| 61. |
- Björk, Mikael, et al.
(författare)
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One-dimensional heterostructures in semiconductor nanowhiskers
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:6, s. 1058-1060
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Tidskriftsartikel (refereegranskat)abstract
- We report on the growth of designed heterostructures placed within semiconductor nanowhiskers, exemplified by the InAs/InP material system. Based on transmission electron microscopy, we deduce the interfaces between InAs and InP to be atomically sharp. Electrical measurements of thermionic emission across an 80-nm-wide InP heterobarrier, positioned inside InAs whiskers 40 nm in diameter, yield a barrier height of 0.6 eV. On the basis of these results, we propose new branches of physics phenomena as well as new families of device structures that will now be possible to realize and explore.
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| 62. |
- Björk, Mikael, et al.
(författare)
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One-dimensional steeplechase for electrons realized
- 2002
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 2:2, s. 87-89
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Tidskriftsartikel (refereegranskat)abstract
- We report growth of one-dimensional semiconductor nanocrystals, nanowhiskers, in which segments of the whisker with different composition are formed, illustrated by InAs whiskers containing segments of InP. Our conditions for growth allow the formation of abrupt interfaces and heterostructure barriers of thickness from a few monolayers to 100s of nanometers, thus creating a one-dimensional landscape along which the electrons move. The crystalline perfection, the quality of the interfaces, and the variation in the lattice constant are demonstrated by high-resolution transmission electron microscopy, and the conduction band off-set of 0.6 eV is deduced from the current due to thermal excitation of electrons over an InP barrier.
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| 63. |
- Bohlooly-Yeganeh, Mohammad, 1966, et al.
(författare)
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Enhanced spontaneous locomotor activity in bovine GH transgenic mice involves peripheral mechanisms
- 2001
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Ingår i: Endocrinology. ; 142:10, s. 4560-4567
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Tidskriftsartikel (refereegranskat)abstract
- Clinical and experimental studies indicate a role for GH in mechanisms related to anhedonia/hedonia, psychic energy, and reward. Recently we showed that transgenic mice with general overexpression of bovine GH display increased spontaneous locomotor activity. In the present study, we investigated whether this behavioral change is owing to a direct action of GH in the central nervous system or to peripheral GH actions. A transgenic construct, containing the glial fibrillary acidic protein promoter directing specific expression of bovine GH to the central nervous system, was designed. The central nervous system-specific expression of bovine GH in the glial fibrillary acidic protein-bovine GH transgenic mice was confirmed, but no effect on spontaneous locomotor activity was observed. Serum bovine GH levels were increased in glial fibrillary acidic protein-bovine GH transgenic mice but clearly lower than in transgenic mice with general overexpression of bovine GH. In contrast to the transgenic mice with general overexpression of bovine GH, glial fibrillary acidic protein-bovine GH mice did not display any difference in serum IGF-I levels. The levels of free T(3) and the conversion of the free T(4) to free T(3) were only increased in transgenic mice with general overexpression of bovine GH, but serum corticosterone levels were similarly increased in both transgenic models. These results suggest that free T(3) and/or IGF-I, affecting dopamine and serotonin systems in the central nervous system, may mediate the enhanced locomotor activity observed in transgenic mice with general overexpression of bovine GH.
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| 64. |
- Bohlooly-Yeganeh, Mohammad, 1966, et al.
(författare)
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Growth hormone overexpression in the central nervous system results in hyperphagia-induced obesity associated with insulin resistance and dyslipidemia.
- 2005
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Ingår i: Diabetes. - 0012-1797 .- 1939-327X. ; 54:1, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that peripherally administered growth hormone (GH) results in decreased body fat mass. However, GH-deficient patients increase their food intake when substituted with GH, suggesting that GH also has an appetite stimulating effect. Transgenic mice with an overexpression of bovine GH in the central nervous system (CNS) were created to investigate the role of GH in CNS. This study shows that overexpression of GH in the CNS differentiates the effect of GH on body fat mass from that on appetite. The transgenic mice were not GH-deficient but were obese and showed increased food intake as well as increased hypothalamic expression of agouti-related protein and neuropeptide Y. GH also had an acute effect on food intake following intracerebroventricular injection of C57BL/6 mice. The transgenic mice were severely hyperinsulinemic and showed a marked hyperplasia of the islets of Langerhans. In addition, the transgenic mice displayed alterations in serum lipid and lipoprotein levels and hepatic gene expression. In conclusion, GH overexpression in the CNS results in hyperphagia-induced obesity indicating a dual effect of GH with a central stimulation of appetite and a peripheral lipolytic effect.
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| 65. |
- Bohlooly-Yeganeh, Mohammad, 1966, et al.
