54 research outputs found

    Yhdysvaltain luottopolitiikka 1944–1947 ja Suomi

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    Tiivistelmä. Tutkielmassa tarkastellaan Yhdysvaltain luottopolitiikkaa Suomen suhteen vuosien 1944–1947 aikana. Tutkimuksella selvitetään, millaista Yhdysvaltain luottopolitiikka Suomen suhteen oli ja mitkä tekijät sitä määrittivät. Tämän lisäksi tutkielmassa tarkastellaan Yhdysvaltain ja Suomen välisten luottoneuvotteluiden etenemistä ja neuvotteluita hallinneita teemoja. Tutkimusaineistona toimii asiakirja-arkisto ”Foreign Relations of United States”. Asiakirjoja tarkastellaan sisällönanalyysia hyödyntäen. Valtaosa aineistosta muodostuu Yhdysvaltain diplomaattien ja poliitikkojen kirjoittamista sähkeistä. Yhdysvaltain luottopolitiikassa Suomen suhteen on havaittavissa eri vaiheita. Vuodesta 1944 aina vuoden 1945 syksyyn asti Yhdysvaltain politiikka hallitsi näkemys olla tukematta maita, joilla oli sotakorvausvelvoitteita. Tämän takia maa vastusti tuolloin Suomen luotottamista. Pitkälti maan haluttomuus olla tukematta sotakorvausvelvollisia valtioita johtui Yhdysvaltain huonoista kokemuksista ensimmäisen maailmansodan jälkeen, jolloin se oli epäsuorasti joutunut maksamaan Saksan sotakorvauksia. Tämän lisäksi Yhdysvaltain huomio oli vuosien 1944–1945 aikana kiinnittynyt toiseen maailmansotaan, eikä sillä sen takia ollut kiinnostusta Suomen luotottamiseen. Vuoden 1945 lopussa Yhdysvaltain kielteinen linja muuttui ja maa oli sittenkin valmis luotottamaan Suomea. Syitä linjan muuttumiselle oli useita. Erityisesti globaalin tilanteen muuttuminen vaikutti Yhdysvaltain päätökseen luotottaa Suomea. Kehitys oli johtamassa lännen ja idän väliseen kaksintaisteluun. Neuvostoliiton vaikutusvalta oli kasvanut sodan seurauksena ja Suomen itsenäisyyden menetys nähtiin yhtenä uhkakuvana Yhdysvalloissa. Yhdysvallat halusikin taloudellisen tuen avulla vankistaa Suomen itsenäistä asemaa. Näin Suomen taloudellinen tukeminen kytkeytyi osaksi maan kylmän sodan aikaista taloudellista sodankäyntiä. Suomi nähtiin yhtenä kylmän sodan kohteista ja maan taloudellisella tukemisella pyrittiin patoamaan kommunismin leviämistä vankistamalla Suomen sisäisiä oloja. Tämän lisäksi Yhdysvallat halusi myös säilyttää asemansa Suomen markkinoilla ja tukea samalla Suomen vientiä. Yhdysvaltain tuotantokapasiteetti oli kasvanut merkittävästi toisen maailmansodan aikana ja se tarvitsikin tuotteilleen markkina-alueita. Luottokysymykset hallitsivat maiden välistä vuoropuhelua koko tutkittavan ajanjakson ajan. Vuosien 1944–1945 aikana Yhdysvaltain diplomaattien ja suomalaispoliitikkojen välisissä keskusteluissa suomalaispoliitikot nostivat jatkuvasti esiin Suomen tarpeen luotolle. Yhdysvaltain edustajat taas korostivat yhä uudestaan ja uudestaan maan kielteistä suhtautumista luottoihin. Yhdysvaltain myönnyttyä Suomen luotottamiseen vuoden 1945 lopussa eivät luottokysymykset kuitenkaan jäänet taka-alalle maiden edustajien keskusteluissa, vaan vuosien 1946–1947 aikana maiden välisessä keskustelussa suomalaispoliitikot jatkoivat ahkerasti lisäluottojen metsästämistä, mikä tuottikin lopulta tulosta

    Genotypic and phenotypic diversity of Lactobacillus rhamnosus clinical isolates, their comparison with strain GG and their recognition by complement system

