| 41. |
- Latini, Francesco, M.D. 1982-
(författare)
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Significance of white matter anatomy in interpreting features and behaviour of low-grade gliomas and implications for surgical treatment
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diffuse gliomas are extremely heterogeneous tumours characterized by slow growth but extensive infiltration. Their kinetic features reflect the complex interaction over time with the surrounding brain, influencing treatment planning and outcome. Indeed, resection of diffuse gliomas present a surgical challenge due to their invasiveness and the preferential location in eloquent regions. White matter bundles are the main eloquent limit to surgical resection, but this anatomical-functional information cannot be predicted preoperatively on the individual level. The incomplete description of the human brain connectome, the complex application of pathological/lesion model to the brain connectomic organization, and the underestimated role of white matter anatomy in radiological classification systems are among the major limitations for the comprehension of the glioma/white matter interaction. The overall aim of this thesis was to explore a new approach and new techniques to study the glioma/white matter interaction. A combination of white matter dissection and diffusion tensor tractography (DTT) was used to describe the connectomic organization of two major temporo-occipital connections, the inferior and the middle longitudinal fasciculus. This information was applied to patients with diffuse gliomas, demonstrating how white matter analysis was important to decode patient specific cognitive and language impairment. A new classification system for diffuse gliomas, the Brain-Grid, was created, merging local radiological anatomy with a DTT atlas for infiltration analysis. This standardized radiological tool provided information on subcortical extension (tumour invasiveness), speed, and preferential direction of glioma progression. Applied to a larger cohort of patients, differences were detected between diffuse gliomas subtypes. Tumour invasiveness and the preferential location, type, and extent of white matter involvement differed, impacting overall survival. Regional differences in white matter infiltration were detected among five major white matter bundles, and possible favourable morphological and diffusion features were investigated with transmission electron microscopy and DTT. Fibre diameter, myelin thickness, and the organization of the white matter fibres were different in regions with high infiltration frequency, providing a possible link to the preferential location of diffuse gliomas. Finally, the white matter connectivity, tumour-induced neuroplasticity, clinical and demographic information, preoperative assessment (neuropsychological and language evaluation) were compared with intraoperative findings during awake surgery. Neuropsychological impairment was associated with more invasive tumours and a higher risk of the intraoperative finding of eloquent tumour. The pattern of early cortical neuroplasticity seemed exhausted at the time of diagnosis, with age as a factor predicting the neuroplasticity potential. The combined use of these new techniques revealed new insights into the glioma/white matter interaction. The results provided in this thesis, describe a new way to structure the multidisciplinary perioperative management of these patients. This new information may improve the functional outcome at the individual level, resulting in prolonged survival for adults with diffuse gliomas.
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| 42. |
- Maeder, Philippe P, et al.
(författare)
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Colloid cysts of the third ventricle: correlation of MR and CT findings with histology and chemical analysis
- 1990
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Ingår i: AJNR. - 1936-959X. ; 155:1, s. 135-141
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Tidskriftsartikel (refereegranskat)abstract
- Eight patients with colloid cysts of the third ventricle were examined with CT and MR. In six, surgical resection was performed and the material was subjected to histologic evaluation; the concentrations of trace elements were determined by particle-induced X-ray emission. Stereotaxic aspiration was performed in two. The investigation showed that colloid cysts are often iso- or hypodense relative to brain on CT (5/8), but sometimes have a center of increased density. Increased density did not correlate with increased concentration of calcium or other metals but did not correlate with high cholesterol content. Colloid cysts appear more heterogeneous on MR (6/8) than on CT (3/8), despite a homogeneous appearance at histology. High signal on short TR/TE sequences is correlated with a high cholesterol content. A marked shortening of the T2 relaxation time is often noticed in the central part of the cyst. Analysis of trace elements showed that this phenomenon is not related to the presence of metals with paramagnetic effects. Our analysis of the contents of colloid cysts does not support the theory that differing metallic concentrations are responsible for differences in MR signal intensity or CT density. We did find that increased CT density and high MR signal correlated with high cholesterol content.
