| 1. |
- Sundström, Johan, Professor, 1971-, et al.
(författare)
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Risk factors for subarachnoid haemorrhage : a nationwide cohort of 950 000 adults
- 2019
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Ingår i: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 48:6, s. 2018-2025
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Subarachnoid haemorrhage (SAH) is a devastating disease, with high mortality rate and substantial disability among survivors. Its causes are poorly understood. We aimed to investigate risk factors for SAH using a novel nationwide cohort consortium.METHODS: We obtained individual participant data of 949 683 persons (330 334 women) between 25 and 90 years old, with no history of SAH at baseline, from 21 population-based cohorts. Outcomes were obtained from the Swedish Patient and Causes of Death Registries.RESULTS: During 13 704 959 person-years of follow-up, 2659 cases of first-ever fatal or non-fatal SAH occurred, with an age-standardized incidence rate of 9.0 [95% confidence interval (CI) (7.4-10.6)/100 000 person-years] in men and 13.8 [(11.4-16.2)/100 000 person-years] in women. The incidence rate increased exponentially with higher age. In multivariable-adjusted Poisson models, marked sex interactions for current smoking and body mass index (BMI) were observed. Current smoking conferred a rate ratio (RR) of 2.24 (95% CI 1.95-2.57) in women and 1.62 (1.47-1.79) in men. One standard deviation higher BMI was associated with an RR of 0.86 (0.81-0.92) in women and 1.02 (0.96-1.08) in men. Higher blood pressure and lower education level were also associated with higher risk of SAH.CONCLUSIONS: The risk of SAH is 45% higher in women than in men, with substantial sex differences in risk factor strengths. In particular, a markedly stronger adverse effect of smoking in women may motivate targeted public health initiatives.
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| 2. |
- Bergström, Göran, 1964, et al.
(författare)
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Prevalence of Subclinical Coronary Artery Atherosclerosis in the General Population
- 2021
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Ingår i: Circulation. - Philadelphia : American Heart Association. - 0009-7322 .- 1524-4539. ; 144:12, s. 916-929
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Tidskriftsartikel (refereegranskat)abstract
- Background: Early detection of coronary atherosclerosis using coronary computed tomography angiography (CCTA), in addition to coronary artery calcification (CAC) scoring, may help inform prevention strategies. We used CCTA to determine the prevalence, severity, and characteristics of coronary atherosclerosis and its association with CAC scores in a general population.Methods: We recruited 30 154 randomly invited individuals age 50 to 64 years to SCAPIS (the Swedish Cardiopulmonary Bioimage Study). The study includes individuals without known coronary heart disease (ie, no previous myocardial infarctions or cardiac procedures) and with high-quality results from CCTA and CAC imaging performed using dedicated dual-source CT scanners. Noncontrast images were scored for CAC. CCTA images were visually read and scored for coronary atherosclerosis per segment (defined as no atherosclerosis, 1% to 49% stenosis, or ≥50% stenosis). External validity of prevalence estimates was evaluated using inverse probability for participation weighting and Swedish register data.Results: In total, 25 182 individuals without known coronary heart disease were included (50.6% women). Any CCTA-detected atherosclerosis was found in 42.1%; any significant stenosis (≥50%) in 5.2%; left main, proximal left anterior descending artery, or 3-vessel disease in 1.9%; and any noncalcified plaques in 8.3% of this population. Onset of atherosclerosis was delayed on average by 10 years in women. Atherosclerosis was more prevalent in older individuals and predominantly found in the proximal left anterior descending artery. Prevalence of CCTA-detected atherosclerosis increased with increasing CAC scores. Among those with a CAC score >400, all had atherosclerosis and 45.7% had significant stenosis. In those with 0 CAC, 5.5% had atherosclerosis and 0.4% had significant stenosis. In participants with 0 CAC and intermediate 10-year risk of atherosclerotic cardiovascular disease according to the pooled cohort equation, 9.2% had CCTA-verified atherosclerosis. Prevalence estimates had excellent external validity and changed marginally when adjusted to the age-matched Swedish background population.Conclusions: Using CCTA in a large, random sample of the general population without established disease, we showed that silent coronary atherosclerosis is common in this population. High CAC scores convey a significant probability of substantial stenosis, and 0 CAC does not exclude atherosclerosis, particularly in those at higher baseline risk.