(författare)
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Osteoporosis in MCHR1-deficient mice.
- 2004
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Ingår i: Biochemical and biophysical research communications. - : Elsevier BV. - 0006-291X. ; 318:4, s. 964-9
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Tidskriftsartikel (refereegranskat)abstract
- It is well recognized that the hypothalamus is of central importance in the regulation of food intake and fat mass. Recent studies indicate that it also plays an important role in the regulation of bone mass. Melanin concentrating hormone (MCH) is highly expressed in the hypothalamus and has been implicated in regulation of energy homeostasis. We developed MCHR1 inactivated mice to evaluate the physiological role of this receptor. Interestingly, the MCHR1(-/-) mice have osteoporosis, caused by a reduction in the cortical bone mass, while the amount of trabecular bone is unaffected. The reduction in cortical bone mass is due to decreased cortical thickness. Serum levels of c-telopeptide, a marker of bone resorption, are increased in MCHR1(-/-) mice, indicating that the MCHR1(-/-) mice have a high bone turnover osteoporosis. In conclusion, the MCHR1(-/-) mice have osteoporosis, indicating that MCHR1-signalling is involved in a tonic stimulation of bone mass.
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| 66. |
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| 67. |
- Bokrantz, Tove, et al.
(författare)
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The association between peripheral arterial disease and risk for hip fractures in elderly men is not explained by low hip bone mineral density. Results from the MrOS Sweden study
- 2022
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 33, s. 2607-2617
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Tidskriftsartikel (refereegranskat)abstract
- In this prospective study in Swedish elderly men, PAD based on an ABI < 0.9 was associated with an increased risk of hip fracture, independent of age and hip BMD. However, after further adjustments for comorbidity, medications, physical function, and socioeconomic factors, the association diminished and was no longer statistically significant. Introduction To examine if peripheral arterial disease (PAD) is associated with an increased risk for hip fracture in men independent of hip BMD. Methods Ankle-brachial index (ABI) was assessed in the Swedish MrOS (Osteoporotic Fractures in Men) study, a prospective observational study including 3014 men aged 69-81 years at baseline. PAD was defined as ABI < 0.90. Incident fractures were assessed in computerized X-ray archives. The risk for hip fractures was calculated using Cox proportional hazard models. At baseline, BMD was assessed using DXA (Lunar Prodigy and Hologic QDR 4500) and functional measurements and blood samples were collected. Standardized questionnaires were used to collect information about medical history, falls, and medication. Results During 10 years of follow-up, 186 men had an incident hip fracture. The hazard ratio (HR) for hip fracture in men with PAD was 1.70 (95% CI 1.14-2.54), adjusted for age and study site. Additional adjustment for total hip BMD marginally affected this association (HR 1.64; 95% CI 1.10-2.45). In a final multivariate model, the HR attenuated to a non-significant HR 1.38 (95% CI 0.91-2.11) adjusted for age, site, hip BMD, BMI, falls, smoking, eGFR, handgrip strength, walking speed, former hip fracture, antihypertensive treatment, diabetes, education, and history of cardiovascular disease. Conclusion This study suggests that PAD is associated with an increased risk for hip fracture independently of hip BMD in elderly Swedish men. However, the high frequency of comorbidity and lower physical performance among men with PAD might partly explain this association.
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| 68. |
- Botusan, I. R., et al.
(författare)
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Deficiency of liver-derived insulin-like growth factor-I (IGF-I) does not interfere with the skin wound healing rate
- 2018
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Objective: IGF-I is a growth factor, which is expressed in virtually all tissues. The circulating IGF-I is however derived mainly from the liver. IGF-I promotes wound healing and its levels are decreased in wounds with low regenerative potential such as diabetic wounds. However, the contribution of circulating IGF-I to wound healing is unknown. Here we investigated the role of systemic IGF-I on wound healing rate in mice with deficiency of liver-derived IGF-I (LI-IGF-I-/- mice) during normal (normoglycemic) and impaired wound healing (diabetes). Methods: LI-IGF-I-/- mice with complete inactivation of the IGF-I gene in the hepatocytes were generated using the Cre/loxP recombination system. This resulted in a 75% reduction of circulating IGF-I. Diabetes was induced with streptozocin in both LI-IGF-I-/- and control mice. Wounds were made on the dorsum of the mice, and the wound healing rate and histology were evaluated. Serum IGF-I and GH were measured by RIA and ELISA respectively. The expression of IGF-I, IGF-II and the IGF-I receptor in the skin were evaluated by qRT-PCR. The local IGF-I protein expression in different cell types of the wounds during wound healing process was analyzed using immunohistochemistry. Results: The wound healing rate was similar in LI-IGF-I-/- mice to that in controls. Diabetes significantly delayed the wound healing rate in both LI-IGF-I-/- and control mice. However, no significant difference was observed between diabetic animals with normal or reduced hepatic IGF-I production. The gene expression of IGF-I, IGF-II and IGF-I receptor in skin was not different between any group of animals tested. Local IGF-I levels in the wounds were similar between of LI-IGF-I-/- and WT mice although a transient reduction of IGF-I expression in leukocytes in the wounds of LI-IGF-I-/- was observed seven days post wounding. Conclusion: Deficiency in the liver-derived IGF-I does not affect wound healing in mice, neither in normo-glycemic conditions nor in diabetes.