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| 43. |
- Mårtensson, Linda, et al.
(författare)
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A nonsurgical technique for blood access in extracorporeal affinity adsorption of antibodies in rats.
- 2007
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Ingår i: Artificial Organs. - : Wiley. - 0160-564X .- 1525-1594. ; 31:4, s. 312-316
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies for targeting cytotoxic conjugates to tumor cells are currently being evaluated together with extracorporeal affinity adsorption. The aim of the adsorption was to reduce undesired side effects in normal organs and to increase the tumor-to-normal tissue ratios. This technique is also applicable to several other therapeutic areas such as immune-mediated disorders, that is, autoimmunity, allergy, and transplantation rejection. We describe an improved technique for extracorporeal affinity adsorption of radiolabeled biotinylated antibodies in rats. Blood access is established through the tail artery and tail vein, without surgical insertion of permanent catheters. This technique is simple, does not require surgery, and causes only minimal stress to the animals. In addition, experiments can be carried out on several animals simultaneously. This new technique is of considerable benefit for studying extracorporeal affinity adsorption in rats, as experiments can be carried out with negligible anatomical and physiological interventions, compared to previously used techniques.
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| 44. |
- Möller, Karin, 1962, et al.
(författare)
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Avanta versus Swanson silicone implants in the MCP joint--a prospective, randomized comparison of 30 patients followed for 2 years
- 2005
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Ingår i: J Hand Surg [Br]. - : SAGE Publications. - 0266-7681. ; 30:1, s. 8-13
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Tidskriftsartikel (refereegranskat)abstract
- The results of Swanson and Avanta metacarpophalangeal joint arthroplasties in rheumatoid patients were compared in a prospective, randomized study of 30 patients (120 implants). At 2-year follow-up, grip strength was measured, hand function was assessed with the Sollerman test and the subjective outcome was determined with visual analogue scores. With both implants ulnar deviation and flexion deformities decreased, and there was no difference between the groups. The increase in range of motion was 7 degrees greater with Avanta implants than with Swanson implants. Grip strength and hand function were unaltered but the visual analogue scales showed decreased pain levels and subjective improvements in hand function, grip strength and cosmesis. Twenty-four of 30 patients were satisfied. Fracture of the silicone spacer occurred with 12 Avanta (20%) and eight Swanson implants (13%), with a higher fracture frequency in men.
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| 45. |
- Nilsson, Daniel, 1973, et al.
(författare)
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[New possibilitys in surgery for brain tumors with intraoperative MRI]. : Intraoperativ MRT ger nya möjligheter för neurokirurgi.
- 2019
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Ingår i: Läkartidningen. - 1652-7518. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- In surgery for brain tumors, the main challenge is to resect the tumor completely without causing injury to surrounding structures. Intraoperative MRI can provide updated information on remaining tumor and the relationship to critical brain structures. We report our initial experiences from an intraoperative 3 T MRI suite from a surgical, radiological and anesthesiological perspective. The technique has been useful in treating pediatric brain tumor patients, pituitary tumors, low-grade gliomas and epilepsy surgery patients. Image quality has been comparable to conventional diagnostic MRI and there have been no adverse events from the technique. Team-based training and simulation are key factors to manage this complex technical environment and make intraoperative MRI into a routine procedure.
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| 46. |
- Nittby, Henrietta, et al.