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| 3. |
- Carlsson, Anders, 1980-
(författare)
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Role of mast cells and probiotics in the regulation of intestinal barrier function
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The intestinal mucosa is the largest contact area and one of the most important barriers to the outside environment. It is highly specialized in aiding us digest and absorb nutrients. It is daily exposed to several potentially dangerous substances and microorganisms, which if they were allowed to pass into the body, could give rise to diseases. Throughout the small intestine certain sites specialized in antigen sampling are found. These sites are named Peyer’s patches and are lymphoid follicles. The epithelium covering the Peyer’s patches is called follicle-associated epithelium and is specialized in antigen sampling and uptake. The special epithelium enables presentation of luminal antigen to immune cells in the underlying follicle.Persistent life stress and stressful life events affect the course of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) through largely unknown mechanisms. Regulation of epithelial permeability to antigens is crucial for the balance between inflammation and immune-surveillance, and increased intestinal permeability has been shown in patients with ulcerative colitis and Crohns disease. Vasoactive intestinal polypeptide (VIP) and corticotropin-releasing factor have been implicated as important mediators of stress-induced abnormalities in intestinal mucosal functions in animal models. Both of these mediators have been reported to regulate bowel ion secretion in humans during stress and uptake of horseradish peroxidase in rodents. Probiotics have been shown to ameliorate the deleterious effects of stress on intestinal function, but mechanisms remain to be elucidated.The aim of this thesis was to elucidate whether mast cells play an important role in intestinal barrier function during stress and inflammation. Moreover, we wanted to determine whether probiotics can ameliorate the mucosal barrier integrity during stress and inflammation.To study the function of mast cells we conducted in vitro experiments on cell lines and ex vivo experiments in Ussing chambers on mouse, rat and human intestinal tissue. The Ussing chamber technique measures electrophysiological properties of the tissue and also gives the possibility to study transcellular and paracellular passage of markers and bacteria. Immunohistology and confocal microscopy have been used to identify mast cells and receptors of interest.Our results show that stress affects the follicle-associated epithelium barrier by mechanisms involving VIP and mast cells. These findings were corroborated by the localization of VIP receptors on mucosal mast cells. Furthermore, pretreatment with probiotics was effective in protecting the gut against stress-induced intestinal barrier dysfunction and mucosal inflammation. This protection appeared to involve a mast cell and peroxisome proliferatoractivated receptor-γ dependent mechanism.
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| 4. |
- Dahlman, Pär
(författare)
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CT Urography : Efforts to Reduce the Radiation Dose
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Computed tomography urography (CTU) is today the imaging method used to investigate patients with suspected urinary tract malignancy, replacing the old imaging method intravenous pyelography (IVP) about a decade ago. The downside of this shift was that the effective radiation dose to the examined patient was eight times higher for CTU compared to IVP. Based on four different studies, the present thesis focused on efforts to reduce the CTU radiation dose. In study I, the number of cysts and solid lesions in the separate scan phases was evaluated in 57 patients undergoing four-phase CTU 1997-98. The number of scans was reduced from four to three when the nephrographic scan was abolished following study I.Study II registered the diameter of renal cell carcinoma (RCC) and the presenting symptoms in the total number of patients (n=232) diagnosed with RCC between 1997 and 2003. The results from study II showed that the critical size for RCCs to cause macroscopic hematuria was ≥ 4 cm. Study III was a dose-escalation study aimed to decide the minimal possible tube load in the unenhanced and excretory phase scans if the low dose images are reviewed together with normal dose corticomedullary phase images. Study III showed that it is possible to reduce the mean effective dose in three phase CTU from 16.2 mSv to 9.4 mSv with a combined low and normal dose CTU protocol. Study IV investigated the changes in the CTU protocol between 1997 and 2008, and the development of the effective radiation dose. Study IV clarified how the CTU protocol has changed between 1997 and 2008 and as a result the mean effective radiation dose to patients undergoing CTU in 2008 is only 39% of the effective dose in 1997. In conclusion, the findings from the studies included in this thesis have contributed to a reduced radiation dose to patients undergoing CTU. The mean effective dose from CTU is at present only three times higher compared to that from the IVP.
