| 1. |
- Almqvist, E, et al.
(författare)
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Ancestral differences in the distribution of the delta 2642 glutamic acid polymorphism is associated with varying CAG repeat lengths on normal chromosomes : insights into the genetic evolution of Huntington disease.
- 1995
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 4:2, s. 207-14
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Tidskriftsartikel (refereegranskat)abstract
- This study addresses genetic factors associated with normal variation of the CAG repeat in the Huntington disease (HD) gene. To achieve this, we have studied patterns of variation of three trinucleotide repeats in the HD gene including the CAG and adjacent CCG repeats as well as a GAG polymorphism at residue 2642 (delta 2642). We have previously demonstrated that variation in the CCG repeat is associated with variation of the CAG repeat length on normal chromosomes. Here we show that differences in the GAG trinucleotide polymorphism at residue 2642 is also significantly correlated with CAG size on normal chromosomes. The B allele which is associated with higher CAG repeat lengths on normal chromosomes is markedly enriched on affected chromosomes. Furthermore, this glutamic acid polymorphism shows significant variation in different ancestries and is absent in chromosomes of Japanese, Black and Chinese descent. Haplotype analysis of both the CCG and delta 2642 polymorphisms have indicated that both are independently associated with differences in CAG length on normal chromosomes. These findings lead to a model for the genetic evolution of new mutations for HD preferentially occurring on normal chromosomes with higher CAG repeat lengths and a CCG repeat length of seven and/or a deletion of the glutamic acid residue at delta 2642. This study also provides additional evidence for genetic contributions to demographic differences in prevalence rates for HD.
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| 2. |
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| 3. |
- Cresswell, Andrew G, et al.
(författare)
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Influence of gastrocnemius muscle length on triceps surae torque development and electromyographic activity in man.
- 1995
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 105:2, s. 283-90
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Tidskriftsartikel (refereegranskat)abstract
- The present study was designed to determine the relative contribution of the gastrocnemius muscle to isometric plantar flexor torque production at varying knee angles, while investigating the activation of the gastrocnemius muscle at standardised non-optimal lengths. Voluntary plantar flexor torque, supramaximally stimulated twitch torque and myoelectric activity (EMG) from the triceps surae were measured at different knee angles. Surface and intra-muscular EMG were recorded from the soleus muscle and the medial and lateral heads of the gastrocnemius muscle in 10 male subjects. With the ankle angle held constant, knee angle was changed in steps of 30 degrees ranging from 180 degrees (extended) to 60 degrees (extreme flexion), while voluntary torque from a 5-s contraction was determined at 10 different levels of voluntary effort, ranging from 10% of maximal effort to maximal effort. To assess effort, supramaximal twitches were superimposed on all voluntary contractions, and additionally during rest. Maximal plantar flexor torque and resting twitch torque decreased significantly in a sigmoidal fashion with increasing knee flexion to 60% of the maximum torque at 180 degrees knee angle. For similar levels of voluntary effort, the EMG root mean square (RMS) of gastrocnemius was less with increased knee flexion, whereas soleus RMS remained unchanged. From these data, it is concluded that the contribution of gastrocnemius to plantar flexor torque is at least 40% of the total torque in the straight leg position. The decrease of gastrocnemius EMG RMS with decreasing muscle length may be brought about by a decrease in the number of fibres within the EMG electrode recording volume and/or impaired neuromuscular transmission.
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| 4. |
- Hansen, G, et al.
(författare)
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Retningslinjer for utredning og behandling av kronisk obstruktiv lungesykdom
- 1995
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Ingår i: Tidsskrift for Den Norske Lægeforening. - 0029-2001. ; 115:6, s. 710-713
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Tidskriftsartikel (refereegranskat)abstract
- A group of chest physicians, general practitioners, clinical pharmacologist and pharmacists appointed by the Institute of Pharmacotherapy, University of Oslo has evaluated the present knowledge about treatment of chronic obstructive lung disease. The group discusses today's medical treatment of this rather numerous group of patients. It is stated that, to a high degree, the treatment of these patients lacks proper documentation, and that treatment needs to be tested out on an individual basis. The group proposes a flow chart for this purpose.
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| 5. |
- Heimann, Mikael, 1951-, et al.
(författare)
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Deferred imitation in 9- and 14- months old Infants: A longitudinal study of a Swedish sample
- 1996
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Ingår i: British Journal of Developmental Psychology. - 0261-510X .- 2044-835X. ; 14, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated deferred imitation using a longitudinal design. A total of 62Swedish children (32 girls) were tested at both 9 and 14 months of age. The memorydelay interval was 10 minutes at 9 months and five minutes at 14 months of age. Atboth ages children in the imitation group displayed significantly more target actionsafter modelling than the children in the control group, thus replicating earlierreports of imitation from memory. It was found that individual children with atendency to perform low deferred imitation at 9 months of age tended to remain lowon the test at 14 months, thus raising the possibility of stable individual differencesin imitation. This study provides a first investigation of deferred imitationlongitudinally among young children, and supports recent theoretical claims thatdeferred imitation arises earlier in ontogeny than was hypothesized by classicaltheory. It was observed that there are cultural differences in the way that Swedishversus American adult-infant pairs act in the test situation and ideas are offeredregarding the roots of such differences.
