Biomedical subjects

Magnus Karlsson

Publications and source records attributed to Magnus Karlsson.

11 recordsLinked to original sources

PubMed2004

Diffusion-weighted MRI of soft tissue tumours.

The purpose of this study was to evaluate the clinical utility of a multi-shot spin-echo echo-planar (SE-EPI) diffusion-weighted sequence in the diagnostic work-up of soft tissue tumours. There were 29 patients, 16 with a benign lesion and 13 with a sarcoma. Four of the sarcomas were examined both before and after radiation therapy. Diffusion-weighted imaging was performed with a multi-shot SE-EPI sequence. The b values were 0 and 600 s/mm(2). Phase navigation and pulse trigging were applied. The apparent diffusion constant (ADC) value of a large region of interest (ROI) representing the lesion was measured and compared to diagnosis and treatment. The ADC values of the benign lesions (mean 1.8 x 10(-3) mm(2)/s) overlapped with non-treated sarcomas (mean 1.7 x 10(-3) mm(2)/s). The ADC value increased in all radiated sarcomas. A multi-shot SE-EPI diffusion imaging sequence of less than 2-min duration is technically feasible in soft tissue tumours of the extremities and the trunk. The ADC values of benign soft tissue tumours and sarcomas overlapped and could not be used to differentiate between the bulk of benign and malignant tumours. However, the increase in ADC values of soft tissue sarcomas after radiotherapy warrants further studies of diffusion imaging for evaluating therapy response.

Adult↗

PubMed2004

Peripheral nerve diffusion tensor imaging.

We examined if MR diffusion tensor imaging with fiber tracking could be performed on the sciatic nerve. In 3 healthy volunteers the proximal thigh was examined on a 1.5-Tesla MR-scanner with a 2-channel phased-array coil. Though inherently susceptible to motion, field inhomogeneities, and fast T(2)-relaxation of the diffusion imaging technique, the sciatic nerve could be detected and correlated to T(2)-weighted images in all 3 subjects. Further investigations need to be done to improve the signal-to-noise ratio and to see if smaller peripheral nerves than the sciatic nerve can be detected.

Diffusion Magnetic Resonance Imaging↗

PubMed2004

Activities of daily living decrease similarly in hospital-treated patients with a hip fracture or a vertebral fracture: a one-year prospective study in 151 patients.

AIMS: A hip fracture is commonly regarded as the most devastating fragility fracture, as regards both morbidity and mortality, while a vertebral fracture is usually regarded as having lower general morbidity. The purpose of this study was to investigate whether hospitalized patients with a hip or a vertebral fracture experience similar functional deterioration following the fracture as regards activity of daily living (ADL) and experienced quality of life (QOL). METHODS: Eighty-seven women and 22 men, mean age 81 (range 66-96), with a hip fracture and 34 women and 8 men, mean age 81 (range 68-92), with a vertebral fracture were followed up for 12 months. ADL before fracture and at 4 and 12 months after the fracture were evaluated as well as QOL at 4 and 12 months after the fracture, by questionnaires. RESULTS: A hip and a vertebral fracture in community dwellers within the same age range confers a similar decrease in ADL during the four months following the fracture. No restoration was seen in ADL or total QOL during the year following the fracture. Patients with a vertebral fracture had a lower QOL than patients with a hip fracture 4 and 12 months after the fracture. CONCLUSION: The need for external community assistance for patients with a vertebral fracture that forces them to have hospital treatment may be similar to the need following a hip fracture.

Activities of Daily Living↗

PubMed2004

Body composition profiles derived from dual-energy X-ray absorptiometry, total body scan, and mortality.

