| 1. |
- Albert, Frederic, et al.
(author)
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Proprioceptive feedback in humans expresses motor invariants during writing.
- 2005
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In: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 164:2, s. 242-9
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Journal article (peer-reviewed)abstract
- Proprioceptive feedback from populations of muscle spindle afferents feeds the brain with information relating to the instantaneous velocity and direction of ongoing movements. In this paper, we investigate whether the invariant relationship between the velocity and curvature of a trajectory, i.e. the two-thirds power law, is reflected in this muscle spindle feedback. Sixty unitary muscle spindle afferents from six ankle muscle groups were recorded using intraneural microelectrodes during imposed "writing-like" movements. The movements had kinematic parameters obeying the two-thirds power law and were imposed so that the tip of the foot followed trajectories forming four different letters and six numbers. The responses of the muscle spindle afferent populations were analysed using the population vector model. The results demonstrate that the neuronal trajectories attained from populations of muscle spindles clearly depict the path and kinematic parameters and express the movement invariants, i.e. the trajectory segmentation into units of action and the two-thirds power law. The central vs peripheral origin of such constraints involved in the motor system is discussed.
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| 2. |
- Albert, Frederic, et al.
(author)
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The Ia afferent feedback of a given movement evokes the illusion of the same movement when returned to the subject via muscle tendon vibration
- 2006
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In: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 172:2, s. 163-174
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Journal article (peer-reviewed)abstract
- The aim of the present study was to further investigate the contribution of primary muscle spindle feedback to proprioception and higher brain functions, such as movement trajectory recognition. For this purpose, complex illusory movements were evoked in subjects by applying patterns of muscle tendon vibration mimicking the natural Ia afferent pattern. Ia afferent messages were previously recorded using microneurographic method from the six main muscle groups acting on the ankle joint during imposed "writing like" movements. The mean Ia afferent pattern was calculated for each muscle group and used as a template to pilot each vibrator. Eleven different vibratory patterns were applied to ten volunteers. Subjects were asked both to copy the perceived illusory movements by hand on a digitizing tablet and to recognize and name the corresponding graphic symbol. The results show that the Ia afferent feedback of a given movement evokes the illusion of the same movement when it is applied to the subject via the appropriate pattern of muscle tendon vibration. The geometry and the kinematic parameters of the imposed and illusory movements are very similar and the so-called "two-thirds power law" is present in the reproduction of the vibration-induced illusory movements. Vibrations within the "natural" frequency range of Ia fibres firing (around 30 Hz) produce clear illusions of movements in all the tested subjects. In addition, increasing the mean frequency of the vibration patterns resulted in a linear increase in the size of the illusory movements. Lastly, the subjects were able to recognize and name the symbols evoked by the vibration-induced primary muscle spindle afferent patterns in 83% of the trials. These findings suggest that the "proprioceptive signature" of a given movement is associated with the corresponding "perceptual signature". The neural mechanisms possibly underlying the sensory to perceptual transformation are discussed in the general framework of "the neuronal population vector model".
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| 3. |
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| 4. |
- Bergenheim, Mikael, et al.
(author)
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Spontaneous bursting neuronal discharges recorded from peripheral nerve in human : injury discharges or not?
- 2004
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In: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 359:1-2, s. 1-4
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Journal article (peer-reviewed)abstract
- This paper deals with a spontaneous, bursting neuronal activity which can not be altered by any stimulation in the periphery or voluntary actions or by cognitive tasks. An initial description of such units led to the conclusion that this activity was generated ectopically at the site of a previous or present impalement of a nerve fibre. The aim of the current study was to record a larger number of these units by using microneurography, in order to characterise their firing properties and particularly, see if any subtypes of units could be identified. In conclusion, this paper suggests that some of these discharges could be related to an injury of the nerve fibre, however most of them could not. Some hypothesis regarding the nature of these bursting activities are suggested.
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| 5. |
- Bjoreland, Anders, et al.
(author)
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Liquid ionization chamber calibrated gel dosimetry in conformal stereotactic radiotherapy of brain lesions
- 2008
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In: Acta Oncologica. - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 47:6, s. 1099-1109
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Journal article (peer-reviewed)abstract
- Hypofractionated conformal stereotactic radiotherapy (HCSRT) is an established method of treating brain lesions such as arteriovenous malformations (AVMs) and brain metastases. The aim of this study was to investigate the reliability of treatment plans in the terms of dose distribution and absorbed dose for HCSRT. Methods and materials. Treatment plans for three different clinical intracerebral targets, AVMs, were transferred to a CT study of a spherical water filled phantom simulating the human head and recalculated for the phantom geometry using a standard treatment planning system utilizing a pencil beam algorithm for dose calculation. The calculated absorbed dose, relative three dimensional (3D) dose distribution and dose conformity were investigated using gel dosimetry normalized to liquid ionization chamber (LIC) measurements. Results. The measured absorbed dose to the dose reference point was found to be within 2% of the calculated dose for all three targets. The measured dose distribution was found to be within 3% and 2 mm of the calculated dose for more than 93% of all points in the target volume for all three targets. Conclusions. The results show that the investigated standard treatment planning system can correctly predict the absorbed dose and dose distribution in different types of intracerebral targets and that the treatment can be delivered according to the plan.
