| 31. |
- Persson, Josefine, et al.
(författare)
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Aqueous polymer two-phase systems formed by new thermoseparating polymers
- 2000
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Ingår i: Bioseparation. - 1573-8272. ; 9:2, s. 105-116
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Tidskriftsartikel (refereegranskat)abstract
- A set of new polymers that can be used as phase forming components in aqueous two-phase systems is presented. All polymers studied have thermoseparating properties i.e. form one separate polymer enriched phase and one aqueous solution when heated above the critical temperature. This property makes the polymers attractive alternatives to the polymers used in traditional aqueous two-phase systems such as poly(ethylene glycol) (PEG) and dextran. The thermal phase separation simplifies recycling of the polymers, thus making the aqueous two-phase systems more cost efficient and suitable for use in large scale. Thermoseparating polymers studied have been copolymers of ethylene oxide and propylene oxide (EO-PO), poly (N-isopropylacrylamide) (poly-NIPAM), poly vinyl caprolactam (poly-VCL) and copolymers of N-isopropylacrylamide and vinyl caprolactam with vinyl imidazole (poly(NIPAM-VI) and poly(VCL-VI), respectively). In addition, the copolymer poly(NIPAM-VI) has the property to be uncharged at pH above 7.0 and positively charged at lower pH. This allows the partitioning of protein to be directed by changing the pH in the system instead of the traditional addition of salt to direct the partitioning. Hydrophobically modified EO-PO copolymer (HM-(EO-PO)) with alkyl groups (C_{14}) at both ends forms two-phase system with for example poly(NIPAM-VI). The phase diagram for poly(NIPAM-VI)/HM-(EO-PO) was determined and the model proteins lysozyme and BSA were partitioned in this system. For BSA in poly(NIPAM-VI)/HM-(EO-PO) system a change in pH from 8.0 to 5.4 results in a change of partition coefficient from K=0.8 to K=5.1, i.e. BSA could be transferred from the HM-(EO-PO) phase to the poly(NIPAM-VI) phase. BSA partitioning in poly(NIPAM-VI)/HM-(EO-PO) system allows quantitative BSA recovery, and recoveries of poly(NIPAM-VI) and HM-(EO-PO) were 53% and 92%, respectively, after the thermoseparation step.
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| 32. |
- Persson, Magnus, et al.
(författare)
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A new non-invasive ultrasonic method for simultaneous measurements of longitudinal and radial arterial wall movements: first in vivo trial.
- 2003
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 23:5, s. 247-251
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Tidskriftsartikel (refereegranskat)abstract
- During recent years, the radial movement of the arterial wall has been extensively studied, and measurements of the radial movement are now an important tool in cardiovascular research for characterizing the mechanical properties of the arterial wall. In contrast, the longitudinal movement of vessels has gained little or no attention as it has been presumed that this movement is negligible. With modern high-resolution ultrasound, it can, however, be seen that the intima-media complex of the arterial wall moves not only in the radial direction, but also in the longitudinal direction during pulse-wave propagation. This paper describes a new non-invasive ultrasonic method that is able to measure simultaneously two dimensionally arterial vessel wall movements. The method is demonstrated in a limited in vivo trial. Results from the in vivo trial show that, apart from the well-known radial movement, there is a distinct longitudinal movement in the human common carotid artery with, in this case, the intima-media complex moving substantially as compared with the region of the tunica adventitia. Two-dimensional evaluation of the vessel-wall movements, taking not only the radial movement, but also the longitudinal movement into account, may provide novel information of importance in the evaluation of vessel-wall function.
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| 33. |
- Persson, Mikael, et al.
(författare)
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[Lu-177]pertuzumab : Experimental therapy of HER-2-expressing xenografts
- 2007
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 67:1, s. 326-331
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Tidskriftsartikel (refereegranskat)abstract
- Pertuzumab (Omnitarg) is a novel antibody against HER-2, domain II. HER-2 is a tyrosine kinase receptor that is overexpressed in several carcinomas, especially breast cancer. Pertuzumab, labeled with the low-energy beta emitter Lu-177, might be a candidate for targeted radiotherapy of disseminated HER-2-positive micrometastases. The radiolabeled antibody [Lu-177]pertuzumab showed favorable targeting properties in BALB/c (nu/nu) mice with HER-2-overexpressing xenografts. The absorbed dose in tumors was more than five times higher than the absorbed dose in blood and more than seven times the absorbed dose in any other normal organ. Experimental therapy showed that [Lu-177]pertuzumab delayed tumor progression compared with controls (no treatment, P < 0.0001; nonlabeled pertuzumab antibody, P < 0.0001; and Lu-177-labeled irrelevant antibody, P < 0.01). No adverse side effects of the treatment could be detected. Thus, the experimental results support the planning of clinical studies applying [Lu-177]pertuzumab for therapy.
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| 34. |
- Persson, Magnus, et al.
(författare)
-
Non-invasive measurement of arterial longitudinal movement
- 2002
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Ingår i: Proceedings of the IEEE Ultrasonics Symposium. - 1051-0117. ; 2, s. 1783-1786
-
Konferensbidrag (refereegranskat)abstract
- In arterial vessel wall characterisation the longitudinal movements of vessels have gained little or no attention. It has been presumed that the arterial vessels move very little in the longitudinal direction. With modern high resolution ultrasound it can, however, be seen that arterial vessels move not only in the circumferential, but also in longitudinal direction. This paper describes a non-invasive, ultrasound based method which estimates the longitudinal and the circumferential movement, respectively. The method is demonstrated in a limited in vivo study of the common carotid artery. Results show that, apart from the well known circumferential movement, there is a distinct longitudinal movement.