(författare)
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Cognitive impairment in rats after long-term exposure to GSM-900 mobile phone radiation
- 2008
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Ingår i: Bioelectromagnetics. - : Wiley. - 0197-8462 .- 1521-186X. ; 29:3, s. 219-232
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Tidskriftsartikel (refereegranskat)abstract
- Considering the frequent use of mobile phones, we have directed attention to possible implications on cognitive functions. In this study we investigated in a rat model the long-term effects of protracted exposure to Global System for Mobile Communication-900 MHz (GSM-900) radiation. Out of a total of 56 rats, 32 were exposed for 2 h each week for 55 weeks to radio-frequency electromagnetic radiation at different SAR levels (0.6 and 60 mW/kg at the initiation of the experimental period) emitted by a (GSM-900) test phone. Sixteen animals were sham exposed and eight animals were cage controls, which never left the animal house. After this protracted exposure, GSM-900 exposed rats were compared to sham exposed controls. Effects on exploratory behaviour were evaluated in the open-field test, in which no difference was seen. Effects on cognitive functions were evaluated in the episodic-like memory test. In our study, GSM exposed rats had impaired memory for objects and their temporal order of presentation, compared to sham exposed controls (P = 0.02). Detecting the place in which an object was presented was not affected by GSM exposure. Our results suggest significantly reduced memory functions in rats after GSM microwave exposure (P = 0.02).
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| 47. |
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| 48. |
- Salford, Leif, et al.
(författare)
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The mammalian brain in the electromagnetic fields designed by man with special reference to blood-brain barrier function, neuronal damage and possible physical mechanisms
- 2008
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Ingår i: PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT. - 0375-9687. ; :173, s. 283-309
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Konferensbidrag (refereegranskat)abstract
- Life oil earth was formed during billions of years, exposed to, and shaped by the original physical forces such as gravitation, cosmic irradiation, atmospheric electric fields and the terrestrial magnetism. The Schumann resonances at 7.4 Hz are all example of oscillations possibly important for life.(1)) The existing organisms are created to function in harmony with these forces. However, in the late 19th century mankind introduced the use of electricity, in the early 20th century long-wave radio and in the 1940-ies short-wave radio. High frequency RF was introduced in the 50-ies as FM and television and during the very last decades, microwaves of the modern communication society spread around the world. Today, however, one third of the world's population is owner of the microwave-producing mobile phones and an even larger number is exposed to the cordless RF emitting systems. To what; extent are all living organisms affected by these, almost everywhere present radio frequency fields? And what will be the effects of many years of continuing exposure? Since 1989 Our group has studied the effects upon the mammalian blood-brain barrier (BBB) in rats by non-thermal radio frequency electromagnetic fields (RF-EMF). These have been shown to cause significantly increased leak-age of the rats' own blood albumin through the BBB of exposed rats, at energy levels of 1W/kg and below, as compared to non-exposed animals in a total series of about two thousand animals.(2)-6)) One remarkable observation is the fact that the lowest energy levels, with whole-body average power densities below 10mW/kg, give rise to the most pronounced albumin leakage. If mobile communication, even at extremely low energy levels, causes the users' own albumin to leak out through the BBB, also other unwanted and toxic molecules in the blood, may leak into the brain tissue and concentrate in and damage the neurons and glial cells of the brain. In later studies we have shown that a 2-h exposure to GSM 915 MHz, at non-thermal SAB-values of 0.2, 2 and 200 mW/kg, gives rise to significant neuronal damage, seen not only 50 days after the exposure 7) but also after 28 days but not after 14 days. Albumin extravasations and uptake into neurons was enhanced after 14 clays, but not after 28.(8)) in our continued research, also the non-thermal effects oil tissue structure and memory function of long-term exposure for 13 months are studied.(9)) We have also performed microarray analysis of brains from rats exposed to short term GSM both at 1,800 MHz and at 900MHz and have found significant effects upon gene expression of membrane associated genes as compared to control animals.(10),11)) Most of our findings support that living organisms are affected by the non-thermal radio frequency fields. Some other Studies agree while others find no effects. The mechanisms by which the EMFs may alter BBB permeability are not Well Understood. At low field strengths, the effects on body temperature are negligible and thus heating effects are not involved. A change in the physicochemical characteristics of membranes has been suggested as a cause.