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| 6. |
- Björkblom, Benny, et al.
(author)
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Metabolic response patterns in brain microdialysis fluids and serum during interstitial cisplatin treatment of high-grade glioma
- 2020
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In: British Journal of Cancer. - : Nature Publishing Group. - 0007-0920 .- 1532-1827. ; 122:2, s. 221-232
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Journal article (peer-reviewed)abstract
- BACKGROUND: High-grade gliomas are associated with poor prognosis. Tumour heterogeneity and invasiveness create challenges for effective treatment and use of systemically administrated drugs. Furthermore, lack of functional predictive response-assays based on drug efficacy complicates evaluation of early treatment responses.METHODS: We used microdialysis to deliver cisplatin into the tumour and to monitor levels of metabolic compounds present in the tumour and non-malignant brain tissue adjacent to tumour, before and during treatment. In parallel, we collected serum samples and used multivariate statistics to analyse the metabolic effects.RESULTS: We found distinct metabolic patterns in the extracellular fluids from tumour compared to non-malignant brain tissue, including high concentrations of a wide range of amino acids, amino acid derivatives and reduced levels of monosaccharides and purine nucleosides. We found that locoregional cisplatin delivery had a strong metabolic effect at the tumour site, resulting in substantial release of glutamic acid, phosphate, and spermidine and a reduction of cysteine levels. In addition, patients with long-time survival displayed different treatment response patterns in both tumour and serum. Longer survival was associated with low tumour levels of lactic acid, glyceric acid, ketoses, creatinine and cysteine. Patients with longer survival displayed lower serum levels of ketohexoses, fatty acid methyl esters, glycerol-3-phosphate and alpha-tocopherol, while elevated phosphate levels were seen in both tumour and serum during treatment.CONCLUSION: We highlight distinct metabolic patterns associated with high-grade tumour metabolism, and responses to cytotoxic cisplatin treatment.
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| 7. |
- Eriksson, Maria, et al.
(author)
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Improved treatment of glioblastoma : changes in survival over two decades at a single regional Centre
- 2019
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In: Acta Oncologica. - : Taylor & Francis Group. - 0284-186X .- 1651-226X. ; 58:3, s. 334-341
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Journal article (peer-reviewed)abstract
- Background: Glioblastoma (GBM) is an aggressive brain tumor with a short overall survival (OS) in general. The treatment of GBM has evolved over the last decades and is today multimodal including surgical resection followed by radiochemotherapy and adjuvant chemotherapy for patients in good performance status. The aim of this study was to evaluate the development of treatment and the outcome for GBM patients at a single regional center.Patients and methods: Survival was studied for 571 patients in our region diagnosed with GBM between 1995 and 2015. Samples from 244 patients out of those treated 2005-2015 have been included in a tissue/blood bank and a clinical database has been set up with basic patient characteristics and details on surgery and non-surgical treatment.Results: The median OS for all patients from 1995 to 2015 was 9.3 months. There was a stepwise improvement from 6.9 to 10.3 months for patients diagnosed 1995-1996 and 2010-2015, respectively (p<.05). The 2-year survival for the same time periods improved from 7% to 18% (p<.01). After introduction of postoperative radiochemotherapy for patients in good performance status in 2005 an increased OS was noted and following implementation of intraoperative 5-aminolevulinic acid the number of tumor resection 95% did increase from 33% to 54% (p<.001). Positive prognostic factors for survival were young age, good performance status, absence of inflammatory disease, absence of diabetes or metabolic disease, tumor resection 95%, and completion of postoperative radiochemotherapy.Discussion: The results of this study are consistent with earlier results regarding survival and prognostic factors and confirm results from randomized controlled trials in a clinical setting. Despite the improvements made, the prognosis is still dismal and the need for further research on GBM treatment is great.
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| 8. |
- Eriksson, Maria, et al.
