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- Ericson, Y, et al.
(författare)
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Faktablad från Integrerad kustfiskövervakning: Torhamn (södra Egentliga Östersjön) 2002-2015
- 2016
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Ingår i: Faktablad 2016 från Inst för Akvatiska resurser, SLU. ; :2016:4
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Faktabladet presenterar resultat och bedömningar från den integrerade kustfiskövervakningen i Torhamnsområdet under tidsperioden 2002-2015. Resultaten från tretton års undersökningar visar en alltmer tydlig påverkan på hälsotillståndet hos abborre liknande den som observeras hos abborre och tånglake i andra kustreferensområden. Denna tydliga och successiva påverkan som ses på abborrens hälsa på individnivå har ännu inte resulterat i några påtagliga förändringar på bestånds- eller samhällsnivå.
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- Hammarskjöld, Fredrik, et al.
(författare)
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Possible transmission of Candida albicans on an intensive care unit : intensive care unit
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Nosocomial transmission of Candida spp. has not fully been explored and previous studies have shown conflicting results.Aim: To evaluate the possible nosocomial transmission of Candida spp. on an intensive care unit (ICU).Methods: We conducted a prospective study over 19 month, including all patients on our ICU with growth of Candida spp. from surveillance and directed cultures. Molecular typing, with rep-PCR (DiversiLab) was used to define genotype relationships between the C. albicans and C. glabrata isolates. Candida isolates obtained from blood cultures taken from patients in our county outside the ICU, were used as a reference. Temporal cluster analysis was performed to evaluate genotype distribution over time.Findings: Seventy-seven patients with 78 ICU stays, representing twelve per cent of all ICU stays, were found to harbour 180 isolates of Candida spp. Molecular typing revealed 27 C. albicans genotypes and ten of C. glabrata. Possible clustering, indicated by overlapping stays of patients with indistinguishable candida genotypes was observed on seven occasions with C. albicans and on two occasions with C. glabrata. Two C. albicans genotypes were found significantly more often in the ICU group compared to the reference group. Moreover, C. albicans genotypes isolated from more than one patient were significantly more often found in the ICU group. Temporal cluster analysis revealed a significantly increased number of pairs with indistinguishable genotypes at a 21-dayinterval, indicating clustering.Conclusion: This study indicates transmission of C. albicans between ICU patients based on genotyping and temporal cluster analysis.
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- Helin, Anu S., et al.
(författare)
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From genes to function : variation in antimicrobial activity of avian β-defensin peptides from mallards
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Avian β-defensins are an important class of antimicrobial peptides in birds. These short cationic peptides are directly involved in the clearance of infections by membrane disruption, but can also act as immunomodulators and chemotactic agents recruiting immune cells. Recent genomic studies have shown the presence of several different avian β-defensin (AvBD) genes across the avian phylogeny, but also significant copy number variation and occurrence of pseudogenes. In mallard (Anas platyrhynchos) and other waterfowl AvBD genes are conserved and seem to be maintained by purifying selection. Due to their relatively simple peptide structure and direct mode of action, AvBDs is a potential tractable system to investigate how small differences in the gene sequence translates into differences in immune function. Here, we used genomic information from three different mallard defensin loci (AvBD4, AvBD10 and AvBD13) and synthesized the linear peptides from the most common allele of each locus, plus two rare alleles from AvBD13 locus and measured their antimicrobial activity against Gram-negative (E. coli and S. Typhimurium) and Gram-positive (S. aureus and M. luteus) bacteria. In these assays, AvBD4 showed the most potent antibacterial activity against both Gram-negative and Gram-positive bacteria, with an IC50 value of 0.48 mM against S. Typhimurium. Among AvBD13 peptides, the less frequently observed AvBD13:2 variant, was most potent, with IC50 value against S. aureus approximately 15 times lower than that of the most common AvBD13:1. Interestingly, AvBD10 had no antibacterial effect on the tested bacteria. Thus, antimicrobial function varied substantially among loci, but also within the AvBD13 locus, suggesting a direct link between genetic variation and immune function variation. Interestingly, results from assays with AvBD4 and AvBD13 seem to indicate that a higher positive net charge in peptides is associated with a more potent antibacterial effect.
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- Helin, Anu S., et al.
(författare)
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Relation between structure and function of three AvBD3b variants from mallard (Anas platyrhynchos)
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Defensins are multifunctional antimicrobial peptides expressed in several tissue types and leucocytes as part of the innate immune response against microbes. Based on the three-dimensional structure and disulfide connectivity, vertebrate defensins are subdivided into α-, β-, and θ-defensins. While all three types have been found in mammals, only β-defensins have been identified in birds. Genetic studies have revealed dozens of different avian β-defensin (AvBD) genes in different bird species, as well as allelic variation for different genes. Knowledge of the relation between avian peptide structure features and antimicrobial activity is however limited. In this study, the structure-functional relations of three variants of AvBD3b, a mallard (Anas platyrhynchos) defensin of evolutionary interest, was investigated. Gene alleles encoding two of these peptides, AvBD3b:1 and AvBD3b:2 are common in mallards, whereas AvBD3b:3 occurs rare. These β-defensin peptides were synthesized as linear peptides and subjected to oxidative folding. The three-dimensional structure of AvBD3b:1, including disulfide bond connectivity, was determined using NMR, and those of AvBD3b:2 and AvBD3b:3 respectively, were modelled using AvBD3b:1 as the template. The antimicrobial activities of folded peptides were compared to those of linear peptides. The NMR analysis showed that folded AvBD3b adopts a three-dimensional structure typical for β-defensins, including C-terminal antiparallel β-sheets and disulfide bond organization between six cysteine (C) residues: C6-C34, C13-C28, and C18-C35. Analyses of antimicrobial activity showed that both folded and linear variants of the three peptides inhibited bacterial growth. However, differences in activity were observed, suggesting that folded AvBD3b:3 was the most efficient against both Gram-negative and Gram-positive bacteria. Taken together, these findings provide additional insight into the influence of amino acid sequence variation and three-dimensional structure on the antimicrobial activity of mallard AvBD3b.
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- Höglund, Linda, et al.
(författare)
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Studies of photocurrent and dark current in quantum dots-in-a-well infrared photodetectors
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The performance of quantum dots-in-a-well infrared photodetectors (DWELL IPs) has been studied by means of interband and intersubband photocurrent measurements as well as dark current measurements. Using interband photocurrent measurements, substantial escape of electrons from lower lying states in the DWELL structure at large biases was revealed. Furthermore, a significant variation of the escape probability from energy states in the DVELL sturcture with voltage was observed. These facts could be possible explanations to the strong temperature and voltage dependence of hoth photocurrent and dark current in DWELL IPs. In a comparison between DWELL IPs and quantum well infrared photocdetectors (QWIPs), the dark current was shown to be considerably lower in DWELL IPs than in QWIPs, but alos the responsivity was low in comparison to QWIPs.
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