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    Lactobacillus rhamnosus strains are ubiquitous in fermented foods, and in the human body where they are commensals naturally present in the normal microbiota composition of gut, vagina and skin. However, in some cases, Lactobacillus spp. have been implicated in bacteremia. The aim of the study was to examine the genomic and immunological properties of 16 clinical blood isolates of L. rhamnosus and to compare them to the well- studied L. rhamnosus probiotic strain GG. Blood cultures from bacteremic patients were collected at the Helsinki University Hospital laboratory in 2005-2011 and L. rhamnosus strains were isolated and characterized by genomic sequencing. The capacity of the L. rhamnosus strains to activate serum complement was studied using immunological assays for complement factor C3a and the terminal pathway complement complex (TCC). Binding of complement regulators factor H and C4bp was also determined using radioligand assays. Furthermore, the isolated strains were evaluated for their ability to aggregate platelets and to form biofilms in vitro. Genomic comparison between the clinical L. rhamnosus strains showed them to be clearly different from L. rhamnosus GG and to cluster in two distinct lineages. All L. rhamnosus strains activated complement in serum and none of them bound complement regulators. Four out of 16 clinical blood isolates induced platelet aggregation and/or formed more biofilms than L. rhamnosus GG, which did not display platelet aggregation activity nor showed strong biofilm formation. These findings suggest that clinical L. rhamnosus isolates show considerable heterogeneity but are clearly different from L. rhamnosus GG at the genomic level. All L. rhamnosus strains are still normally recognized by the human complement system.Peer reviewe

    Characterization of Highly Mucus-Adherent Non-GMO Derivatives of Lacticaseibacillus rhamnosus GG

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    Lacticaseibacillus rhamnosusGG is one of the best studied lactic acid bacteria in the context of probiotic effects.L. rhamnosusGG has been shown to prevent diarrhea in children and adults and has been implicated to have mitigating or preventive effects in several disorders connected to microbiota dysbiosis. The probiotic effects are largely attributed to its adhesive heterotrimeric sortase-dependent pili, encoded by thespaCBA-srtC1gene cluster. Indeed, the strain-specific SpaCBA pili have been shown to contribute to adherence, biofilm formation and host signaling. In this work we set out to generate non-GMO derivatives ofL. rhamnosusGG that adhere stronger to mucus compared to the wild-type strain using chemical mutagenesis. We selected 13 derivatives that showed an increased mucus-adherent phenotype. Deep shotgun resequencing of the strains enabled division of the strains into three classes, two of which revealed SNPs (single nucleotide polymorphisms) in thespaAandspaCgenes encoding the shaft and tip adhesive pilins, respectively. Strikingly, the other class derivatives demonstrated less clear genotype - phenotype relationships, illustrating that pili biogenesis and structure is also affected by other processes. Further characterization of the different classes of derivatives was performed by PacBio SMRT sequencing and RNAseq analysis, which resulted in the identification of molecular candidates driving pilin biosynthesis and functionality. In conclusion, we report on the generation and characterization of three classes of strongly adherentL. rhamnosusGG derivatives that show an increase in adhesion to mucus. These are of special interest as they provide a window on processes and genes driving piliation and its control inL. rhamnosusGG and offer a variety of non-GMO derivatives of this key probiotic strain that are applicable in food products.Peer reviewe

    The N-Terminal GYPSY Motif Is Required for Pilin-Specific Sortase SrtC1 Functionality in Lactobacillus rhamnosus Strain GG

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    Predominantly identified in pathogenic Gram-positive bacteria, sortase-dependent pili are also found in commensal species, such as the probiotic-marketed strain Lactobacillus rhamnosus strain GG. Pili are typically associated with host colonization, immune signalling and biofilm formation. Comparative analysis of the N-terminal domains of pilin-specific sortases from various piliated Gram-positive bacteria identified a conserved motif, called GYPSY, within the signal sequence. We investigated the function and role of the GYPSY residues by directed mutagenesis in homologous (rod-shaped) and heterologous (coccoid-shaped) expression systems for pilus formation. Substitutions of some of the GYPSY residues, and more specifically the proline residue, were found to have a direct impact on the degree of piliation of Lb. rhamnosus GG. The present findings uncover a new signalling element involved in the functionality of pilin-specific sortases controlling the pilus biogenesis of Lb. rhamnosus GG and related piliated Gram-positive species.Peer reviewe

    Characterization of Highly Mucus-Adherent Non-GMO Derivatives of Lacticaseibacillus rhamnosus GG

