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  • Pundziute-Lycka, A, et al. (författare)
  • The incidence of Type I diabetes has not increased but shifted to a younger age at diagnosis in the 0-34 years group in Sweden 1983 to 1998
  • 2002
  • Ingår i: Diabetologia. - 0012-186X. ; 45:6, s. 783-791
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims/hypothesis. To analyse the incidence of Type I (insulin-dependent) diabetes mellitus in the 0-34 years age group in Sweden 1983-1998. Methods. Incidence and cumulative incidence per 100 000 and Poisson regression analysis of age-period effects was carried out using 11 751 cases from two nation-wide prospective registers. Results. Incidence (95%-CI) was 21.4 (20.8-21.9) in men and 17.1 (16.6-17.5) in women between 0 and 34 years of age. In boys aged 0-14 and girls aged 0-12 years the incidence increased over time, but it tended to decrease at older age groups, especially in men. Average cumulative incidence at 35 years was 748 in men and 598 in women. Cumulative incidence in men was rather stable during four 4-year periods (736, 732, 762, 756), while in women it varied more (592, 542, 617, 631). In males aged 0-34 years, the incidence did not vary between the 4-year periods (p=0.63), but time changes among the 3-year age groups differed (p<0.001). In females the incidence between the periods varied (p<0.001), being lower in 1987-1990 compared to 1983-1986, but time changes in the age groups did not differ (p=0.08). For both sexes median age at diagnosis was higher in 1983-1986 than in 1995-1998 (p<0.001) (15.0 and 12.5 years in males, 11.9 and 10.4 in females, respectively). Conclusion/interpretation. During a 16-year period the incidence of Type I diabetes did not increase in the 0-34 years age group in Sweden, while median age at diagnosis decreased. A shift to younger age at diagnosis seems to explain the increasing incidence of childhood Type I diabetes.
  • Jonsson, Isak, et al. (författare)
  • Recursive Blocked Algorithms for Solving Triangular Systems - Part I: : One-Sided and Coupled Sylvester-Type Matrix Equations
  • 2002
  • Ingår i: ACM Transactions on Mathematical Software. - 0098-3500 ; 28:4, s. 392-415
  • Tidskriftsartikel (refereegranskat)abstract
    • Triangular matrix equations appear naturally in estimating the condition numbers of matrix equations and different eigenspace computations, including block-diagonalization of matrices and matrix pairs and computation of functions of matrices. To solve a triangular matrix equation is also a major step in the classical Bartels-Stewart method for solving the standard continuous-time Sylvester equation (AX-XB=C). We present novel recursive blocked algorithms for solving one-sided triangular matrix equations, including the continuous-time Sylvester and Lyapunov equations, and a generalized coupled Sylvester equation. The main parts of the computations are performed as level-3 general matrix multiply and add (GEMM) operations. In contrast to explicit standard blocking techniques, our recursive approach leads to an automatic variable blocking that has the potential of matching the memory hierarchies of today's HPC systems. Different implementation issues are discussed, including when to terminate the recursion, the design of new optimized superscalar kernels for solving leaf-node triangular matrix equations efficiently, and how parallelism is utilized in our implementations. Uniprocessor and SMP parallel performance results of our recursive blocked algorithms and corresponding routines in the state-of-the-art libraries LAPACK and SLICOT are presented. The performance improvements of our recursive algorithms are remarkable, including 10-fold speedups compared to standard algorithms.
  • Drakare, Stina, et al. (författare)
  • Primary production and phytoplankton composition in relation to DOC input and bacterioplankton production in humic Lake Örträsket
  • 2002
  • Ingår i: Freshwater Biology. - 0046-5070. ; 47:1, s. 41-52
  • Tidskriftsartikel (refereegranskat)abstract
    • 1. The biomass and production of picophytoplankton, large phytoplankton and heterotrophic bacterioplankton were measured in humic Lake Örträsket, northern Sweden during four consecutive summers. 2. High flow episodes, carrying fresh dissolved organic carbon (DOC) into the lake, always stimulated heterotrophic bacterial production at the expense of primary production. Primary production never exceeded bacterial production for approximately 20 days after such an episode had replenished epilimnial DOC. We suggest that allochthonous DOC is an energy source that stimulates bacterioplankton that, because of their efficient uptake of inorganic nutrients, are then able to outcompete phytoplankton. After the exhaustion of readily available DOC, phytoplankton were able to dominate epilimnion production in Lake Örträsket. 3. Biomass production was higher when dominated by phytoplankton than by bacterioplankton, despite a similar utilization of nutrients in the epilimnion throughout the summer. We propose that different C : N : P ratios of bacterioplankton and phytoplankton permit the latter to produce more carbon (C) biomass per unit of available inorganic nutrients than bacterioplankton.
