| 31. |
- Jenni, L, et al.
(författare)
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Effect of endurance flight on haematocrit in migrating birds
- 2006
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Ingår i: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7192 .- 2193-7206. ; 147:4, s. 531-542
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The effects of an endurance flight on the haematocrit, the percentage of packed red blood cells per blood volume, were examined within the framework of six possible factors explaining possible changes in the haematocrit. Two approaches were adopted: (1) the haematocrit was studied in four species of passerine birds which landed on an Italian island after having crossed the Mediterranean Sea on their spring migration in a non-stop flight; (2) the haematocrit was evaluated in six individual red knots after a flight of 1, 2, 4 and 10 h in a wind tunnel and the data thus obtained compared with data on resting birds with or without food. In the four passerine species, the haematocrit decreased from 51% in fat birds to 48% in lean birds. In lean birds, the haematocrit dropped from 48% in birds with well-developed breast muscles to 36% in birds with emaciated breast muscles. In the red knots, the haematocrit was dependent on body mass in flying and resting birds. The haematocrit decreased from about 51% pre-flight to about 49% within 1 h of flight and remained at this level for up to 10 h of flight. Taking the results from the passerines and the red knots together, it seems that the haematocrit drops by a few percentage points within 1 h after the onset of flight, decreases very slowly with decreasing body mass and decreases more steeply in very lean birds having entered stage III of fasting. This indicates that dehydration is not an underlying factor in decreased haematocrit because if this were the case we would expect an increase with endurance flight. We found no effect of the presence of blood parasites on haematocrit. With the onset of flight, haemodilution may be adaptive, because it reduces blood viscosity and, thereby, energy expenditure by the heart, or it may be a sign of water conservation as an insurance against the risk of dehydration during long non-stop flights. During endurance flight, a reduction in the haematocrit may be adaptive, in that oxygen delivery capacity is adjusted to the decreased oxygen needs as body mass decreases. A decreasing haematocrit would also allow birds to reduce heart beat frequency and/or heart size, because blood viscosity decreases disproportionally with decreasing haematocrit. However, when energy stores are about to come to an end and birds increase protein breakdown, the haematocrit decreases even further, and birds probably become anaemic due to a reduced erythropoiesis.
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| 32. |
- Kiiski, Johanna I., et al.
(författare)
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FANCM mutation c.5791C>T is a risk factor for triple-negative breast cancer in the Finnish population
- 2017
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Ingår i: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 0167-6806 .- 1573-7217. ; 166:1, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The FANCM c.5101C>T nonsense mutation was previously found to associate with breast cancer in the Finnish population, especially among triple-negative cases. Here, we studied the prevalence of three other FANCM variants: c.5791C>T, which has been reported to predispose to familial breast cancer, and the c.4025_4026delCT and c.5293dupA variants recently identified in Finnish cancer patients. Methods: We genotyped the FANCM c.5791C>T mutation in 4806 invasive breast cancer patients, including BRCA1/2 mutation negative familial cases and unselected cases, and in 2734 healthy population controls from four different geographical areas of Finland. The association of the mutation with breast cancer risk among patient subgroups was statistically evaluated. We further analyzed the combined risk associated with c.5101C>T and c.5791C>T mutations. We also genotyped 526 unselected ovarian cancer patients for the c.5791C>T mutation and 862 familial breast cancer patients for the c.4025_4026delCT and c.5293dupA variants. Results: The frequency of the FANCM c.5791C>T mutation was higher among breast cancer cases than in controls (OR 1.94, 95% CI 0.87–4.32, P = 0.11), with a statistically significant association with triple-negative breast cancer (OR 5.14, 95% CI 1.65–16.0, P = 0.005). The combined analysis for c.5101C>T and c.5791C>T carriers confirmed a strong association with breast cancer (OR 1.86, 95% CI 1.32–2.49, P = 0.0002), especially among the triple-negative patients (OR 3.08, 95% CI 1.77–5.35, P = 0.00007). For the other variants, only one additional c.4025_4026delCT carrier and no c.5293dupA carriers were observed. Conclusions: These results support the role of FANCM as a breast cancer susceptibility gene, particularly for triple-negative breast cancer.
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| 33. |
- Klaassen, M, et al.
(författare)
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Flight costs and fuel composition of a bird migrating in a wind tunnel
- 2000
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Ingår i: The Condor: ornithological applications. - 0010-5422. ; 102:2, s. 444-451
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Tidskriftsartikel (refereegranskat)abstract
- We studied the energy and protein balance of a Thrush Nightingale Luscinia luscinia, a small long-distance migrant, during repeated 12-hr long Eights in a wind tunnel and during subsequent two-day fueling periods. From the energy budgets we estimated the power requirements for migratory flight in this 26 g bird at 1.91 Watts. This is low compared to flight cost estimates in birds of similar mass and with similar wing shape. This suggests that power requirements for migratory flight are lower than the power requirements for nonmigratory Eight. From excreta production during Right, and nitrogen and energy balance during subsequent fueling, the dry protein proportion of stores was estimated to be around 10%. A net catabolism of protein during migratory flight along with that of fat may reflect a physiologically inevitable process, a means of providing extra water to counteract dehydration, a production of uric acid for anti-oxidative purposes, and adaptive changes in the size of Eight muscles and digestive organs in the exercising animal.