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    Lacticaseibacillus rhamnosusGG is one of the best studied lactic acid bacteria in the context of probiotic effects.L. rhamnosusGG has been shown to prevent diarrhea in children and adults and has been implicated to have mitigating or preventive effects in several disorders connected to microbiota dysbiosis. The probiotic effects are largely attributed to its adhesive heterotrimeric sortase-dependent pili, encoded by thespaCBA-srtC1gene cluster. Indeed, the strain-specific SpaCBA pili have been shown to contribute to adherence, biofilm formation and host signaling. In this work we set out to generate non-GMO derivatives ofL. rhamnosusGG that adhere stronger to mucus compared to the wild-type strain using chemical mutagenesis. We selected 13 derivatives that showed an increased mucus-adherent phenotype. Deep shotgun resequencing of the strains enabled division of the strains into three classes, two of which revealed SNPs (single nucleotide polymorphisms) in thespaAandspaCgenes encoding the shaft and tip adhesive pilins, respectively. Strikingly, the other class derivatives demonstrated less clear genotype - phenotype relationships, illustrating that pili biogenesis and structure is also affected by other processes. Further characterization of the different classes of derivatives was performed by PacBio SMRT sequencing and RNAseq analysis, which resulted in the identification of molecular candidates driving pilin biosynthesis and functionality. In conclusion, we report on the generation and characterization of three classes of strongly adherentL. rhamnosusGG derivatives that show an increase in adhesion to mucus. These are of special interest as they provide a window on processes and genes driving piliation and its control inL. rhamnosusGG and offer a variety of non-GMO derivatives of this key probiotic strain that are applicable in food products

    Lactobacillus rhamnosus GG Outcompetes Enterococcus faecium via Mucus-Binding Pili : Evidence for a Novel and Heterospecific Probiotic Mechanism

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    Vancomycin-resistant enterococci (VRE) have become a major nosocomial threat. Enterococcus faecium is of special concern, as it can easily acquire new antibiotic resistances and is an excellent colonizer of the human intestinal tract. Several clinical studies have explored the potential use of beneficial bacteria to weed out opportunistic pathogens. Specifically, the widely studied Lactobacillus rhamnosus strain GG has been applied successfully in the context of VRE infections. Here, we provide new insight into the molecular mechanism underlying the effects of this model probiotic on VRE decolonization. Both clinical VRE isolates and L. rhamnosus GG express pili on their cell walls, which are the key modulators of their highly efficient colonization of the intestinal mucosa. We found that one of the VRE pilus clusters shares considerable sequence similarity with the SpaCBA-SrtC1 pilus cluster of L. rhamnosus GG. Remarkable immunological and functional similarities were discovered between the mucus-binding pili of L. rhamnosus GG and those of the clinical E. faecium strain E1165, which was characterized at the genome level. Moreover, E. faecium strain E1165 bound efficiently to mucus, which may be prevented by the presence of the mucus-binding SpaC protein or antibodies against L. rhamnosus GG or SpaC. These results present experimental support for a novel probiotic mechanism, in which the mucus-binding pili of L. rhamnosus GG prevent the binding of a potential pathogen to the host. Hence, we provide a molecular basis for the further exploitation of L. rhamnosus GG and its pilins for prophylaxis and treatment of VRE infections.Peer reviewe

    Probiotic Gut Microbiota Isolate Interacts with Dendritic Cells via Glycosylated Heterotrimeric Pili

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    Mapping of the microbial molecules underlying microbiota-host interactions is key to understand how microbiota preserve mucosal homeostasis. A pivotal family of such bacterial molecules are pili. Pili are proteinaceous cell wall appendages with a well-documented role in adhesion, whilst their role in immune interaction with the host is less established. Gram-positive pili are often posttranslationally modified by sortase-specific cleavage reactions and the formation of intramolecular peptide bonds. Here we report glycosylation as a new level of posttranslational modification of sortase-dependent pili of a beneficial microbiota species and its role in immune modulation. We focused on the SpaCBA pili of the model probiotic and beneficial human gut microbiota isolate Lactobacillus rhamnosus GG. A unique combination of molecular techniques, nanoscale mechanical and immunological approaches led to the identification of mannose and fucose residues on the SpaCBA pili. These glycans on the pili are recognized by human dendritic cells via the C-type lectin receptor DC-SIGN, a key carbohydrate-dependent immune tailoring pattern recognition receptor. This specific lectin-sugar interaction is moreover of functional importance and modulated the cytokine response of dendritic cells. This provides insight into the direct role bacterial glycoproteins can play in the immunomodulation of the host. Modification of the complex heterotrimeric pili of a model probiotic and microbiota isolate with mannose and fucose is of importance for the functional interaction with the host immune lectin receptor DC-SIGN on human dendritic cells. Our findings shed light on the yet underappreciated role of glycoconjugates in bacteria-host interactions.Peer reviewe
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