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| 5. |
- Dimopoulou, Angeliki, 1975-
(författare)
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CT with 3D-Image Reconstructions in Preoperative Planning
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Computed tomography is one of the most evolving fields of modern radiology. The current CT applications permit among other things angiography, 3D image reconstructions, material decomposition and tissue characterization. CT is an important tool in the assessment of specific patient populations prior to an invasive or surgical procedure. The aim of this dissertation was to demonstrate the decisive role of CT with 3D-image reconstructions in haemodialysis patients scheduled to undergo fistulography, in patients undergoing surgical breast reconstructions with a perforator flap and in patients with complicated renal calculi scheduled to undergo percutaneous nephrolithotomy.CT Angiography with 3D image reconstructions was performed in 31 patients with failing arteriovenous fistulas and grafts, illustrating the vascular anatomy in a comprehensive manner in 93.5% of the evaluated segments and demonstrating a sensitivity of 95% compared to fistulography.In 59 mastectomy patients scheduled to undergo reconstructive breast surgery with a deep inferior epigastric perforator flap, the preoperative planning with CT Angiography with 3D image reconstructions of the anterior abdominal wall providing details of its vascular supply, reduced surgery time significantly (p< 0.001) and resulted in fewer complications.Dual Energy CT Urography with advanced image reconstructions in 31 patients with complicated renal calculi scheduled to undergo PNL, resulted in a new method of material characterisation (depicting renal calculi within excreted contrast) and in the possibility of reducing radiation dose by 28% by omitting the nonenhanced scanning phase. Detailed analysis of the changes renal calculi undergo when virtually reconstructed was performed and a comparison of renal calculi number, volume, height and attenuation between virtual nonenhanced and true nonenhanced images was undertaken. All parameters were significantly underestimated in the virtual nonenhanced images.CT with 3D-reconstructions is more than just “flashy images”. It is crucial in preoperative planning, optimizes various procedures and can reduce radiation dose.
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| 6. |
- Hadimeri, Ursula
(författare)
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Factors affecting the physical characteristics of arterio-venous fistula in patients with renal failure
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and PurposeA patent access is vital for a dialysis patient. The arterio-venous fistula (AVF), the most important access for haemodialysis (HD), is frequently affected by extensive complications such as stenosis and occlusions.Study I: To investigate whether the dimensions of AVFs used for performing haemodialysis were affected by the original disease.Study II: To investigate if the diameter of the distal radiocephalic fistula could influence left ventricular variables in stable haemodialysis patients.Study III: To investigate whether a single Far Infrared (FIR) light treatment could alter blood velocity, AVF diameter or inflammatory markers.Study IV: To evaluate in what extent the renal diagnosis and radiological interventions affected the dysfunction of AVF and results of percutaneous transluminal angioplasty (PTA).Materials and methodsStudy I: The lumen diameter of the AVF was studied by ultrasound in 19 patients with autosomal dominant polycystic kidney disease (ADPKD) and in 19 control patients. The monitoring was performed along the forearm part of the vein, the maximal diameter was measured. The diameters of the two needle insertion sites were also measured.Study II: Nineteen patients were investigated with echocardiography, using M-mode recordings and measurements in the 2D image. Ultrasound and doppler ultrasound were performed. Transsonic measurements were performed after the ultrasound investigation. Measurements of the diameter of the AVF were performed in four locations. Heart variables were analysed regarding left ventricular (LV) criteria.Study III: Thirty patients with native AVF in the forearm were included. Each patient was his/her own control. Ultrasound examinations of the AVF diameter and blood flow velocity were performed before and after a single Far Infrared light (FIR) treatment.Study IV: 522 radiological investigations and endovascular treatments between January 1, 2006 and December 31, 2014 were analysed in 174 patients, retrospectively. All investigations had been