  • Hernroth, Bodil E., et al. (författare)
  • Environmental factors influencing human viral pathogens and their potential indicator organisms in the blue mussel, Mytilus edulis: the first Scandinavian report
  • 2002
  • Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 68:9, s. 4523-4533
  • Tidskriftsartikel (refereegranskat)abstract
    • This study was carried out in order to investigate human enteric virus contaminants in mussels from three sites on the west coast of Sweden, representing a gradient of anthropogenic influence. Mussels were sampled monthly during the period from February 2000 to July 2001 and analyzed for adeno-, entero-, Norwalk-like, and hepatitis A viruses as well as the potential viral indicator organisms somatic coliphages, F-specific RNA bacteriophages, bacteriophages infecting Bacteroides fragilis, and Escherichia coli. The influence of environmental factors such as water temperature, salinity, and land runoff on the occurrence of these microbes was also included in this study. Enteric viruses were found in 50 to 60% of the mussel samples, and there were no pronounced differences between the samples from the three sites. E. coli counts exceeded the limit for category A for shellfish sanitary safety in 40% of the samples from the sites situated in fjords. However, at the site in the outer archipelago, this limit was exceeded only once, in March 2001, when extremely high levels of atypical indole-negative strains of E. coli were registered at all three sites. The environmental factors influenced the occurrence of viruses and phages differently, and therefore, it was hard to find a coexistence between them. This study shows that, for risk assessment, separate modeling should be done for every specific area, with special emphasis on environmental factors such as temperature and land runoff. The present standard for human fecal contamination, E. coli, seems to be an acceptable indicator of only local sanitary contamination; it is not a reliable indicator of viral contaminants in mussels. To protect consumers and get verification of "clean" mussels, it seems necessary to analyze for viruses as well. The use of a molecular index of the human contamination of Swedish shellfish underscores the need for reference laboratories with high-technology facilities.
  • Jansson, Per-Anders, 1961-, et al. (författare)
  • Endocrine abnormalities in healthy first-degree relatives of type 2 diabetes patients--potential role of steroid hormones and leptin in the development of insulin resistance.
  • 2002
  • Ingår i: European journal of clinical investigation. - 0014-2972. ; 32:3, s. 172-8
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: First-degree relatives of type 2 diabetes patients are at risk of developing diabetes and they display several metabolic and hormonal perturbations. The interplay between insulin resistance, steroid hormones and circulating leptin is, however, still not fully explored in this group.DESIGN: Thirty-three healthy first-degree relatives of type 2 diabetic patients (relatives; M/F 19/14) were compared to 33 healthy subjects without a family history of diabetes (controls) and the groups were matched for gender, age and body mass index (BMI). We performed euglycaemic hyperinsulinaemic clamps and blood was sampled for hormone analyses.RESULTS: Relatives exhibited decreased insulin sensitivity (index of metabolic clearance rate of glucose; MCRI) but when genders were analysed separately, this difference was significant only in males (11.3 +/- 1.3 vs. 15.0 +/- 1.5 units, means +/- SEM, P = 0.030). In male relatives morning cortisol and testosterone levels were lower, whereas leptin was higher than in male controls (P = 0.018, 0.008 and 0.063, respectively). In male relatives plasma testosterone levels were significantly associated with insulin sensitivity (r = 0.48, P = 0.040). Circulating leptin levels were inversely correlated with insulin sensitivity in all subject groups (r-values -0.49 to -0.66; P &lt; 0.05, except in female control subjects P = 0.063). These associations were present also when age and BMI or waist:hip ratio were included in stepwise multiple regression analyses.CONCLUSION: Male subjects genetically predisposed for type 2 diabetes display several endocrine abnormalities including leptin, cortisol and testosterone levels. Dysregulation of these hormones may be important in the development of insulin resistance and type 2 diabetes.
  • Palmqvist, Kristina, et al. (författare)
  • CO2 exchange and thallus nitrogen across 75 contrasting lichen associations from different climate zones.
