:diva-88030 (URN)10.1186/1471-2474-15-126 (DOI)000335189300003 ()24725470 (PubMedID)
Available from: 2014-04-22 Created: 2014-04-22 Last updated: 2018-06-08Bibliographically approved
Song, Y., Forsgren, S., Yu, J., Lorentzon, R. & Stål, P. (2012). Effects on contralateral muscles after unilateral electrical muscle stimulation and exercise. PLoS ONE, 7(12), e52230
Open this publication in new window or tab >>Effects on contralateral muscles after unilateral electrical muscle stimulation and exercise
Show others...
2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 12, p. e52230-Article in journal (Refereed) Published
Abstract [en]

It is well established that unilateral exercise can produce contralateral effects. However, it is unclear whether unilateral exercise that leads to muscle injury and inflammation also affects the homologous contralateral muscles. To test the hypothesis that unilateral muscle injury causes contralateral muscle changes, an experimental rabbit model with unilateral muscle overuse caused by a combination of electrical muscle stimulation and exercise (EMS/E) was used. The soleus and gastrocnemius muscles of both exercised and non-exercised legs were analyzed with enzyme-and immunohistochemical methods after 1, 3 and 6 weeks of repeated EMS/E. After 1 w of unilateral EMS/E there were structural muscle changes such as increased variability in fiber size, fiber splitting, internal myonuclei, necrotic fibers, expression of developmental MyHCs, fibrosis and inflammation in the exercised soleus muscle. Only limited changes were found in the exercised gastrocnemius muscle and in both non-exercised contralateral muscles. After 3 w of EMS/E, muscle fiber changes, presence of developmental MyHCs, inflammation, fibrosis and affections of nerve axons and AChE production were observed bilaterally in both the soleus and gastrocnemius muscles. At 6 w of EMS/E, the severity of these changes significantly increased in the soleus muscles and infiltration of fat was observed bilaterally in both the soleus and the gastrocnemius muscles. The affections of the muscles were in all three experimental groups restricted to focal regions of the muscle samples. We conclude that repetitive unilateral muscle overuse caused by EMS/E overtime leads to both degenerative and regenerative tissue changes and myositis not only in the exercised muscles, but also in the homologous non-exercised muscles of the contralateral leg. Although the mechanism behind the contralateral changes is unclear, we suggest that the nervous system is involved in the cross-transfer effects.

Place, publisher, year, edition, pages
Public Library Science, 2012
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:umu:diva-64452 (URN)10.1371/journal.pone.0052230 (DOI)000312794500120 ()
Available from: 2013-02-05 Created: 2013-01-29 Last updated: 2018-06-08Bibliographically approved
Spang, C., Scott, A., Danielson, P., Lorentzon, R. & Forsgren, S. (2012). VGluT2 and NMDAR1 expression in cells in the inflammatory infiltrates in experimentally induced myositis: evidence of local glutamate signaling suggests autocrine/paracrine effects in an overuse injury model. Inflammation, 35(1), 39-48
Open this publication in new window or tab >>VGluT2 and NMDAR1 expression in cells in the inflammatory infiltrates in experimentally induced myositis: evidence of local glutamate signaling suggests autocrine/paracrine effects in an overuse injury model
Show others...
2012 (English)In: Inflammation, ISSN 0360-3997, E-ISSN 1573-2576, Vol. 35, no 1, p. 39-48Article in journal (Refereed) Published
Abstract [en]

It is not known whether a glutamate signaling system is involved in muscle inflammation (myositis). In the present study, we examined this question in the soleus muscle in a laboratory model of myositis resulting from repetitive overuse induced by electrical stimulation and injection of pro-inflammatory substances. Sections of rabbit soleus muscle with an induced myositis, i.e., exhibiting infiltration of inflammatory cells, were examined immunohistochemically using antibodies against vesicular glutamate transporter VGluT2 and the glutamate receptor NMDAR1. In situ hybridization for demonstration of VGluT2 mRNA was also performed. Specific reactions for both VGluT2 and NMDAR1 could be observed immunohistochemically in the same cells. In situ hybridization demonstrated the occurrence of VGluT2 mRNA in the cells. Double staining showed that the VGluT2 reactions were detectable in cells marked with T cell/neutrophil marker and in cells expressing eosinophil peroxidase. These data suggest the occurrence of previously unknown glutamate-mediated autocrine/paracrine effects within the inflammatory infiltrates during the development of muscle inflammation.