(author)
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Treatment of Glioblastoma : Improvements over two decades at a single centre
- 2018
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In: Neuro-Oncology. - : Oxford University Press. - 1522-8517 .- 1523-5866. ; 20, s. 236-236
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Journal article (other academic/artistic)abstract
- INTRODUCTION: Glioblastoma (GBM) is a rapidly progressing tumour with a short overall survival. The treatment of GBM has evolved over the last decades and is today multimodal including surgery with maximal tumour resection followed by radiotherapy and chemotherapy for patients in good performance status. The aim of this study was to evaluate the development of treatment and the outcome for GBM patients at a single centre.PATIENTS AND METHODS: 244 patients treated for GBM 2005 - 2015 has been included in a tissue bank with tumour tissue and/or blood samples. A clinical database has been set up with basic patient characteristics and details on surgery and non-surgical treatment. Survival was also studied for all 571 patients in our region diagnosed with GBM between 1995 and 2015.RESULTS: The overall median survival for all patients from 1995 to 2015 was 9.3 months. There was a stepwise improvement from 6.9 to 10.3 months for patients diagnosed 1995–1996 and 2010–2015, respectively (p<0.05). The two-year survival for the same time periods improved from 7.4% to 17.8% (p<0.01). After the introduction of postoperative radiochemotherapy for patients in good performance status in 2005 an increased survival was noted. The implementation of intraoperative 5-aminolevulinic acid did, in patients that underwent tumour resection, increase the number of total tumour resections (≥95%) from 32.6% to 54.1% (p<0.001). Positive prognostic factors were young age, good performance status, absence of diabetes or metabolic disease, total tumour resection and completion of postoperative radiochemotherapy.CONCLUSIONS: The results of this study are in line with earlier results regarding survival and prognostic factors. Despite the improvements made, the prognosis is still dismal and the need for further research on GBM treatment is great.
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| 9. |
- J:son Lönn, Eva, 1960-
(author)
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Jobb(iga) nyheter : om dagstidningars bevakning av arbetsmiljöfrågor
- 2005
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Doctoral thesis (other academic/artistic)abstract
- In the beginning of this millennium the increasing level of work related illness was de-scribed, in the public debate, as one of the most serious and costly social problems of our times. An important question in the present study is whether or not the newspapers contributed to make their readers, the politicians and other social actors aware of this vast and growing problem.Thus, the main purpose was to find out the extent of the news media coverage on occupational health/ill-health in Swedish newspapers in the end of the 1990s, and the ways in which the topic was framed. Furthermore the intent was to produce a better and deeper understanding of the factors influencing the coverage.Theoretically the study draws on framing theory. Framing here refers to the process through which complex issues are reduced to journalistically manageable dimensions in the construction of news stories, resulting in a text, a news story that presents and high-lights some aspects and perspectives of the perceived reality but not others.A combination of research methods was used - A content and frame analysis of six months of occupational health coverage in seven newspapers; an interview study with journalists and their scientific sources about the news production; a one week’s news-room study aimed at observing the everyday production of news; and finally, a short email survey directed to the editorial staff at the examined news papers, with the purpose to get some indication on how the coverage of occupational health was organised and prioritized at the different newspapers.In the empirical analysis the newspapers´ picturing of occupational health/ill-health was compared with picture emerging from official statistics on occupational sickness and injury. In many respects a deviation was found between the two. Furthermore, simi-larities and differences in content between different newspapers, between different news sections and between news stories written by journalists of different sex, were examined.A key finding is that the Swedish newspapers did not draw their readers’ attention to the extensive and growing problem at the places of work. A majority of the stories related to occupational health/ill-health were episodic, and treated the issues as isolated and random events rather than predictable and preventable problems, although there were also more thematic articles written during special circumstances. The results indicate that a primary cause of the topics low priority in the newspapers was that the coverage of occupational health/ill-health had not been integrated into the journalistic routines.
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| 10. |
- Johansson, Mikael, et al.
(author)
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Tumor blood flow and the cytotoxic effects of estramustine and its constituents in a rat glioma model
- 1997
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In: Neurosurgery. - : Oxford University Press. - 0148-396X .- 1524-4040. ; 41:1, s. 237-244
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Estramustine (EaM) is a conjugate of nor-nitrogen mustard (NNM) and 17 beta-estradiol (E2) that has cytotoxic and radiosensitizing effects on experimental malignant glioma. Its mechanism of action is only partly understood. To further investigate the mechanism in vivo, the effects on tumor blood flow (TBF) and tumor growth were analyzed.METHODS: TBF was measured by radioactive microspheres, and tumor growth was measured by weight. Apoptosis was evaluated by in situ end labeling and gel electrophoresis. The effects of the constituents NNM and E2 were also evaluated.RESULTS: EaM increased TBF to 153.8 ml/100 g/min after 3 days and to 153.9 ml/100 g/min after 10 days of treatment, compared with 94.0 ml/100 g/min in untreated controls. Cerebral blood flow did not change after EaM treatment. NNM increased TBF but also showed a tendency to increase cerebral blood flow. E2 increased TBF, whereas cerebral blood flow was unchanged. EaM resulted in a rapid reduction in tumor weight from 230 mg in untreated animals to 146 mg after 3 days of treatment. EaM induced an early transient fragmentation of deoxyribonucleic acid in glioma but not in the normal brain. Neither NNM nor E2 affected tumor weight.CONCLUSION: EaM increases TBF in the BT4C rat glioma model with a concomitant rapid antitumoral effect. The increase in TBF could partially be induced by an estrogen-like action of EaM, but the rapid cytotoxic effect of the drug is obviously attributed to the intact EaM compound. This cytotoxic effect might be attributable to the induction of programmed cell death.
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