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| 69. |
- Bramsved, Rebecka, 1982, et al.
(författare)
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Birth Weight, Childhood and Young Adult Overweight, and the Risk of Coronary Heart Disease in Men.
- 2024
-
Ingår i: Arteriosclerosis, thrombosis, and vascular biology. - 1524-4636. ; 44:1, s. 314-321
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Tidskriftsartikel (refereegranskat)abstract
- Low birth weight is a known risk factor for adult coronary heart disease (CHD), but the additional effect of weight development during childhood and early adult life has not been studied.We included 35659 men born 1945 to 1961 from the population-based BMI Epidemiology Study Gothenburg, with data available on birthweight, BMI in childhood (8 years), and BMI in young adulthood (20 years). Information on CHD diagnoses was retrieved from national registers. We used Cox proportional hazards regression to estimate hazard ratios and 95% CIs for the risk of early and late CHD (before and after 58.4 years of age, respectively).During follow-up, a total of 3380 cases of CHD (fatal and nonfatal) were registered. Birth weight was inversely associated with the risk of both early (hazard ratio, 0.88 per SD increase [95% CI, 0.84-0.92]) and late (hazard ratio, 0.94 per SD increase [95% CI, 0.90-0.98]) CHD, independently of BMI at 8 years and BMI change during puberty. In a model including birth weight (below or above the median) together with overweight at 8 and 20 years, only birth weight and young adult overweight, but not overweight in childhood, were significantly associated with the risk of CHD. A birth weight below the median, followed by overweight at 20 years of age was associated with a more than doubled risk of early CHD (hazard ratio, 2.29 [95% CI, 1.86-2.81]), compared with the reference (birth weight above the median and normal weight at 20 years of age). This excess risk was even more pronounced for a birthweight below 2.5 kg.We demonstrate that low birth weight and young adult overweight are important developmental markers of risk for adult CHD. These findings motivate a life course perspective for prevention and risk assessment of adult CHD.
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| 70. |
- Brembeck, Petra, 1977, et al.
(författare)
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Changes in cortical volumetric bone mineral density and thickness, and trabecular thickness in lactating women postpartum.
- 2015
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 100:2, s. 535-543
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Tidskriftsartikel (refereegranskat)abstract
- Context: Lactation is associated with decreased areal bone mineral density (aBMD). Replenishment occurs especially after ceased lactation. Changes in volumetric BMD (vBMD), microstructure and dimensional parameters are unknown and may clarify the role of lactation for skeletal health. Objective: and main outcomes: To test the hypothesis that lactation is associated with changes in aBMD, vBMD, microstructure and dimensional parameters. Design: At baseline (0.5 months after delivery) and 4, 12 and 18 months thereafter bone was assessed using dual energy x-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT). Participants: and setting: Eighty-one fair-skinned postpartum women and 21 controls aged 25-40 years were recruited. Completion ratio was 73%. Postpartum women were categorized depending on duration of lactation; 0-3.9, 4-8.9 and ≥9 months. Results: During the first 4 months, aBMD decreased at several sites (geometric mean±SE; -0.73±0.21% to -3.98±0.76%) in women lactating at least 4 months. During the same time, cortical vBMD at ultra-distal tibia decreased in women lactating 4-8.9 months (-0.26±0.08%) and ≥9 months (-0.49±0.10%). At 12 months postpartum, also cortical thickness (≥9 months, -2.48±0.41%) and trabecular thickness (4-8.9 months, -2.14±0.92%; ≥9 months, -2.56±1.21%) were lower than baseline. No decreases were found in women lactating less than 4 months or in controls in these parameters. At 18 months postpartum, both cortical vBMD (≥9 months, -0.77±0.17%) and trabecular thickness (4-8.9 months, -2.25±1.25%; ≥9 months, -3.21±1.41%) were lower in women with long lactation. Conclusions: Decreases in cortical vBMD, thickness, and trabecular thickness at ultra-distal tibia were found in women lactating 4 months or longer. Longer follow-up is needed to confirm whether women with extended lactation recover fully, or whether the changes could potentially lead to increased risk of fracture in later life.
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