National Category
Rheumatology and Autoimmunity
Identifiers
urn:nbn:se:umu:diva-41361 (URN)10.1007/s10753-010-9287-z (DOI)000300550900005 ()21193952 (PubMedID)
Available from: 2011-03-23 Created: 2011-03-23 Last updated: 2018-06-08Bibliographically approved
Nordström, P., Eklund, F., Björnstig, U., Nordström, A., Lorentzon, R., Sievänen, H. & Gustafson, Y. (2011). Do both areal BMD and injurious falls explain the higher incidence of fractures in women than in men?. Calcified Tissue International, 89(3), 203-210
Open this publication in new window or tab >>Do both areal BMD and injurious falls explain the higher incidence of fractures in women than in men?
Show others...
2011 (English)In: Calcified Tissue International, ISSN 0171-967X, E-ISSN 1432-0827, Vol. 89, no 3, p. 203-210Article in journal (Refereed) Published
Abstract [en]

The higher incidence of fractures in women than in men is generally attributed to the lower areal bone mineral density (areal BMD, g/cm(2)) of the former. The purpose of the present study was to investigate both areal BMD and injurious falls as risk factors for fractures. In a first cohort, areal BMD was measured in 5,131 men and women (age range 40-95 years). In a second cohort, consisting of 26,565 men and women (age range 40-69 years), a health survey was conducted including questions about lifestyle and medication. Main outcome measures included validated prospective injurious falls and fractures in both cohorts. The higher areal BMD and femoral neck BMD in men compared to women (P < 0.001) were explained by a higher diameter of the femoral neck. Importantly, the diameter of the femoral neck was not associated with fractures in either sex (hazard ratio [HR] 0.94-1.04, P > 0.05 for all), suggesting that a higher areal BMD and lower incidence of osteoporosis in men do not explain their lower incidence of fractures. In contrast, women were more prone to sustain injurious falls than men in both cohorts investigated (HR for women = 1.61 and 1.84, P < 0.001 for both), resulting in a higher incidence of fractures (HR for women = 2.24 and 2.36, P < 0.001 for both). The number of injurious falls and fractures occurring each month during the study period showed a very strong correlation in both women (r = 0.95, P < 0.00001) and men (r = 0.97, P < 0.00001). In summary, low areal BMD, and thus osteoporosis, may not explain the higher fracture incidence in women than in men. Instead, a higher incidence of injurious falls in women was strongly associated with the higher fracture risk.

Place, publisher, year, edition, pages
Springer, 2011
Keywords
Falling, Fracture, Prevention, Bone density, Osteoporosis
National Category
Geriatrics Sport and Fitness Sciences
Identifiers
urn:nbn:se:umu:diva-47981 (URN)10.1007/s00223-011-9507-z (DOI)21667164 (PubMedID)
Available from: 2011-10-05 Created: 2011-10-05 Last updated: 2018-06-08Bibliographically approved
Andersson, G., Backman, L., Scott, A., Lorentzon, R., Forsgren, S. & Danielson, P. (2011). Substance P accelerates hypercellularity and angiogenesis in tendon tissue and enhances paratendinitis in response to Achilles tendon overuse in a tendinopathy model. British Journal of Sports Medicine, 45(13), 1017-1022
Open this publication in new window or tab >>Substance P accelerates hypercellularity and angiogenesis in tendon tissue and enhances paratendinitis in response to Achilles tendon overuse in a tendinopathy model
Show others...
2011 (English)In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 45, no 13, p. 1017-1022Article in journal (Refereed) Published
Abstract [en]

Background Tenocytes produce substance P (SP) and its receptor (neurokinin-1 receptor (NK-1R) is expressed throughout the tendon tissue, expecially in patients with tendinopathy and tissue changes (tendinosis) including hypercellularity and vascular proliferation. Considering the known effects of SP, one might ask whether SP contributes to these canges.

Objectives To test whether development of tendinosislike changes (hypercellularity and angiogenesis) is accelerated during a 1-week course of ecercise with local administration of SP in an establish Achilles tendinopathy model.