performed due to clinical suspicion of impaired AVF function. All stenoses were evaluated and the number, degree, length, location and relation to anastomosis were recorded. After PTA the remaining stenoses were evaluated again and complications were recorded.ResultsStudy I: The diameter of the AVF at the maximal site in patients with ADPKD was significantly wider than that for the control patients.Study II: A larger AVF mean and maximal diameter worsened left ventricular characteristics.Study III: A single FIR treatment resulted in a significant increase in blood velocity over the AV fistula from a mean of 2.1±1.0 m/s to 2.3±1.0 m/s. The diameter of the arterialized vein became wider, i.e. 0.72±0.02 to 0.80±0.02 cm. The increase in fistula blood velocity correlated positively with baseline serum-urate and the increase in venous diameter correlated positively with the baseline plasma orosomucoid concentration.Study IV: The degree of AVF stenosis before PTA correlated significantly with the degree of remaining stenosis after intervention. Arterial stenosis was significantly more frequent among patients with diabetic nephropathy and interstitial nephritis. A shorter life span between PTAs was related to diabetic nephropathy.ConclusionsStudy I: The receiving veins of AVF in patients with ADPKD have an abnormality that causes a greater than normal dilatation in response to the arterialization.Study II: The maximal diameter of the distal AVF seems to be a sensitive marker of LV impairment in stable haemodialysis patients.Study III: A single FIR treatment increased AVF blood velocity and vein diameter. Thus, one FIR treatment can help maturation of AVF in the early postoperative course.Study IV: Repeated PTA was performed significantly more often in patients with diabetic nephropathy. Clinically significant stenosis should be dilated as soon as possible. Occlusion of the AVF should be thrombolyzed and/or dilated when diagnosed.
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| 7. |
- Lundin, Margareta
(författare)
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Aspects on Image Quality in Radiologic Evaluation of the Urinary Tract
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this document is on image quality as one of the factors fundamental for the diagnostic process. With the rising number of procedures and the trend towards more complicated examinations, urinary tract investigations was chosen in this work as a good clinical model for evaluation of the factors influencing image quality and of the ways of evaluating image quality.In paper I, a method is described for optimisation during the introduction of a new imaging system, with a focus on the maintenance of image quality relative to the older already optimised system. Image quality was assessed using the image criteria of the European guidelines for IVU with visual grading analysis. Equivalent image quality in image pairs was achieved at 30% of the dose. The CDRAD contrast-detail phantom makes it possible to find dose levels that give equal image quality using different imaging systems.In paper II, the influence of bowel purgation on image quality in urography is questioned. The aim of this study was to compare bowel purgation and two other preparation methods; dietary restrictions and no preparation at all. Image quality was assessed according to European Commission criteria for excretory urography. The effectiveness of bowel purgation and the amount of residual gas were scored separately. The results of our study show that the preparation methods are of equal value and further use of bowel purgation before excretory urography cannot be justified.In paper III, the image quality of the non-enhanced series is compared to a virtual noncontrast series obtained using two generations of dual-energy CT scanners and taking CT of the urinary tract as a model. The image quality of the VNC images was rated inferior to the single-energy variant for both scanners, the OR range being 11.5–67.3 for the Definition and 2.1–2.8 for the Definition Flash. Visual noise and overall quality were regarded as better with Flash than with Definition. Image quality of VNC images obtained with the new generation of DECT is still slightly inferior compared to native images.In paper IV, the accuracy of measurement of renal calculi in a dual-energy, virtual, nonenhanced-image series is compared to actual stone size and a single-energy image series in the phantom study. This study shows that detection of small stones is not reliable, despite better image quality, with the new DECT and that small stones will be missed with VNC imaging. With larger stones, the inherent measurement error with CT is magnified with VNC imaging.