Little has been reported on the association of derived body composition data and cardiovascular mortality. The authors defined body composition profiles based on one- and two-variable measures from dual-energy x-ray absorptiometry (DXA) total body scans. Scan results are labeled "apple" if Z score for percent of total fat in trunk is >0 and "pear" if Z score for height-corrected limb fat is > or = 0. The fat measures were combined to define four body composition profiles: "pickle," "avocado," "mango," and "barrel." A third axis, the Z score of height-corrected limb lean tissue, is an index of skeletal muscle mass and was used to label subjects as "hard" or "soft." Subjects (n=324) who were in good health from Malmö, Sweden, underwent body composition analysis using DXA and were followed for 10 years. The distribution of body composition profiles was similar for both genders and across age groups. Among subjects aged 50-74 years at baseline (n=116), there were 21 deaths. Barrel had the highest mortality rate: 13/39 (33.3%) mortality for barrels, compared with 8/77 (10.4%) mortality for non-barrels; mortality odds ratio, 3.2; 95% confidence interval, 1.45-7.08. The increased mortality was principally attributable to cardiovascular cause-related deaths. Soft (sarcopenia) was also associated with increased mortality (25.9%; p=0.05), but not cardiovascular cause-related deaths, whereas the total mortality among apples was not significantly increased but cardiovascular cause-related deaths were predominant (75%; p=0.02). The authors propose that DXA-body composition profiles can identify increased mortality risk of magnitude similar to major cardiovascular risk factors and may prove useful in health assessment.

Absorptiometry, Photon↗

PubMed2004

Has exercise an antifracture efficacy in women?

Exercise in girls during growth seems to confer a high peak bone mineral density (BMD). Exercise in adulthood, in the peri- and postmenopausal period, and in old age prevents bone loss or increases BMD with a magnitude of minor biological significance. However, these changes must be regarded as beneficial compared to the age-related bone loss, which inevitably will occur if no interventions are implemented. Prospective intervention studies also suggest that exercise improves muscle strength, coordination and balance, even in elderly women, all of which are improvements with a potential of reducing the number of falls. A randomised, controlled, prospective, blinded study (the only study design that tests a hypothesis) of exercise with fracture as end point is extremely difficult to conduct, due to the large sample sizes needed. At present, no such studies exist. Retrospective and prospective observational and case-control studies suggest that physical activity in women is associated with reduced fracture risk. This may be correct, but we must never forget that a consistently replicated sampling bias may produce the same outcome. The Achilles heel of exercise is the reduction or the cessation of physical activity, which commonly occurs among middle-aged women when family and work demands reduce the time available for exercise. A higher BMD or improvement in muscle size and muscle strength achieved by exercise during adolescence seems to be eroded on retirement, leaving virtually no remaining benefits in old age, the period when fragility fractures begin to be a problem of increasing magnitude. However, recreational activities seem to maintain some of the musculo-skeletal benefits, but to date we do not know the level of activity needed to retain these benefits. Dose-response relationships need to be quantified, as also the effects on bone size, shape and architecture. Another essential question that we must address is how many fewer fractures will be the result of a community-based exercise campaign. Will efforts by the community to encourage a higher level of physical exercise, with the aim of reducing bone fractures, be cost-effective? The higher level of proof, suggesting that exercise does reduce fragility fractures and thus reduces the total cost for the society, must come from well-designed and well-executed, prospective, randomised, controlled trials. The responsibility of executing these studies lies in the hands of both researchers and the community.

Accidental Falls↗

PubMed2004

Uncomplicated Mason type-II and III fractures of the radial head and neck in adults. A long-term follow-up study.