Methods Rabbits were subjected to a protocol of Achilles tendon overuse for 1 week, in conjunction with SP injections in the paratenon. Exercised control animals received NaCl injections or no injections, and unexercised, uninjected controls were also used. Tenocyte number and vascular density, as well as paratendinous inflammation, were evaluated. Immunohistochemistry and in sity hybridisation to detect NK-1R were conducted.

Results There was a significant increase in tenocyte number in the SP-injected and NaCl-injected groups compared with both unexercised and exercised, uninjected controls. Tendon blood vessels increased in number in the SP-injected group compared with unexercised controls, a finding not seen in NaCl-injected controls or in uninjected, exercised animals. Paratendinous inflammation was more pronounced in the SP-injected group than in the NaCl controls. NK-1R was detected in blood vessel walls, nerves, inflammatory cells and tenocytes.

Conclusions SP accelerated the development of tendinosis-like changes in the rabbit. Achilles tendon, which supports theories of a potential role of SP in tendinosis development; a fact of clinical interest since SP effects can be effectively blocked. The angiogenic response to SP injections seems related to parateninitis.

Place, publisher, year, edition, pages
Loughborough: British Assoc. of Sport and Medicine, 2011
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:umu:diva-42293 (URN)10.1136/bjsm.2010.082750 (DOI)
Available from: 2011-04-07 Created: 2011-04-07 Last updated: 2019-02-22Bibliographically approved
Andersson, G., Forsgren, S., Scott, A., Gaida, J. E., Stjernfeldt, J. E., Lorentzon, R., . . . Danielson, P. (2011). Tenocyte hypercellularity and vascular proliferation in a rabbit model of tendinopathy: contralateral effects suggest the involvement of central neuronal mechanisms. British Journal of Sports Medicine, 45(5), 399-406
Open this publication in new window or tab >>Tenocyte hypercellularity and vascular proliferation in a rabbit model of tendinopathy: contralateral effects suggest the involvement of central neuronal mechanisms
Show others...
2011 (English)In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 45, no 5, p. 399-406Article in journal (Refereed) Published
Abstract [en]

Objective To determine whether there are objective findings of tendinosis in a rabbit tendinopathy model on exercised and contralateral (non-exercised) Achilles tendons. Design Four groups of six New Zealand white rabbits per group were used. The animals of one (control) group were not subjected to exercise/stimulation. Interventions Animals were subjected to a protocol of electrical stimulation and passive flexion-extension of the right triceps surae muscle every second day for 1, 3 or 6 weeks. Main Outcome Measures Tenocyte number and vascular density were calculated. Morphological evaluations were also performed as well as in-situ hybridisation for vascular endothelial growth factor (VEGF) messenger RNA. Results There was a significant increase in the tenocyte number after 3 and 6 weeks of exercise, but not after 1 week, in comparison with the control group. This was seen in the Achilles tendons of both legs in experimental animals, including the unexercised limb. The pattern of vascularity showed an increase in the number of tendon blood vessels in rabbits that had exercised for 3 weeks or more, compared with those who had exercised for 1 week or not at all. VEGF-mRNA was detected in the investigated tissue, with the reactions being more clearly detected in the tendon tissue with tendinosis-like changes (6-week rabbits) than in the normal tendon tissue (control rabbits). Conclusions There were bilateral tendinosis-like changes in the Achilles tendons of rabbits in the current model after 3 weeks of training, suggesting that central neuronal mechanisms may be involved and that the contralateral side is not appropriate as a control.

National Category
Cell and Molecular Biology
Research subject
Human Anatomy
Identifiers
urn:nbn:se:umu:diva-35363 (URN)10.1136/bjsm.2009.068122 (DOI)20605910 (PubMedID)
Note

E-pub ahead of print.

Available from: 2010-08-13 Created: 2010-08-13 Last updated: 2018-06-08Bibliographically approved
Bagge, J., Lorentzon, R., Alfredson, H. & Forsgren, S. (2009). Unexpected presence of the neurotrophins NGF and BDNF and the neurotrophin receptor p75 in the tendon cells of the human Achilles tendon. Histology and Histopathology, 24(7), 839-848
Open this publication in new window or tab >>Unexpected presence of the neurotrophins NGF and BDNF and the neurotrophin receptor p75 in the tendon cells of the human Achilles tendon
2009 (English)In: Histology and Histopathology, ISSN 0213-3911, E-ISSN 1699-5848, Vol. 24, no 7, p. 839-848Article in journal (Refereed) Published
Abstract [en]

