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Sökning: WFRF:(Larson Earl T)

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1.
  • Sbarra, AN, et al. (författare)
  • Mapping routine measles vaccination in low- and middle-income countries
  • 2021
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 589:7842, s. 415-
  • Tidskriftsartikel (refereegranskat)abstract
    • The safe, highly effective measles vaccine has been recommended globally since 1974, yet in 2017 there were more than 17 million cases of measles and 83,400 deaths in children under 5 years old, and more than 99% of both occurred in low- and middle-income countries (LMICs)1–4. Globally comparable, annual, local estimates of routine first-dose measles-containing vaccine (MCV1) coverage are critical for understanding geographically precise immunity patterns, progress towards the targets of the Global Vaccine Action Plan (GVAP), and high-risk areas amid disruptions to vaccination programmes caused by coronavirus disease 2019 (COVID-19)5–8. Here we generated annual estimates of routine childhood MCV1 coverage at 5 × 5-km2pixel and second administrative levels from 2000 to 2019 in 101 LMICs, quantified geographical inequality and assessed vaccination status by geographical remoteness. After widespread MCV1 gains from 2000 to 2010, coverage regressed in more than half of the districts between 2010 and 2019, leaving many LMICs far from the GVAP goal of 80% coverage in all districts by 2019. MCV1 coverage was lower in rural than in urban locations, although a larger proportion of unvaccinated children overall lived in urban locations; strategies to provide essential vaccination services should address both geographical contexts. These results provide a tool for decision-makers to strengthen routine MCV1 immunization programmes and provide equitable disease protection for all children.
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2.
  • Haitina, Tatjana, et al. (författare)
  • Cloning, tissue distribution, pharmacology and three-dimensional modelling of melanocortin receptors 4 and 5 in rainbow trout suggest close evolutionary relationship of these subtypes
  • 2004
  • Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 380:2, s. 475-486
  • Tidskriftsartikel (refereegranskat)abstract
    • The rainbow trout (Oncorhynchus mykiss) is one of the most widely used fish species in aquaculture and physiological research. In the present paper, we report the first cloning, 3D (three-dimensional) modelling, pharmacological characterization and tissue distribution of two melanocortin (MC) receptors in rainbow trout. Phylogenetic analysis indicates that these receptors are orthologues of the human MC4 and MC5 receptors. We created 3D molecular models of these rainbow trout receptors and their human counterparts. These models suggest greater divergence between the two human receptors than between their rainbow trout counterparts. The pharmacological analyses demonstrated that ACTH (adrenocorticotropic hormone) had surprisingly high affinity for the rainbow trout MC4 and MC5 receptors, whereas alpha-, beta- and gamma-MSH (melanocyte-stimulating hormone) had lower affinity. In second-messenger studies, the cyclic MSH analogues MTII and SHU9119 acted as potent agonist and antagonist respectively at the rainbow trout MC4 receptor, indicating that these ligands are suitable for physiological studies in rainbow trout. Interestingly, we found that the rainbow trout MC4 receptor has a natural high-affinity binding site for zinc ions (0.5 microM) indicating that zinc may play an evolutionary conserved role at this receptor. Reverse transcription PCR indicates that the rainbow trout receptors are expressed both in peripheral tissues and in the central nervous system, including the telencephalon, optic tectum and hypothalamus. Overall, this analysis indicates that the rainbow trout MC4 and MC5 receptors have more in common than their mammalian counterparts, which may suggest that these two receptors have a closer evolutionary relationship than the other MC receptor subtypes.
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  • Haitina, Tatjana, et al. (författare)
  • Functional characterization of two melanocortin (MC) receptors in lamprey showing orthology to the MC1 and MC4 receptor subtypes
  • 2007
  • Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 7, s. 101-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background The melanocortin (MC) receptors have a key role in regulating body weight and pigmentation. They belong to the rhodopsin family of G protein-coupled receptors (GPCRs). The purpose of this study was to identify ancestral MC receptors in agnathan, river lamprey. Results We report cloning of two MC receptors from river lamprey. The lamprey receptors, designated MCa and MCb, showed orthology to the MC1 and MC4 receptor subtypes, respectively. The molecular clock analysis suggested that lamprey MC receptor genes were not duplicated recently and diverged from each other more than 400 MYR ago. Expression and pharmacological characterization showed that the lamprey MCa receptor was able to bind and be activated by both lamprey and human MSH peptides. The lamprey MCa receptor had relatively high affinity for ACTH derived peptides similarly to the fish MC receptors. We found that both of the lamprey MC receptors were expressed in skin, while the MCb receptor was also found in liver, heart and skeletal muscle. Conclusion This study shows presence of MC receptors in agnathans indicating early signs of specific functions of melanocortin receptor subtypes.