BACKGROUND: The purpose of this study was to evaluate the incidence and the long-term results of closed uncomplicated Mason type-II and III fractures in a defined population of adults. METHODS: Seventy women and thirty men who were a mean of forty-seven years old when they sustained a fracture of the radial head or neck (a Mason type-II fracture in seventy-six patients and a Mason type-III fracture in twenty-four) were reexamined after a mean of nineteen years. Radiographic signs of degenerative changes of the elbow were recorded. The fracture had been treated with an elastic bandage or a collar and cuff sling with mobilization for forty-four individuals, with cast immobilization for thirty-four, with resection of the radial head in nineteen, with open reduction of the radial head in two, and with a collateral ligament repair in one. Secondary excision of the radial head was performed because of residual pain in nine patients, and a neurolysis of the ulnar nerve was performed in one patient. RESULTS: Seventy-seven individuals had no symptoms in the injured elbow at the time of follow-up, twenty-one had occasional pain, and two had daily pain. The injured elbows had a slight flexion deficit compared with the uninjured elbows (mean and standard deviation, 138 degrees +/- 8 degrees compared with 140 degrees +/- 7 degrees ) as well as a small extension deficit (mean and standard deviation, -4 degrees +/- 8 degrees compared with -1 degrees +/- 6 degrees ) (p < 0.001 for both). The prevalence of degenerative changes was higher in the injured elbows than in the uninjured ones (76% compared with 16%, p < 0.001). CONCLUSIONS: The results following uncomplicated Mason type-II and III fractures are predominantly favorable. A secondary radial head resection is usually effective for patients with an unfavorable outcome (predominantly long-standing pain). LEVELS OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Activities of Daily Living↗

PubMed2003

Expressed sequences from the basidiomycetous tree pathogen Heterobasidion annosum during early infection of scots pine.

The pattern of gene expression of the basidiomycete Heterobasidion annosum, causal agent of the root rot of conifers, was analysed during its interaction with pine roots. A complementary DNA (cDNA) library was constructed from total RNA extracted from H. annosum mycelia challenged with Scots pine seedling roots for 6 and 72h. Single pass sequencing of 1148 randomly selected cDNA clones resulted in 923 expressed sequence tags (ESTs). Contig analysis and sequence comparisons identified 318 unigene sequences, of which 62 were repeatedly sampled. A putative cellular function was assigned to 223 contigs (70%) that showed a moderate to high homology to protein sequences from public databases. Variations in expression levels during the infection process were monitored on a set of 96 unigenes by reverse northern using dot hybridisation. Seven unigenes (7%) were shown to be either up (4) or down (3) regulated during interaction of the fungus with pine roots. Fungal genes differentially expressed during contact with roots include genes encoding mitochondrial proteins, a cytochrome P450 and a vacuolar ATP synthase.

Basidiomycota↗

PubMed2002

[Exercise increases bone mass in children but only insignificantly in adults].

Data supporting the notion that exercise during growth built a stronger skeleton is compelling. Exercise during growth, especially during the pre-pubertal years, increases bone mineral density (BMD) and perhaps also bone size, each independently conferring bone strength. In adulthood, exercise at best halts bone loss or increases BMD by a few percentage points, an increase of questionable biological significance. High lifelong work load and high leisure time activity level are associated with high BMD. The Achilles heel of exercise is its cessation. Most BMD benefits achieved by exercise during growth are lost with cessation of exercise. Exercise at a lower level, after a period of high intense activity, may retain residual BMD benefits into old age. A reduced rate of fragility fractures in the population could perhaps be achieved by promoting a physically active lifestyle with lifelong high activity level during work and leisure time, leading to high BMD and fewer fractures.

Adolescent↗

PubMed2002

[Exercise increases muscle strength and probably prevents hip fractures].

No hypothesis-testing studies (blinded, randomized, controlled, prospective) with fracture as endpoint have been published so far. Instead we have to rely on observational cohort and case-control studies, from which available data imply that physical activity reduces the risk of hip fracture in women and perhaps also in men. This could be the case, but repeated sampling bias could present the same outcome. Whether or not exercise reduces the number of vertebral fractures and other fragility fractures is less often evaluated. Fracture rate seems not to be reduced with cessation of exercise. The evidence that exercise modifies the risk of falling is compelling. Exercise is associated with improved muscle strength, coordination and balance. Exercise increases muscle strength even in octogenarians by 20-200 per cent, but these benefits are lost if activity is reduced. Exercise reduces the risk of falling and perhaps also the number of falls. Whether or not the number of injurious falls is reduced by exercise is even more hotly debated.