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| 6. |
- Lindström, Sofie, et al.
(författare)
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Intraspecific variation of taeniate bisaccate pollen within permian glossopterid sporangia, from the Prince Charles Mountains, Antarctica
- 1997
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Ingår i: International Journal of Plant Sciences. - 1058-5893. ; 158:5, s. 673-684
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Tidskriftsartikel (refereegranskat)abstract
- Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf A. africana Pant ana Nautiyal. These sporangia contain between 2000 and 3000 taeniate, saccate pollen grains that are predominantly haploxylonoid bisaccate and referable to the palynotaxon Protohaploxypinus limpidus (Balme and Hennelly) Balme and Flayford. However, the sporangia also contain greater than 4% of diploxylonoid bisaccate forms comparable to Striatopodocarpidites cancellatus (Balme and Hennelly) Hart 1963, together with sporadic monosaccate and trisaccate grains that, if found dispersed, would be assigned to several different pollen form genera. Morphometric analysis of in situ bisaccate pollen grains and taeniate bisaccate pollen in the dispersed palynoflora indicates that in situ grains occupy only the smaller end of the total size range. The tendency for in situ grains to cluster into two different size groups may reflect differential predispersal expansion of the corpus. The in situ pollen grains are variable in most qualitative and quantitative features used for taxonomic discrimination of dispersed taeniate bisaccate pollen, and this may lead to unreliable estimates of Late Permian floristic diversity if an overly restrictive species delimitation scheme is used.
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| 7. |
- Löscher, W N, et al.
(författare)
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Central fatigue during a long-lasting submaximal contraction of the triceps surae.
- 1996
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 108:2, s. 305-14
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Tidskriftsartikel (refereegranskat)abstract
- Our purpose was to study central fatigue and its dependence on peripheral reflex inhibition during a sustained submaximal contraction of the triceps surae. In 11 healthy subjects, superimposed twitches, surface electromyograms (EMG) from the medial head of the gastrocnemius (MG) and soleus (SOL) muscles, maximal compound motor action potentials (M(max)), tracking error and tremor were recorded during sustained fatiguing contractions at a torque level corresponding to 30% of maximal voluntary contraction (MVC). When the endurance limit (401 +/- 91 s) of the voluntary contraction (VC-I) was reached, the triceps surae could be electrically stimulated to the same torque level for an additional 1 min in 10 of the 11 subjects. These subjects were then able to continue the contraction voluntarily (voluntary contraction II, VC-II) for another 85 +/- 48 s. At the endurance limit of VC-I, the superimposed twitch was larger than during the unfatigued MVC, while there was no significant difference between the twitch at the endurance limit of VC-II and MVC. The EMG amplitude of both MG and SOL at the endurance limit of VC-I was significantly less than that during the MVC. While the EMG amplitude of MG increased further during VC-II, SOL EMG remained unchanged, neither muscle reaching their unfatigued MVC values. This difference was diminished for SOL by taking into account its decrease in M(max) found during VC-II, and relative EMG levels approached their MVC values. These results clearly indicate that a higher voluntary muscle activation was achievable after 1 min of electrical muscle stimulation, which continued metabolic stress and contractile fatigue processes but allowed for supraspinal, muscle spindle and/or motoneuronal recovery. It is concluded that peripheral reflex inhibition of alpha-motoneurons via small-diameter muscle afferents is of minor significance for the development of the central fatigue that was found to occur during the first voluntary contraction.
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| 8. |
- Löscher, W N, et al.
(författare)
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Excitatory drive to the alpha-motoneuron pool during a fatiguing submaximal contraction in man.