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| 34. |
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| 35. |
- Kvist, Anders, 1961
(författare)
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Atom Probe Field Ion Microscopy of Surface Zones, Coatings and Interfaces
- 1995
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on developingmethods for high resolution microanalysis of coatings on a substrate, andsurface zones of a bulk sample using atom probe field ion microscopy,APFIM. The APFIM technique is described and some examples of its applications to semiconductors,cemented carbides and intermetallic compounds are given. The main part of the thesis is concerned with the formation of Schottky andohmic contacts on highly-doped GaAs. Three different metal coatings wereanalysed, gold, silver and gold-germanium, all of them formed on an APFIMspecimen of the semiconductor. The gold and silver coatings were studied on atomically clean as well asair exposed GaAs surfaces. Intermixing occurred for Au on a clean surfacewhereas Ag showed an atomically abrupt interface. Oxygen seemed to stopintermixing between Au and GaAs, but promoted diffusion of Ag into the semiconductor. Deposition of thegold-germanium alloy was only made on oxidised GaAs surfaces and the effectof heat treatment on this contact was studied. After heat treatment a thinlayer containing a few at.% of Ge in the GaAs was observed beneath an almost pure layer of Au. A technique for preparing APFIM specimens of the near surface zone of acemented carbide sample was developed, using a combination of dimplegrinding, electropolishing and ion milling. The first results obtained froma specimen prepared with this methodare presented. The possible applicability of this technique to metal/GaAsinterfaces and CVD-coated cemented carbides is discussed. APFIM analysis for the determination of the platinum distribution in anordered Cu3Au(4 at.% Pt) alloy is presented with a particularinterest in problems related to quantitative analysis near and at grainboundaries.
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| 36. |
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| 37. |
- Kvist, Anders, et al.
(författare)
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Basal metabolic rate in migratory waders: intra-individual, intraspecific, interspecific and seasonal variation
- 2001
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Ingår i: Functional Ecology. - : Wiley. - 1365-2435 .- 0269-8463. ; 15:4, s. 465-473
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Tidskriftsartikel (refereegranskat)abstract
- 1. Basal metabolic rates (BMR) were measured in 36 adult and 119 juvenile waders of 19 species on autumn migration in southern Sweden. 2. Ina comparison with literature data, it was found that juvenile BMR was generally lower than at the onset of migration in the Arctic and slightly higher than on African wintering grounds. 3. The seasonal differences may reflect local physiological adaptations or possibly a gradual decline from high premigratory levels due to growth. Our data contradict the idea that BMR is high during migration as an adaptation to generally high levels of energy expenditure. 4. The allometric exponent, scaling BMR to body mass, was significantly higher within individuals (1.19) and within species (1.82) than among species (0.62). 5. The high intra-individual exponent indicates that non-fat tissues, with a high metabolic activity, are involved in the mass changes during migratory stopover. 6. The high intraspecific exponent indicates that tissues with a high metabolic activity contributed disproportionately to variation in body mass among individuals or that larger individuals had elevated mass specific metabolic rates of some tissues.
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| 38. |
- Kvist, Anders, et al.
(författare)
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Carrying large fuel loads during sustained bird flight is cheaper than expected
- 2001
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 413:6857, s. 730-732
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Tidskriftsartikel (refereegranskat)abstract
- Birds on migration alternate between consuming fuel stores during flights and accumulating fuel stores during stopovers. The optimal timing and length of flights and stopovers for successful migration depend heavily on the extra metabolic power input (fuel use) required to carry the fuel stores during flight(1,2). The effect of large fuel loads on metabolic power input has never been empirically determined. We measured the total metabolic power input of a long-distance migrant, the red knot (Calidris canutus), flying for 6 to 10 h in a wind tunnel, using the doubly labelled water technique(3). Here we show that total metabolic power input increased with fuel load, but proportionally less than the predicted mechanical power output from the flight muscles. The most likely explanation is that the efficiency with which metabolic power input is converted into mechanical output by the flight muscles increases with fuel load. This will influence current models of bird flight and bird migration. It may also help to explain why some shorebirds, despite the high metabolic power input required to fly, routinely make nonstop flights of 4,000 km longer(4).
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| 39. |
- Kvist, Alexander, et al.
(författare)
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Chondroitin sulfate perlecan enhances collagen fibril formation - Implications for perlecan chondrodysplasias
- 2006
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 281:44, s. 33127-33139
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Tidskriftsartikel (refereegranskat)abstract
- Inactivation of the perlecan gene leads to perinatal lethal chondrodysplasia. The similarity to the phenotypes of the Col2A1 knock-out and the disproportionate micromelia mutation suggests perlecan involvement in cartilage collagen matrix assembly. We now present a mechanism for the defect in collagen type II fibril assembly by perlecan-null chondrocytes. Cartilage perlecan is a heparin sulfate or a mixed heparan sulfate/ chondroitin sulfate proteoglycan. The latter form binds collagen and accelerates fibril formation in vitro, with more defined fibril morphology and increased fibril diameters produced in the presence of perlecan. Interestingly, the enhancement of collagen fibril formation is independent on the core protein and is mimicked by chondroitin sulfate E but neither by chondroitin sulfate D nor dextran sulfate. Furthermore, perlecan chondroitin sulfate contains the 4,6-disulfated disaccharides typical for chondroitin sulfate E. Indeed, purified glycosaminoglycans from perlecan-enriched fractions of cartilage extracts contain elevated levels of 4,6-disulfated chondroitin sulfate disaccharides and enhance collagen fibril formation. The effect on collagen assembly is proportional to the content of the 4,6- disulfated disaccharide in the different cartilage extracts, with growth plate cartilage glycosaminoglycan being the most efficient enhancer. These findings demonstrate a role for perlecan chondroitin sulfate side chains in cartilage extracellular matrix assembly and provide an explanation for the perlecan-null chondrodysplasia.
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| 40. |
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