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| 8. |
- Helenius, Malin, 1978-
(författare)
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Investigation of Bladder Tumors with CT Urography in Patients Presenting with Gross Hematuria
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bladder tumor is the most common tumor detected in patients presenting with gross hematuria. Early detection and treatment is crucial for good prognosis, however, delay in diagnosis and treatment is common. Routine work-up of gross hematuria includes cystoscopy and Computed Tomography Urography (CTU). If CTU has a high detection rate of bladder tumor, it can be used to direct further investigation of the patient, hopefully reducing delay to diagnosis and treatment. There is no consensus on which phase the bladder should be assessed at CTU. Assessment of the bladder in an early contrast-enhancing phase requires contrast material enhancement in bladder tumors and a bladder that is properly distended with urine. For patients younger than 50 years, the routine CTU protocol used for examining gross hematuria patients included unenhanced (UE), corticomedullary phase (CMP), and excretory phase (EP), with the start of the scan being enhancement triggered: patients aged 50 years or older followed the same protocol plus a nephrographic phase (NP).The CTU protocol was compared with flexible cystoscopy for detecting bladder tumors. Sensitivity for bladder cancer detection was equal for CTU and cystoscopy (0.87).Patients diagnosed with bladder cancer (n=50) were examined during UE, CMP, and EP, and 21 patients were additionally examined in NP. The highest mean tumor contrast enhancement was seen in CMP (37 HU).The CMP, NP, and EP in 106 patients were randomized into an evaluation order (n=318 different phases) and blindly reviewed by two uroradiologists. In CMP, sensitivity (0.95) and negative predictive value (0.99) were higher than in NP and EP.Four different preparation protocols for achieving bladder distension were compared. The protocol that included drinking 1 l of fluid during a two-hour period prior to examination without voiding during that period, gave satisfactory bladder distension without causing unacceptable patient discomfort and having the lowest compliance. Gross hematuria patients should be primarily examined with CTU including UE, CMP and EP to direct further investigation of the patients. The patients should follow a preparation protocol including drinking 1 l of fluid during a two-hour period before examination and not voiding during that period.
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| 9. |
- Magnusson, Anders, 1957-
(författare)
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Evaluation of surgically assisted rapid maxillary expansion and orthodontic treatment : Effects on dental, skeletal and nasal structures and rhinological findings
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Surgically Assisted Rapid Maxillary Expansion (SARME) is frequently used to treat skeletal maxillary transverse deficiency (MTD) in skeletally mature and non-growing individuals. Despite previous research in the field, questions remain with respect to the long-term stability of SARME and its effects on hard and soft tissue.The overall aim of the present doctoral work was to achieve a greater understanding of SARME, using modern image technology and a multidisciplinary approach, with special reference to effects on the hard and soft tissues and respiration. A more specific aim was to evaluate the long-term stability in a retrospective sample of patients treated with SARME and orthodontic treatment and to compare the results with a matched, untreated control group. The studies in this doctoral project are thus based on two different samples and study designs.The first sample, Study I (Paper I), is a retrospective, consecutive, long-term follow-up material of study models from 31 patients (17 males and 14 females) treated with SARME and orthodontic treatment between 1991 and 2000. The mean pre-treatment age was 25.9 years (SD 9.6) with a mean follow-up time of 6.4 years (SD 3.3). Direct measurements on study models were made with a digital sliding caliper at reference points on molars and canines. To evaluate treatment outcome and long-term stability, the results were compared with study models from an untreated control group, matched for age, gender and follow-up time.The second sample, Study II (Papers II-IV), is a prospective consecutive, longitudinal material of 40 patients scheduled to undergo SARME and orthodontic treatment between 2006 and 2009.In Paper II, one patient was excluded because of a planned adenoidectomy. The final sample comprised 39 patients (16 males and 23 females). The mean age at treatment start was 19.9 years (range 15.9 – 43.9). Acoustic rhinometry, rhinomanometry and a questionnaire were used to assess the degree of nasal obstruction at three time-points; pre-treatment, three months after expansion and after completed treatment (mean 18 months).In Papers III–IV, three patients declined to participate and two had to be excluded because their CT-records were incomplete. The final sample comprised 35 patients (14 males and 21 females). The mean age at treatment start was 19.7 years (range 16.1 – 43.9). Helical CT-images were taken pre-treatment and eighteen months’ post-expansion. 