Accidental Falls↗

PubMed2002

Is exercise of value in the prevention of fragility fractures in men?

Exercise during growth seems to build a stronger skeleton resulting in a high peak bone mineral density (BMD) in men. Exercise during adulthood produces benefits in BMD or prevents bone loss, but the changes are of minor biological significance as regards fracture reduction. However, prospective intervention studies suggest exercise to improve muscle strength, co-ordination and balance, even in octogenarians--all traits possible to reduce the number of falls. It is virtually impossible to undertake a randomized blinded study of exercise with fracture as end point due to the large cohorts needed. Retrospective and prospective observational and case control studies suggest activity to be associated with reduced fracture risk. This may be correct, but consistently replicated sampling bias may produce the same observation. The Achilles heel of exercise is the cessation of physical activity. Biologically important benefits in BMD or improvement in muscle size and strength achieved by exercise during growth and young adulthood seem to be eroded in retirement, leaving virtually no remaining benefits in old age, the period when fragility fractures exponentially rise. On the contrary, continued exercise on a lower level may maintain some of the musculoskeletal benefit, but dose-response relationships need to quantified, as do the effects of exercise on bone size, shape, architecture and frequency of injurious falls. Absence of evidence is not evidence of absence of effect, but if we recommend exercise then should this be to children, adults, elderly men or men with fractures? What type of exercise? For how long? How many fewer fractures will result in the community from a community based exercise campaign like the anti-tobacco campaign? The higher level of proof, suggesting exercise to reduce spine and hip fractures must come from well designed and executed prospective randomized studies. Blinded studies obviously cannot be done but open trials can, and should be undertaken.

Accidental Falls↗

PubMed2002

Does exercise reduce the burden of fractures? A review.

The null hypothesis that exercise has no effect on fracture rates in old age cannot be rejected on the basis of any published, randomized, prospective data. The view that exercise reduces the number of fractures is based on prospective and retrospective, observational cohort studies and case-control studies, all hypothesis-generating, not hypothesis-testing. Consistently replicated sampling bias may confirm the finding when evaluating other than randomized prospective studies. Better health, better muscle function, more muscle mass, better coordination may lead to exercise. The causal relationship could be between better health and exercise and better health and fewer fractures, not exercise and fewer fractures. The hypothesis should be tested in prospective, randomized studies evaluating hip, spine and other fragility fractures separately. Blinded studies assessing the effects of exercise can obviously not be done, but open trials can and should be undertaken to increase the level of evidence within the evidence-based system. There are firm data supporting the view that exercise during growth builds a stronger skeleton. Exercise during growth seems to result in high peak BMD and high muscle strength. However, the Achilles heel of exercise is its cessation. Are the skeletal and muscular benefits attained during growth retained after the cessation of exercise and can any residual benefits be found in old age, the period when fragility fractures rise exponentially? Does exercise during adulthood produce any biologically important reduction in surrogate end-points for fractures other than BMD, since BMD can be influenced only marginally by exercise after completion of growth? Recommendations for exercise should be based on evidence, not on opinion. Can continued recreational exercise maintain some of the benefits in BMD and muscle function achieved in youth? What level of recreational exercise is needed to retain these benefits, if not fully, then at least to some extent? Dose-response relationships should be quantified. Furthermore, the effect of exercise on independent, surrogate end-points for fractures, such as bone size, shape, architecture, muscle function, fall frequency and frequency of injurious falls during defined periods in the life cycle must be determined. Absence of evidence is not evidence of absence of effect, but if we recommend exercise then should this be to children, adults, elderly, men and women with fractures, all persons? What type of exercise? For how long? Lifelong? If exercise could be implemented for most persons in society, would this reduce the number of fractures? Would the increased costs associated with the efforts to increase the activity level be lower than the reduced costs associated with any reduction in fractures? Our inability to answer these questions must be acknowledged before recommendations are made at the community level.

Accidental Falls↗