- 1996
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 491 ( Pt 1), s. 271-80
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Tidskriftsartikel (refereegranskat)abstract
- 1. This study was undertaken to examine changes of excitatory drive to the triceps surae alpha-motoneuron pool during fatiguing submaximal isometric contractions in man. Eight healthy subjects maintained isometric plantar flexions at 30 percent of maximum voluntary contraction (MVC) until the limit of endurance (range, 6-9 min). 2. Excitability of the alpha-motoneuron pool to Ia afferent stimulation (H reflex), electromyograms (EMG) and maximum compound motor unit action potentials (Mmax) from the lateral (LG) and medial heads (MG) of the gastrocnemius as well as from the soleus muscle (Sol) were recorded throughout the contraction. Superimposed maximum twitch torques (twitch occlusion) and isometric torque fluctuations (tremor) were also recorded as indirect measures of excitatory drive. 3. H reflexes were studied at different levels of underlying voluntary contraction to assess the relationship between H reflex amplitude and excitatory drive. With increasing levels of underlying contraction up to MVC, superimposed H reflex amplitude increased for LG in six subjects, for MG in all eight and for Sol in five. In the remaining cases, H reflex amplitude first increased and then plateaued between 30-50% of MVC. 4. H/Mmax ratios increased during fatigue in those muscles that showed an H reflex amplitude increase with high levels of underlying contraction. In these cases, LG and MG H/Mmax increased significantly after about 50 and 20% of endurance time onward, respectively, whereas Sol H/Mmax demonstrated a significant increase up to 40% of endurance time. 5. EMG root mean square (r.m.s.) increased linearly throughout the contraction for all three muscles, while tremor r.m.s. increased in a non-linear way, with a steeper increase from 60% of endurance time onward. Superimposed twitch amplitude decreased significantly from 25% of endurance time onward. 6. It is concluded that during fatiguing isometric contractions at 30% of MVC, the excitatory drive to the triceps surae alpha-motoneuron pool increases. This is thought to be a compensatory mechanism to facilitate recruitment of new, unfatigued motor units (MUs), and/or to increase MU firing rates. The facts that the twitch is not abolished at endurance limit and that the EMG does not attain its unfatigued MVC level are strong indications that central fatigue occurred during the sustained submaximal contraction.
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| 9. |
- McLoughlin, Stephen, et al.
(författare)
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Gondwanan floristic and sedimentological trends during the Permian-Triassic transition: new evidence from the Amery Group, northern Prince Charles Mountains, East Antarctica
- 1997
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Ingår i: Antarctic Science. - 1365-2079. ; 9:3, s. 281-298
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Tidskriftsartikel (refereegranskat)abstract
- The Permian-Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the Bainmedart Coal Measures and overlying Flagstone Bench Formation, based on the first regular occurrence of Lunatisporites pellucidus and the first appearance of Aratrisporites and Lepidopteris species. The Permian-Triassic boundary is marked by the extinction of glossopterid and cordaitalean gymnosperms, and by the disappearance or extreme decline of a range of gymnospermous and pteridophytic palynomorph groups. Earliest Triassic macrofloras and palynofloras of the Flagstone Bench Formation are dominated by peltasperms and lycophytes; corystosperms, conifers, and ferns become increasingly common elements of assemblages through the Lower Triassic part of the formation and dominate floras of the Upper Triassic strata. The sedimentary transition across this boundary is conformable but marked by a termination of coal deposits; overlying lowermost Triassic sediments contain only carbonaceous siltstones. Typical red-bed facies are not developed until at least 100 m above the base of the Flagstone Bench Formation, in strata containing ?Middle Triassic palynofloras. Across Gondwana the diachronous disappearance of coal deposits and appearance of red-beds is suggestive of a response to shifting climatic belts, resulting in progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic. The abrupt and approximately synchronous replacement of plant groups at the Permian-Triassic boundary suggests that factors independent of, or additional to, climate change were responsible for the turnover in terrestrial floras.
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| 10. |
- Zabel, B A, et al.
(författare)
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Human G protein-coupled receptor GPR-9-6/CC chemokine receptor 9 is selectively expressed on intestinal homing T lymphocytes, mucosal lymphocytes, and thymocytes and is required for thymus-expressed chemokine-mediated chemotaxis
- 1999
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Ingår i: Journal of Experimental Medicine. - 1540-9538. ; 190:9, s. 1241-1256
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Tidskriftsartikel (refereegranskat)abstract
- TECK (thymus-expressed chemokine), a recently described CC chemokine expressed in thymus and small intestine, was found to mediate chemotaxis of human G protein-coupled receptor GPR-9-6/L1.2 transfectants. This activity was blocked by anti-GPR-9-6 monoclonal antibody (mAb) 3C3. GPR-9-6 is expressed on a subset of memory alpha4beta7(high) intestinal trafficking CD4 and CD8 lymphocytes. In addition, all intestinal lamina propria and intraepithelial lymphocytes express GPR-9-6. In contrast, GPR-9-6 is not displayed on cutaneous lymphocyte antigen-positive (CLA(+)) memory CD4 and CD8 lymphocytes, which traffic to skin inflammatory sites, or on other systemic alpha4beta7(-)CLA(-) memory CD4/CD8 lymphocytes. The majority of thymocytes also express GPR-9-6, but natural killer cells, monocytes, eosinophils, basophils, and neutrophils are GPR-9-6 negative. Transcripts of GPR-9-6 and TECK are present in both small intestine and thymus. Importantly, the expression profile of GPR-9-6 correlates with migration to TECK of blood T lymphocytes and thymocytes. As migration of these cells is blocked by anti-GPR-9-6 mAb 3C3, we conclude that GPR-9-6 is the principal chemokine receptor for TECK. In agreement with the nomenclature rules for chemokine receptors, we propose the designation CCR-9 for GPR-9-6. The selective expression of TECK and GPR-9-6 in thymus and small intestine implies a dual role for GPR-9-6/CCR-9, both in T cell development and the mucosal immune response.
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