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  • Larsson, Tomas A, et al. (författare)
  • Characterization of NPY receptor subtypes Y2 and Y7 in rainbow trout Oncorhynchus mykiss
  • 2006
  • Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 27:6, s. 1320-1327
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the cloning and pharmacological characterization of two neuropeptide Y (NPY) receptor subtypes, Y2 and Y7, in rainbow trout (Oncorhynchus mykiss). These subtypes are approximately 50% identical to each other and belong to the Y2 subfamily of NPY receptors. The binding properties of the receptors were investigated after expression in human HEK-293 EBNA cells. Both receptors bound the three zebrafish peptides NPY, PYYa, and PYYb, as well as porcine NPY and PYY, with affinities in the nanomolar range that are similar to mammalian Y2. The affinity of the truncated porcine NPY fragments, NPY 13-36 and NPY 18-36 was markedly lower compared to mammalian and chicken Y2. This suggests that mammalian and chicken Y2 are unique among NPY receptors in their ability to bind truncated peptide fragments. The antagonist BIIE0246, developed for mammalian Y2, did not bind either of the two rainbow trout receptors. Our results support the proposed expansion of this gene family by duplications before the gnathostome radiation. They also reveal appreciable differences in the repertoire and characteristics of NPY receptors between fish and tetrapods stressing the importance of lineage-specific gene loss as well as sequence divergence after duplication.
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  • Larsson, Tomas, et al. (författare)
  • Cloning and sequence analysis of the neuropeptide Y receptors Y5 and Y6 in the coelacanth Latimeria chalumnae
  • 2007
  • Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 150:2, s. 337-342
  • Tidskriftsartikel (refereegranskat)abstract
    • Two coelacanth species, Latimeria chalumnae and Latimeria menadoensis, the recently discovered second species, have a key evolutionary position at the divergence of bony fishes and tetrapods. Together with lungfishes, they are the only living species separating the species-rich tetrapods from the other major group of vertebrates, the ray-finned fishes. The coelacanth is therefore of great importance for comparisons of gene families that differ between these two groups, such as the neuropeptide Y (NPY) receptor family. In this work we have sequenced the full-length genes for two NPY receptors in Latimeria chalumnae. Phylogenetic analysis indicated that the two sequences are orthologs of the mammalian Y5 and Y6 receptors. The Y5 gene has been implicated in appetite stimulation in mammals but is absent from teleost fishes. The presence of the Y5 receptor in Latimeria together with phylogenetic analysis shows that Y5 existed before the separation of bony fishes and tetrapods. The Latimeria receptor has about 62 % identity to tetrapod Y5 sequences and contains the extended third intracellular loop with several highly conserved motifs that may be involved in signal transduction. The Latimeria Y6 receptor has about 60% identity to tetrapod Y6 sequences. The functional role of Y6 is unclear as the gene is seemingly functional in some mammals but is non-functional in others. The Y6 receptor is also missing in teleost fishes. Our results confirm an early vertebrate origin for all NPY receptor subtypes presently found in mammals followed by differential gene loss in the different classes of vertebrates.
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  • Lepage, Olivier, et al. (författare)
  • Serotonin, but not melatonin, plays a role in shaping dorninant-subordinate relationships and aggression in rainbow trout
  • 2005
  • Ingår i: HORMONES AND BEHAVIOR. ; 48:2, s. 233-242
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to clarify to what extent the effects of elevated dietary L-tryptophan (Trp) on aggressive behavior and stress responsiveness in rainbow trout are mediated by circulating melatonin and central serotonin (5-HT), respectively. Isolated rainbow trout were paired for I It a day for 7 days in order to create fish with experience of being dominant and subordinate. Following this week, the fish were tested for aggressive behavior using a resident-intruder test after which they were subjected to one of four treatments: (1) tryptophan, (2) the selective serotonin reuptake inhibitor (SSRI) citalopram, (3) melatonin, and (4) no treatment (controls). After 7 days of treatment, the fish were subjected to a second resident-intruder test. Trp-supplemented feed resulted in a suppression of aggressive behavior in fish with experience of being dominant. Moreover, fish fed Trp-supplemented feed, regardless of social experience, also displayed lower plasma cortisol levels than controls. These effects of elevated dietary Trp were closely mimicked by citalopram treatment, whereas exogenous melatonin had no effect on either aggressive behavior or plasma cortisol. Thus, the effect of elevated dietary Trp on aggressive behavior and stress responses does not appear to be mediated by melatonin even though elevated dietary intake of Trp resulted in an increase in plasma melatonin concentrations.