3D models were registered and superimposed at the anterior cranial base. The automated voxel-based image registration method allows precise, accurate measurements in all areas of the maxilla. In Papers II–IV, the treatment groups constituted their own control groups.The main findings in the retrospective, long-term follow-up study were that SARME and orthodontic treatment normalized the transverse discrepancy and was stable for a mean of 6 years post-treatment. Pterygoid detachment did not entirely eliminate the side effect of buccal tipping of the posterior molars. Relapse is time-related and is most pronounced during the first 3 years after treatment. Thus the retention period should be extended and should be considered for this period. The main rhinological findings in the prospective longitudinal study were that SARME had a shortterm, favourable effect on nasal respiration, but the effect did not persist in the long-term. However, subjects with pre-treatment nasal obstruction reported a lasting sensation of improved nasal function.SARME and orthodontic treatment had a significant but non-uniform skeletal treatment effect, with significantly greater expansion posteriorly than anteriorly. The expansion was parallel anteriorly but not posteriorly. The lateral tipping of the posterior segment was significant, despite careful surgical separation. No correlation was found between tipping and the patient's age. Furthermore, SARME and orthodontic treatment significantly affected all dimensions of the external features of the nose. The most obvious changes were at the most lateral alar-bases. The difference in lateral displacement profoundly influenced the perception of a more rounded nose. There were no predictive correlations between the changes. Patients with narrow and constrained nostrils can benefit from these changes with respect to the subjective experience of nasal obstruction. It is questionable whether an alar-cinch suture will prevent widening at the alar-base.The 3D superimposition applied in Study II is a reliable method, circumventing projection and measurement errors. In conclusion, SARME and orthodontic treatment normalize the transverse deficiency, with long-term stability. SARME has a favourable effect on the subjective perception of nasal respiration. SARME significantly affects dental, skeletal and nasal structures.
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| 10. |
- Magnusson, Jörgen
(författare)
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Rethinking the Gospel of Truth : A Study of its Eastern Valentinian Setting
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Already in the second century, the Church Father Irenaeus warned against reading the Gospel of Truth that was used among the so-called Valentinians. For more than one and a half millennium GospTruth was lost until in the 1950s a Coptic text was discovered that could be a translation of that work both loved and hated.Since the discovery scholars have tried to determine whether the Coptic text represents the one mentioned by Irenaeus, and whether its author might even be the famous Gnostic teacher Valentinus of Alexandria.The text is very complex and the present study the first attempt to use text linguistic tools for analysing GospTruth. A new and sometimes radically different translation is presented, and an hypothesis of date of redaction and authorship is put forward. Previously Gnostic texts have usually been read in light of the reports of the Church Fathers. In this study an attempt is made to detect topics that were interesting for the Valentinians and that have so far been neglected. The analysis presents a new ethical debate among early Christians regarding the Biblical law, and a hypothesis of how the author of GospTruth wanted his or her community to act towards the neighbouring communities is elaborated. In addition my investigation draws attention to an interpretation of the crucifixion that seems to have distinguished Valentinians from others.For a long time scholars depicted the Gnostics as evil opponents to the church. During the last decades this view has been criticized, and today many scholars abandon the term Gnostic altogether, and instead only use the term Christian. In my opinion such an approach risks to conceal the unique features of Valentinianism, and the results of the present study will hopefully shed new light on a branch of Christianity which still is relatively unexplored.
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