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Sökning: WFRF:(Olsson Rolf) > Uppsala universitet

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  • Ericsson, Rolf (författare)
  • A Comparative Study of Head Development in Mexican Axolotl and Australian Lungfish: Cell Migration, Cell Fate and Morphogenesis
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The development of the vertebrate head is a complex process involving interactions between a multitude of cell types and tissues. This thesis describes the development of the cranial neural crest and of the visceral arch muscles in the head of two species. One, the Mexican axolotl (Ambystoma mexicanum), is a basal tetrapod, whereas the other, the Australian lungfish (Neoceratodus forsteri), belongs to the Dipnoi, the extant sister group of the Tetrapoda. The migration of neural crest cells, which form most of the bones and connective tissues in the head, and the morphogenesis of the jaw, was determined in the Mexican axolotl. It was shown that both the upper and lower jaws form from ventral condensations of neural crest cells in the mandibular arch. The dorsal condensation, earlier considered to give rise to the upper jaw, was shown to form the trabecula cranii.The normal spatio-temporal development of visceral arch muscles was investigated in both the Mexican axolotl and the Australian lungfish. In axolotl, the muscles tended to start forming almost simultaneously in all visceral arches at their future origins and extend towards their future insertions at the onset of muscle fibre formation. In lungfish, fibres formed simultaneously throughout most of each muscle anlage in the first and second visceral arch, but were delayed in the branchial arches. The anlagen were first observed at their future insertion, from which they developed towards future origins. To test the ability of neural crest cells to pattern the visceral arch muscles, migrating crest cells were extirpated from axolotl embryos, which resulted in a wide range of muscle malformations. In most cases, the muscles appeared in the right position but were small and extended in abnormal directions. This shows that neural crest cells are responsible not for the position of the muscles but for their correct anatomical pattern. Fate mapping showed that connective tissue surrounding myofibers is, at least partly, neural crest derived.In conclusion, the work presented in this thesis shows that although early development may map out the patterns of later development, the differences between axolotl and lungfish head development are not seen until during morphogenesis. Further investigation of morphogenesis is needed to explain the great variation of head morphology seen in vertebrates today.
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  • Wallerstedt, Sven, 1944, et al. (författare)
  • Abdominal tenderness in ascites patients indicates spontaneous bacterial peritonitis
  • 2007
  • Ingår i: European journal of internal medicine. - : Elsevier BV. - 0953-6205 .- 1879-0828. ; 18:1, s. 44-47
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Spontaneous bacterial peritonitis (SBP), which has been reported to be present in 10-30% of patients with cirrhotic ascites, may easily be overlooked. An important aim of our study was to determine whether there are any clinical signs which, in clinical practice, may predict or exclude SBP. Methods: We studied 133 patients with cirrhotic ascites from medical units at nine Swedish university hospitals where there had been at least one diagnostic ascites tap with analysis of polymorphonuclear leukocytes in the ascites fluid. The patients had initially been questioned about background factors and physically examined according to a standardized case record form. Samples of blood, urine, and ascites were then drawn for analysis according to a structured schedule. Results: SBP could be excluded in 80% of all the cases and was confirmed in 8% of the 133 patients in the final analysis. Abdominal pain and abdominal tenderness were more common in patients with SBP (p < 0.01), but no other physical sign or laboratory test could separate SBP cases from the others. Conclusions: SBP was present in about one-tenth of the hospitalized patients with cirrhotic ascites in this cohort. Performing repeated physical examinations and paying particular attention to abdominal tenderness may be the best way to become aware of the possible development of this complication.
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  • Aleman, Soo, et al. (författare)
  • Health check-ups and family screening allow detection of hereditary hemochromatosis with less advanced liver fibrosis and survival comparable with the general population
  • 2011
  • Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 46:9, s. 1118-1126
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective. The information concerning the morbidity and mortality of hereditary hemochromatosis is based primarily on clinical cohorts of symptomatic patients. The major aim of this study was to analyze the long-term prognosis for Swedish patients with this condition, with respect to both clinical features and survival, in relation to the route by which the disease was detected. Patients and methods. 373 patients with hemochromatosis detected through routine health checkups (n = 153), family screening (n = 44), symptoms of arthralgia (n = 23), investigation of other diseases/symptoms (n = 108) or signs of liver disease (n = 45) were monitored for a mean period of 11.9 +/- 5.8 years. The degree of liver fibrosis and survival were analyzed. Results. Overall survival among these patients was not significantly different from that of a matched normal population. The patients diagnosed through health check-ups and family screening were detected at an earlier age and had the highest rate of survival. Liver biopsy at the time of diagnosis revealed cirrhosis in 9% of those detected through the health check-ups and 5% in the case of family screening, compared with 13% for the group with arthralgia, 17% for other diseases/symptoms and 42% for liver disease. Conclusion. Health check-ups and family screening allow detection of hereditary hemochromatosis at an earlier age and with less advanced liver fibrosis, although a few of these patients have already developed cirrhosis. Our study indicates that iron indices should be included in health check-ups, and if abnormal, should lead to further investigation.