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| 35. |
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| 36. |
- Persson, P. O.Å., et al.
(författare)
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Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 122:15
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Tidskriftsartikel (refereegranskat)abstract
- Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1-xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrödinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (∼9 × 10 12 cm-2) as the non-graded conventional structure, though the mobility drops from ∼ 2360 cm2/V s in the conventional to ∼ 960 cm2/V s in the graded structure. The transconductance gm of the linearly graded channel HEMTs is shown to be flatter with smaller g m ′ and g m ″ as compared to the conventional non-graded channel HEMT implying improved device linearity.
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| 37. |
- Persson, Sylvi, et al.
(författare)
-
Increased blood viscosity and decreased red cell filterability in patients with dilated cardiomyopathy
- 1991
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Ingår i: 7th European Conference on Clinical Haemorheology, Southampton, United Kingdom, July 16-19, 1991..
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Konferensbidrag (refereegranskat)abstract
- Abstract Rheological properties o f blood were studied in eight patients with dilated cardiomyopathy (DCM) and ten healthy controls . Whole blood viscosity was measured at 4 different shear rates, using a computer controlled rotational viscometer. Patients had significantly higher blood viscosity at all shear rates, both at the patients natural hematocrits and after in vitro adjustment of sample hematocrits to 45%. Erythrocyte filterability measured by St George's Filtrometer and expressed as red cell transit time (RCTT) were significantly lower in patients. Hematocrits were higher but not statistically significant. No differences were found regarding plasma viscosity, leucocyte count and leucocyte filterability. The blood rheology changes found in this study may contribute to myocardial perfusion disturbances, which have been suggested a s a cause for DCM. The coronary blood flow reserve is reduced in patients with DCM as well as in patients with angina pectoris, both with and without coronary artery stenosis (Syndrome X). In all three patients cathegories we have found increased blood viscosity but DCM differs by by normal plasma viscosity.
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| 38. |
- Persson, Sylvi, et al.
(författare)
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Studies on blood rheology in patients with primary pulmonary hypertension
- 1990
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Ingår i: 32nd Annual Meeting of the International College of Angiology, Toronto, Canada, June 24-29, 1990.
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Konferensbidrag (refereegranskat)abstract
- Abstract Background: Disturbances of blood rheology may create unfavorable changes of blood flow. The present study was performed to reveal possible hemorheologic abnormalities in primary pulmonary hypertension. Methods: Six patients with primary pulmonary hypertension (PPH) and 10 healthy controls of comparable age and smoking habits were studied. Blood viscosity was studied with a computer-controlled rotational viscometer, at natural hematocrit and at standardized hematocrit (45%). A capillary U-tube was used for plasma viscosity studies. Blood cell filterability was measured by theSt. George's Filtrometer (according to Dormandy et a1). Nucleopore filters of 5 (erythrocytes) and 8 (leukocytes) micrometers were used. Results: Whole blood viscosity in PPH patients was higher than in controls at four different shear rates (p<0.025-0.005). This was partly due to a higher concentration of red cells in the patients. After standardization to 45% however, the difference was still there at the highest shear rate used (40 s-1). It was also found that the passage time for erythrocytes through the filter was increased in the patient group, indicating decreased erythrocyte deformability. There were no significant differences between the groups in plasma viscosity, plasma fibrinogen, concentration of leukocytes, or leukocyte deformability. Conclusions: Patients with PPH show increased whole blood viscosity values. This is partly explained by an increased hematocrit. It is also found, however, that the deformability of erythrocytes in these patients is decreased. These changes may influence blood flow in an unfavorable way. Therapeutic measures against hemorheologic disturbances may be a possible complement to the commonly used vasodilatory treatment.
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| 39. |
- Persson, Sylvi Ulrika, et al.
(författare)
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Studies on blood rheology in patients with primary pulmonary hypertension
- 1991
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Ingår i: Angiology. - New York, USA : Westminster Publications, Inc.. - 0003-3197 .- 1940-1574. ; 42:10, s. 836-842
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The rheologic properties of blood were studied in 6 patients with primary pulmonary hypertension (PPH) and compared with those of a control group of 10 healthy subjects. Blood viscosity was studied with a rotational viscometer and blood cell deformability with a filtrometer giving values for clogging particles (CP) and red cell transit time (RCTT). Blood viscosity at varying shear rates was found to be increased both at natural (p<0.025-0.005) and standardized hematocrit, 45% (p<0.05 at 40 s-1) in patients with PPH. Red cell deformability was reduced as indicated by a significant increase of RCTT (p<0.01). Increased values for hematocrit (p<0.001), hemoglobin concentration (p< 0.001), and erythrocyte count (p<0.005) were found and decreased values for mean corpuscular hemoglobin concentration (MCHC) (p< 0.025) and HDL cholesterol (p<0.005). Plasma viscosity, white cell deformability, white cell count, mean corpuscular volume (MCV), and plasma fibrinogen concentration did not significantly differ from the values found in the control group. It is concluded that patients with PPH have impaired blood rheology. The hemorheologic abnormalities in these patients may be of hemodynamic significance.
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| 40. |
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