  • 2002
  • Ingår i: Oecologia. - 0029-8549. ; 133, s. 295-306
  • Tidskriftsartikel (refereegranskat)abstract
    • Aiming to investigate whether a carbon-to-nitrogen equilibrium model describes resource allocation in lichens, net photosynthesis (NP), respiration (R), concentrations of nitrogen (N), chlorophyll (Chl), chitin and ergosterol were investigated in 75 different lichen associations collected in Antarctica, Arctic Canada, boreal Sweden, and temperate/subtropical forests of Tenerife, South Africa and Japan. The lichens had various morphologies and represented seven photobiont and 41 mycobiont genera. Chl a, chitin and ergosterol were used as indirect markers of photobiont activity, fungal biomass and fungal respiration, respectively. The lichens were divided into three groups according to photobiont: (1) species with green algae, (2) species with cyanobacteria, and (3) tripartite species with green algal photobionts and cyanobacteria in cephalodia. Across species, thallus N concentration ranged from 1 to 50 mg g(-1) dry wt., NP varied 50-fold, and R 10-fold. In average, green algal lichens had the lowest, cyanobacterial Nostoc lichens the highest and tripartite lichens intermediate N concentrations. All three markers increased with thallus N concentration, and lichens with the highest Chl a and N concentrations had the highest rates of both P and R. Chl a alone accounted for ca. 30% of variation in NP and R across species. On average, the photosynthetic efficiency quotient [K-F=(NPmax+R)/R)] ranged from 2.4 to 8.6, being higher in fruticose green algal lichens than in foliose Nostoc lichens. The former group invested more N in Chl a and this trait increased NPmax while decreasing R. In general terms, the investigated lichens invested N resources such that their maximal C input capacity matched their respiratory C demand around a similar (positive) equilibrium across species. However, it is not clear how this apparent optimisation of resource use is regulated in these symbiotic organisms.
  • Schubert, Maria, et al. (författare)
  • Proteome map of the chloroplast lumen of Arabidopsis thaliana
  • 2002
  • Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 277:10, s. 8354-8365
  • Tidskriftsartikel (refereegranskat)abstract
    • The thylakoid membrane of the chloroplast is the center of oxygenic photosynthesis. To better understand the function of the luminal compartment within the thylakoid network, we have carried out a systematic characterization of the luminal thylakoid proteins from the model organism Arabidopsis thaliana. Our data show that the thylakoid lumen has its own specific proteome, of which 36 proteins were identified. Besides a large group of peptidyl-prolyl cis-trans isomerases and pro. teases, a family of novel PsbP domain proteins was found. An analysis of the luminal signal peptides showed that 19 of 36 luminal precursors were marked by a twin-arginine motif for import via the Tat pathway. To compare the model organism Arabidopsis with another typical higher plant, we investigated the proteome from the thylakoid lumen of spinach and found that the luminal proteins from both plants corresponded well. As a complement to our experimental investigation, we made a theoretical prediction of the luminal proteins from the whole Arabidopsis genome and estimated that the thylakoid lumen of the chloroplast contains similar to80 proteins.
  • Sun, J. G., et al. (författare)
  • Perturbation analysis of the periodic discrete-time algebraic Riccati equation
  • 2002
  • Ingår i: Siam Journal on Matrix Analysis and Applications. - 0895-4798 ; 24:2, s. 411-438
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper is devoted to the perturbation analysis for the periodic discrete-time algebraic Riccati equations (P-DAREs). Perturbation bounds and condition numbers of the Hermitian positive semidefinite solution set to the P-DAREs are obtained. The results are illustrated by numerical examples.
  • Svensson, M B, et al. (författare)
  • Adaptive stress response of glutathione and uric acid metabolism in man following controlled exercise and diet.
  • 2002
  • Ingår i: Acta Physiol Scand. - 0001-6772. ; 176:1, s. 43-56
  • Tidskriftsartikel (refereegranskat)abstract
    • Ergometer cycling performance as well as acute exercise-induced changes in the metabolism of energy-intermediates and glutathione (GSH) were investigated in skeletal muscle (SM) of 15 healthy young male subjects (VO(2max) approximately 54.7 mL kg(-1) min(-1), age approximately 25 years), before and after 3 days of controlled 'ìoverload-training' in combination with either high (62% of energy intake) or low (26% of energy intake) dietary intake of carbohydrates. The intake of a carbohydrate-rich diet clearly reduced the depletion of SM glycogen following the short-term training period, paralleled with a positive effect on the endurance performance, but not on high-intensity work-performance. An 'delayed over-reaching effect', defined as impaired work-performance, was observed after 2.5 days of recovery from the short-term training period, irrespective of the carbohydrate content of the diet and basal glycogen level in SM. Taken together, the main and novel findings of present investigation are: (1) an acute decrease of reduced GSH content and altered thiol-redox homeostasis in SM induced by strenuous high-intensity exercise; (2) an adaptive elevation of basal GSH level following the short-term training period; (3) an adaptive decrease of basal GSH level following 2.5 days recovery from training; (4) evidence of a relationship between the SM fibre type, physical performance capacity and GSH turnover during acute bouts of exercise; and (5) no evident effect of the level of carbohydrate intake on metabolism of GSH or energy intermediates. Furthermore, the induction of acute oxidative stress in exercising human SM and the adaptive responses to training are suggested to provide a protective antioxidant phenotype to the exercising SM during periods with repeated intense intermittent training.
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