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  • Boisvert, Catherine Anne, 1978- (författare)
  • The Origin of Tetrapod Limbs and Girdles: Fossil and Developmental Evidence
  • 2009
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Around 375 million years ago, the first tetrapods appeared, marking one of the most important events in vertebrate evolutionary history. The fin to limb transition saw the appearance of fingers and a weight bearing pelvic girdle. While very little research has been done on the evolution of the tetrapod pelvic girdle, a fair amount has been done on the origins of fingers but some aspects remained controversial. A combination of palaeontology, developmental biology and comparative morphology was therefore used in this thesis to better understand the fin to limb transition. The pectoral fin of Panderichthys, a sarcopterygian fish closely related to tetrapods was CT-scanned and modeled in three dimensions and its pelvic girdle and fin were examined with traditional techniques. This information from the fossil record was integrated with comparisons of the development of the Australian lungfish, Neoceratodus forsteri, our closest living fish relative and the axolotl (Ambystoma mexicanum), a salamander representing well the condition of early tetrapods. Development of bone and cartilage was studied through clearing and staining and development of skeletal muscles through immunostaining. In situ hybridizations were performed on the lungfish to study the expression of Hoxd13, associated with the formation of digits in tetrapods. This work shows that the late expression phase of Hoxd13 is present in Neoceratodus and is associated with the formation of radials. Redescription of the pectoral fin of Panderichthys reveals that distal radials are present, which, in addition to other information, lead us to conclude that digits are not novelties in tetrapods but rather have evolved from the distal radials present in the fins of all sarcopterygian fish. The earliest tetrapods lack a full set of wrist + carpals/ankle + tarsal bones. Here, we propose that this region of the limbs evolved after fingers and toes through an expansion of the region between the proximal limb bones and the digits. As for the pelvic girdle, it is very primitive in Panderichthys but comparison of its development in Neoceratodus and Ambystoma suggest that the ischium evolved through the posterior expansion of the pubis and the ilium, through an elongation of the iliac process already present in sarcopterygian fishes. The results of this thesis help to better understand the fin to limb transition and show that it is more gradual than previously believed.  
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  • Bornefalk Hermansson, Anna, 1971- (författare)
  • Resampling Evaluation of Signal Detection and Classification : With Special Reference to Breast Cancer, Computer-Aided Detection and the Free-Response Approach
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The first part of this thesis is concerned with trend modelling of breast cancer mortality rates. By using an age-period-cohort model, the relative contributions of period and cohort effects are evaluated once the unquestionable existence of the age effect is controlled for. The result of such a modelling gives indications in the search for explanatory factors. While this type of modelling is usually performed with 5-year period intervals, the use of 1-year period data, as in Paper I, may be more appropriate.The main theme of the thesis is the evaluation of the ability to detect signals in x-ray images of breasts. Early detection is the most important tool to achieve a reduction in breast cancer mortality rates, and computer-aided detection systems can be an aid for the radiologist in the diagnosing process.The evaluation of computer-aided detection systems includes the estimation of distributions. One way of obtaining estimates of distributions when no assumptions are at hand is kernel density estimation, or the adaptive version thereof that smoothes to a greater extent in the tails of the distribution, thereby reducing spurious effects caused by outliers. The technique is described in the context of econometrics in Paper II and then applied together with the bootstrap in the breast cancer research area in Papers III-V.Here, estimates of the sampling distributions of different parameters are used in a new model for free-response receiver operating characteristic (FROC) curve analysis. Compared to earlier work in the field, this model benefits from the advantage of not assuming independence of detections in the images, and in particular, from the incorporation of the sampling distribution of the system's operating point.Confidence intervals obtained from the proposed model with different approaches with respect to the estimation of the distributions and the confidence interval extraction methods are compared in terms of coverage and length of the intervals by simulations of lifelike data.
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  • Burmakin, Mikhail, et al. (författare)
  • Imatinib increases oxygen delivery in extracellular matrix-rich but not in matrix-poor experimental carcinoma
  • 2017
  • Ingår i: Journal of Translational Medicine. - : BioMed Central. - 1479-5876 .- 1479-5876. ; 15
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Imatinib causes increased turnover of stromal collagen, reduces collagen fibril diameter, enhances extracellular fluid turnover and lowers interstitial fluid pressure (IFP) in the human colonic carcinoma KAT-4/HT-29 (KAT-4) xenograft model. Methods: We compared the effects of imatinib on oxygen levels, vascular morphology and IFP in three experimental tumor models differing in their content of a collagenous extracellular matrix. Results: Neither the KAT4 and CT-26 colonic carcinoma models, nor B16BB melanoma expressed PDGF beta-receptors in the malignant cells. KAT-4 tumors exhibited a well-developed ECM in contrast to the other two model systems. The collagen content was substantially higher in KAT-4 than in CT-26, while collagen was not detectable in B16BB tumors. The pO(2) was on average 5.4, 13.9 and 19.3 mmHg in KAT-4, CT-26 and B16BB tumors, respectively. Treatment with imatinib resulted in similar pO(2)-levels in all three tumor models but only in KAT-4 tumors did the increase reach statistical significance. It is likely that after imatinib treatment the increase in pO(2) in KAT-4 tumors is caused by increased blood flow due to reduced vascular resistance. This notion is supported by the significant reduction observed in IFP in KAT-4 tumors after imatinib treatment. Vessel area varied between 4.5 and 7% in the three tumor models and was not affected by imatinib treatment. Imatinib had no effect on the fraction of proliferating cells, whereas the fraction of apoptotic cells increased to a similar degree in all three tumor models. Conclusion: Our data suggest that the effects of imatinib on pO(2)-levels depend on a well-developed ECM and provide further support to the suggestion that imatinib acts by causing interstitial stroma cells to produce a less dense ECM, which would in turn allow for an increased blood flow. The potential of imatinib treatment to render solid tumors more accessible to conventional treatments would therefore depend on the degree of tumor desmoplasia.
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