(12)) We have performed experiments to verify a quantum mechanical model for interaction with protein-bound ions. Our results show that controlled frequency and amplitude of ELF EM fields upon spinach plasma vesicles can steer transport over the membrane.(13)) This may be a first proof of a resonance phenomenon where appropriate levels of frequency and amplitude in the right combination have the potency to communicate with the biology of membranes and transport systems. Our study has prompted Lis to elaborate on magnetic resonance models; the Ion Cyclotron Resonance (ICR) model and the Ion Parametric Resonance (IPR) Model in an attempt to explain the occurrence of resonance frequencies. This is extensively described here under the heading: Mechanisms behind the effects of electromagnetical fields upon biology. We also bring forward the concept of solitons being active in membranes and DNA/RNA-transcription as a, possible mean to understand and prove the biological effects of EMF. The Nishinomiya-Yukawa International and Interdisciplinary Symposium 2007 raised the question: What is Life? An obvious and simple answer could be: It is DNA! The DNA strand can be looked upon as an antenna resonating in the microwave band 6GHz with its harmonics and subharmonics.(14)-18)) If this holds true, the dramatic situation might exist, that all living organisms have a receptor for the newly constructed and world-wide man-made microvaves, leading to a direct effect upon the function of DNA - in concordance with our experimental findings! Our generation invented the microwave emitters. We now have in imperative obligation to further investigate the links between EMF and biology in order to prevent possible detrimental effects of the microwaves.
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| 49. |
- Sundgren, P, et al.
(författare)
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Paragangliomas of the spinal canal
- 1999
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 41:10, s. 788-794
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Tidskriftsartikel (refereegranskat)abstract
- We report the clinical MRI and histopathological features of five consecutive cases of spinal paraganglioma. Three intradural tumours were found in the typical location (two at the L4, one at the S2 level); one intradural extramedullary tumour arose at an unusual level, from the ventral C2 root, and one extradural tumour growing along the L5 nerve root sheath had an aggressive growth pattern with early, local paraspinal recurrence and, eventually, intradural metastatic spread. This type of growth pattern has not been described previously. Paragangliomas of the spinal canal are more common than previously thought and can be located anywhere along the spine, although the lumbosacral level is the most common. Their appearance on MRI can not distinguish them from other tumours in the spinal canal. Even though paragangliomas in general are benign and slowly growing their growth pattern can vary and be more aggressive, to the point of metastatic spread.
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| 50. |
- Sundgren, Pia, et al.
(författare)
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Value of conventional, and diffusion- and perfusion weighted MRI in the management of patients with unclear cerebral pathology, admitted to the intensive care unit
- 2002
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 44:8, s. 674-680
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Tidskriftsartikel (refereegranskat)abstract
- The aim of our retrospective study was to determine the extent to which diffusion- and perfusion- weighted MRI combined with conventional MRI could be helpful in the evaluation of intensive care unit (ICU) patients who have unknown or unclear cerebral pathology underlying a serious clinical condition. Twenty-one ICU patients with disparity between the findings on brain CT scan and their clinical status were studied. All patients underwent conventional MR and diffusion-weighted imaging and 14 also had MR perfusion studies. Abnormalities were present on diffusion-weighted imaging of 17 of the 21 patients and on perfusion-weighted studies of 7 of 14 patients. The MRI results changed the preliminary/working diagnosis in six patients. In eight other patients, MRI revealed additional pathology that had not been suspected clinically, and/or characterized more closely findings that had already been detected by CT or suspected clinically. MRI showed abnormalities in four of the five patients who had normal CT. MRI findings suggested a negative clinical outcome in all nine patients who subsequently died. MRI findings also suggested positive long-term outcome in five of nine patients who improved significantly as based on Glasgow and extended Glasgow outcome scales. In the three unconscious patients who had normal diffusion- and perfusion weighted imaging the clinical outcome was good. This study suggests that MRI in seriously ill ICU patients with unclear cerebral pathology can provide information that changes, characterizes, or supports diagnoses and/or prognoses and therefore facilitates further management.
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