Neurotrophins are substances that have been shown to be important in growth and remodelling phases in different types of tissue. There is no information concerning the possible occurrences of neurotrophins and their receptors in tendons. In this study, sections of both chronic painful (tendinosis) and pain-free (non-tendinosis) human Achilles tendons were immunohistochemically stained with antibodies against the neurotrophins NGF and BDNF, and their receptors TrkA, TrkB and p75. There were marked immunoreactions for NGF and BDNF in the tendon cells (tenocytes) of both tendinosis and non-tendinosis specimens. The tenocytes were also reactive for the receptor p75, but not for the receptors TrkA and TrkB. In addition, p75 immunoreactions were seen in nerve fascicles and in the walls of arterioles. This is the first study to identify neurotrophins in the tenocytes of human tendon. It is clear from this study that the local cells of tendons are sources of neurotrophins. The neurotrophins may play an important role in the tendon through their interaction with the receptor p75 in the tenocytes. These interactions may regulate tropic modulatory, and apoptotic effects. In conclusion, the observations show a new concept concerning production and function of neurotrophins, namely in the tenocytes of tendons.

Keywords
Achilles tendon, Neurotrophins, Tendinopathy, p75, NGF
National Category
Sport and Fitness Sciences Physiology
Identifiers
urn:nbn:se:umu:diva-24109 (URN)19475530 (PubMedID)
Available from: 2009-06-30 Created: 2009-06-30 Last updated: 2018-06-08Bibliographically approved
Högström, M., Nordström, A., Alfredson, H., Lorentzon, R., Thorsen, K. & Nordström, P. (2007). Current physical activity is related to bone mineral density in males but not in females.. International Journal of Sports Medicine, 28(5), 431-436
Open this publication in new window or tab >>Current physical activity is related to bone mineral density in males but not in females.
Show others...
2007 (English)In: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964, Vol. 28, no 5, p. 431-436Article in journal (Refereed) Published
Keywords
Absorptiometry; Photon, Adult, Body Composition, Bone Density/*physiology, Cohort Studies, Female, Humans, Male, Motor Activity/*physiology, Sex Factors
Identifiers
urn:nbn:se:umu:diva-8331 (URN)10.1055/s-2006-924514 (DOI)17111323 (PubMedID)
Available from: 2008-01-17 Created: 2008-01-17 Last updated: 2018-06-09Bibliographically approved
Brax-Olofsson, L., Svensson, O., Lorentzon, R., Lindström, I. & Alfredson, H. (2007). Periosteal transplantation to the rabbit patella.. Knee Surgery, Sports Traumatology, Arthroscopy, 15(5), 560-563
Open this publication in new window or tab >>Periosteal transplantation to the rabbit patella.
Show others...
2007 (English)In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 15, no 5, p. 560-563Article in journal (Refereed) Published
Abstract [en]

Autologous periosteal transplantation (without chondrocyte cell transplantation) for treating traumatic articular cartilage defects of the patella gives pain relief in uncontrolled clinical studies. To study the whole transplanted area macroscopically and microscopically, animal studies are motivated. In this pilot study, we reproduce the surgical technique for periosteum transplantation on human patella to a rabbit model. A full-thickness cartilage defect of the whole patella was created in eight adult female rabbits. The defect was treated with autologous periosteal transplantation. After surgery, the rabbits were allowed free activity. This is the difference compared to the treatment in humans, where our group uses CPM for 5 days and non-weight-bearing for 12 weeks. After 21 weeks, there was a diffuse synovitis in all transplanted knees, and in five of eight knees there were signs of osteoarthritis in the patello-femoral joint. Histologically, in three animals, small islands of hyaline cartilage surrounded by fibrocartilage were seen in the transplanted area. In the other five animals, fibrocartilage was the predominant tissue. In contrast to previous experimental studies using a rabbit model, we did not achieve hyaline cartilage resurfacing.

Place, publisher, year, edition, pages
Berlin: Springer Internat., 2007
Identifiers
urn:nbn:se:umu:diva-14310 (URN)17072658 (PubMedID)
Available from: 2007-05-28 Created: 2007-05-28 Last updated: 2018-06-09Bibliographically approved
Organisations

Search in DiVA

Show all publications