Antrakinonin merkitys puuhakkeen neutraalisulfiittikeitossa

The aim of this thesis was to investigate the carcinogenic potential of anthraquinone (AQ) and verify the new proposed working mechanism of AQ in neutral sulphite pulping by using six different quinones with varying redox potentials. The idea behind the new working mechanism was to investigate whether additives with lower redox potential could be better antioxidants and thus more effective pulping chemicals. In addition, the much discussed AQ reaction mechanisms as well as the synergism of polysulfide (PS) and AQ will be covered. The cooking trials were performed in two stages. First it was examined how well the different quinones are reduced by the influence of sodium sulphite, and in the second stage it was investigated how efficient the different quinones were in neutral pulping of wood chips. The dissolved lignin content (DLC), molecular weight distribution (MWD) of lignin and final pH were determined from the filtrates. In addition, kappa number and total yield were measured from the cooked pulps. According to the results, there is clear evidence that AQ has the highest delignification rate of the trials. Although it seems that lower redox potential equals better delignification, it is not undoubtedly like that. In comparison to reference cooks, AQ was the only quinone which showed notable effect on the delignification rate. This might mean that the other additives used in the experiments could not work as pulping catalysts in given conditions and thus are unable to degrade lignin effectively. Alternative explanation could be that the reduced forms of quinones are just unable to degrade lignin as efficiently as anthrahydroquinone (AHQ), or simply they are not as stable as AHQ. Regarding the latest research, the utilization of AQ in pulping can be seen very questionable. However, it is still uncertain why it induces tumors in test animals, and what are harmful amounts to humans. Altogether based on the results of this study the understanding towards AQ is slightly increased, yet remaining unclear. In other words, it seems that the investigation of the working mechanism of AQ requires further exploration.Tämän diplomityön tavoitteena on kirjallisuutta apuna käyttäen selvittää syitä antrakinonin (AQ) mahdolliselle karsinogeenisuudelle, sekä kokeellisesti todentaa AQ:n uusi mahdollinen toimintamekanismi neutraalisulfiittikeitossa. Todentamisessa käytetään apuna kuutta erilaisen redox-potentiaalin omaavaa kinonia, joita altistetaan pelkistäville keitto-olosuhteille. Ajatus uuden toimintamekanismin taustalla on selvittää ovatko matalamman redox-potentiaalin omaavat lisäaineet parempia antioksidantteja ja siten tehokkaampia keittokemikaaleja. Lisäksi työssä käydään lyhyesti läpi kirjallisuudessa esiintyviä antrakinonin reaktiomekanismeja, sekä tarkastellaan AQ:n ja polysulfidin (PS) välistä synergiaa. Keittokokeet suoritettiin kahdessa osassa. Ensin selvitettiin kokeissa käytettävien kinoneiden kykyä pelkistyä natriumsulfiitin vaikutuksesta ja toisessa osassa tutkittiin kyseisten kinoneiden vaikutusta puuhakkeeseen neutraaleissa keitto-olosuhteissa. Liuenneen ligniinin pitoisuus, ligniinin molekyylimassajakauma, sekä loppu-pH mitattiin suodoksista. Lisäksi kappaluku ja kokonaissaanto mitattiin saaduista massoista. Tulosten mukaan on selkeää näyttöä siitä, että AQ poistaa ligniiniä kaikkein tehokkaimmin. Vaikka matalampi redox-potentiaali näyttäisi viittaavan parempaan delignifiointiasteeseen, asia ei ole yksiselitteinen. Verrattaessa lisäaineettomiin referenssikeittoihin, AQ oli kinoneista ainoa joka vaikutti merkittävästi puuhakkeen delignifiointiasteeseen. Tämä saattaa viitata siihen, etteivät muut lisäaineet välttämättä toimi katalyytinomaisesti annetuissa olosuhteissa, eivätkä siten pysty tehokkaaseen ligniinin poistoon. Vaihtoehtoisesti pelkistyneet kinonimuodot saattavat olla kykenemättömiä pilkkomaan ligniiniä yhtä tehokkaasti kuin antrahydrokinoni (AHQ), tai sitten niiden pelkistyneet muodot eivät yksinkertaisesti ole yhtä stabiileja kuin AHQ. Viimeisimpien tutkimusten mukaan antrakinonin käyttö sellun keitossa voidaan nähdä hyvin kyseenalaisena. Kuitenkin on yhä epävarmaa miksi AQ aiheuttaa syöpää testieläimissä ja millaisia ovat ihmisille haitalliset annosmäärät. Joka tapauksessa, tämän tutkimuksen perusteella voidaan todeta että ymmärrys antrakinonia kohtaan on hieman lisääntynyt, vaikkakaan ei ratkaisevasti. Näyttää siis siltä, että AQ:n toimintamekanismin selvittäminen vaatii lisätutkimuksia