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  • Lepage, Olivier, et al. (författare)
  • Tryptophan affects both gastrointestinal melatonin production and interrenal activity in stressed and nonstressed rainbow trout
  • 2005
  • Ingår i: Tryptophan affects both gastrointestinal melatonin production and interrenal activity in stressed and nonstressed rainbow trout. ; 38:4, s. 264-271
  • Tidskriftsartikel (refereegranskat)abstract
    • The present experiments were designed to test the hypothesis that elevated dietary levels of l-tryptophan (Trp) result in elevated plasma levels of melatonin and that this increase in plasma melatonin concentration is caused by elevated melatonin production and secretion by the gastro-intestinal-tract (GIT). Feeding juvenile rainbow trout (Oncorhynchus mykiss) Trp-supplemented feed for 7 days resulted in elevated daytime plasma levels of melatonin and reduced poststress plasma cortisol concentrations. Nighttime plasma melatonin concentrations were, however, not affected by elevated dietary Trp. Moreover, stress caused a reduction in daytime plasma levels of melatonin in fish fed Trp-supplemented feed, an effect that was counteracted by treatment with an alpha-receptor antagonist. These results clearly suggest that elevated dietary intake of Trp results in an increase in the GIT production of melatonin in rainbow trout. A suggestion that was further supported by the results from an in vitro experiment demonstrating that addition of Trp to the incubation medium stimulates melatonin production and release by incubated rainbow trout GIT. The results from this study led us to suggest a possible mechanism for melatonin in mediating the effects of elevated dietary Trp on poststress plasma cortisol concentrations and aggressive behavior in rainbow trout.
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14.
  • Salaneck, Erik, et al. (författare)
  • Birth and death of neuropeptide Y receptor genes in relation to the teleost fish tetraploidization
  • 2008
  • Ingår i: Gene. - : Elsevier BV. - 0378-1119 .- 1879-0038. ; 409:1-2, s. 61-71
  • Tidskriftsartikel (refereegranskat)abstract
    • Extensive evidence exists for a genome duplication in the fish lineage leading to the species-rich clade of the telcosts, comprising > 99% of the known actinopterygian (ray-finned) fish species. Our previous studies of the neuropeptide Y receptor (NPYR) gene family suggested an ancestral gnathostome repertoire of 7 genes in 3 subfamilies. However, studies in the zebrafish have earlier identified only 5 NPYR genes, despite the expected increase in gene number due to the teleost tetraploidization. Notably, receptors Y-1, Y-5 and Y-6 were missing in the zebrafish genome database and only Y-8 had been duplicated. We report here an investigation of the evolutionary history of the Y-1 subfamily (Y-1, Y-4, Y-6 and Y-8) and the Y-5 receptor. Seven basal actinopterygian species and a shark were investigated and a total of 22 gene fragments were cloned and analyzed. Our results show that subtypes Y-1, Y-5 and Y-6 still exist in species representing basal actinopterygian lineages (bichir, sturgeon, gar and bowfin) as well as in some basal teleost lineages. Surprisingly we identified a zebrafish Y-1 receptor, the first Y-1 receptor found in euteleosts. Thus, these findings confirm the ancestral gnathostome repertoire of 7 NPYR genes and show that many of these receptors are present in basal actinopterygians as well as some basal teleosts. NPYR losses seem to have occurred relatively recently in euteleosts because Y-1, Y-5 and Y-6 are absent in the genome databases of two pufferfishes as well as medaka and stickleback and Y-5 and Y-6 are absent in the zebrafish database. A duplicate of Y-8 seems to be the only remaining receptor gene resulting from the teleost tetraploidization. The unexpected absence of the two appetite-stimulating receptors Y-1 and Y-5 in some euteleosts, along with our discovery of duplicates of the peptide ligands NPY and PYY, has implications for the role of the NPY system in euteleost feeding behavior.
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15.
  • Schjolden, Joachim, et al. (författare)
  • Melanocortin peptides affect the motivation to feed in rainbow trout (Oncorhynchus mykiss)
  • 2009
  • Ingår i: General and Comparative Endocrinology. - : Elsevier. - 0016-6480 .- 1095-6840. ; 160:2, s. 134-138
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we investigated the effects of one melanocortin receptor (MCR) agonist and two antagonists on food intake in juvenile rainbow trout. Baseline food intake was established prior to 1 microl intracerebroventricular injection (ICV) of the non-specific agonist MTII, the MC4R antagonist HS024 and the MC3/4R antagonist SHU9119 at concentrations of 0.3, 1 or 3 nM. Saline-injected fish and untreated fish served as controls. Changes in food intake were observed 1h after the ICV injections. Our results showed that treatment with MTII significantly decreased food intake at 3 nM compared to control, HS024 significantly increased food intake at 3 nM compared to control and saline-treated fish, and SHU9119 significantly increased food intake at 3 nM compared to saline-treated fish. In conclusion, our study provides further evidence, and hence strengthens the hypothesis, that MC4R participates in the control of energy balance in fish in the same manner as in mammals. Our findings that HS024 is more potent than SHU9119 in increasing food intake suggest that the effects of melanocortin on energy balance in rainbow trout are mainly regulated by activation of MC4R. Hence, HS024 seems an excellent tool as a MC4R antagonist in rainbow trout.
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  • Resultat 1-16 av 16

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