Sarcina ventriculi in blood: the first documented report since 1872

Peer reviewe

QTR-FRET: Efficient background reduction technology in time-resolved förster resonance energy transfer assays

A novel homogeneous assay system QTR-FRET (Quencher modulated Time-Resolved Forster Resonance Energy Transfer) combining quenching resonance energy transfer (QRET) and time-resolved Forster resonance energy transfer (TR-FRET) was developed to reduce background signal in the conventional energy transfer applications. The TR-FRET functionality is often limited by the lanthanide donor background signal leading to the use of low donor concentration. QTR-FRET reduces this background by introducing soluble quencher molecule, and in this work the concept functionality was proven and compared to previously introduced QRET and TR-FRET technologies. Comparison was performed with three different Eu3+-chelates exhibiting different luminescent lifetime and stability. The side-by-side comparison of the three signaling systems and Eu3+ -chelates was demonstrated in a model assay with Eu3+-chelate conjugated biotin and streptavidin (SA) or Cy5-SA conjugate. Comparison of the methodologies showed increased signal-to-background ratios when comparing QTR-FRET to TR-FRET, especially at high Eu3+ -biotin concentrations. Quenching the non-bound Eu3+-biotin improved the assay performance, which suggests that an improved assay performance can be attained with the QTR-FRET method. QTR-FRET is expected to be especially useful for Eu3+-labeled ligands with low affinity or assays requiring high Eu3+-ligand concentration. The QTR-FRET indicated potential for multi-analyte approaches separately utilizing the direct QRET-type Eu3+-chelate signal and energy transfer signal readout in a single- well. This potential was hypothesized with Avi-KRAS nucleotide exchange assay as a second biologically relevant model system

Chlamydia trachomatis samples testing falsely negative in the Aptima Combo 2 test in Finland, 2019

Since February 2019, over 160 Chlamydia trachomatis (CT) cases testing negative or equivocal by Aptima Combo 2 (AC2) but positive by Aptima CT test run with Panther instruments occurred in Finland. The AC2 test targets chlamydial 23S rRNA while the CT test targets 16S rRNA. Sequencing of 10 strains revealed a nucleotide substitution in 23S rRNA. The significance of this for the failure of the AC2 test to detect the variant is not yet known.Peer reviewe

Long-Lasting T Cell Responses in BNT162b2 COVID-19 mRNA Vaccinees and COVID-19 Convalescent Patients

Peer reviewe

Chlamydia trachomatis samples testing falsely negative in the Aptima Combo 2 test in Finland, 2019

Since February 2019, over 160 Chlamydia trachomatis (CT) cases testing negative or equivocal by Aptima Combo 2 (AC2) but positive by Aptima CT test run with Panther instruments occurred in Finland. The AC2 test targets chlamydial 23S rRNA while the CT test targets 16S rRNA. Sequencing of 10 strains revealed a nucleotide substitution in 23S rRNA. The significance of this for the failure of the AC2 test to detect the variant is not yet known

Long-Lasting T Cell Responses in BNT162b2 COVID-19 mRNA Vaccinees and COVID-19 Convalescent Patients

The emergence of novel variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made it more difficult to prevent the virus from spreading despite available vaccines. Reports of breakthrough infections and decreased capacity of antibodies to neutralize variants raise the question whether current vaccines can still protect against COVID-19 disease. We studied the dynamics and persistence of T cell responses using activation induced marker (AIM) assay and Th1 type cytokine production in peripheral blood mononuclear cells obtained from BNT162b2 COVID-19 mRNA vaccinated health care workers and COVID-19 patients. We demonstrate that equally high T cell responses following vaccination and infection persist at least for 6 months against Alpha, Beta, Gamma, and Delta variants despite the decline in antibody levels.</p