NADPH-Dependent Thioredoxin System In Regulation of Chloroplast Functions

Photosynthesis, the process in which carbon dioxide is converted into sugars using the energy of sunlight, is vital for heterotrophic life on Earth. In plants, photosynthesis takes place in specific organelles called chloroplasts. During chloroplast biogenesis, light is a prerequisite for the development of functional photosynthetic structures. In addition to photosynthesis, a number of other metabolic processes such as nitrogen assimilation, the biosynthesis of fatty acids, amino acids, vitamins, and hormones are localized to plant chloroplasts. The biosynthetic pathways in chloroplasts are tightly regulated, and especially the reduction/oxidation (redox) signals play important roles in controlling many developmental and metabolic processes in chloroplasts. Thioredoxins are universal regulatory proteins that mediate redox signals in chloroplasts. They are able to modify the structure and function of their target proteins by reduction of disulfide bonds. Oxidized thioredoxins are restored via the action of thioredoxin reductases. Two thioredoxin reductase systems exist in plant chloroplasts, the NADPHdependent thioredoxin reductase C (NTRC) and ferredoxin-thioredoxin reductase (FTR). The ferredoxin-thioredoxin system that is linked to photosynthetic light reactions is involved in light-activation of chloroplast proteins. NADPH can be produced via both the photosynthetic electron transfer reactions in light, and in darkness via the pentose phosphate pathway. These different pathways of NADPH production enable the regulation of diverse metabolic pathways in chloroplasts by the NADPH-dependent thioredoxin system. In this thesis, the role of NADPH-dependent thioredoxin system in the redox-control of chloroplast development and metabolism was studied by characterization of Arabidopsis thaliana T-DNA insertion lines of NTRC gene (ntrc) and by identification of chloroplast proteins regulated by NTRC. The ntrc plants showed the strongest visible phenotypes when grown under short 8-h photoperiod. This indicates that i) chloroplast NADPH-dependent thioredoxin system is non-redundant to ferredoxinthioredoxin system and that ii) NTRC particularly controls the chloroplast processes that are easily imbalanced in daily light/dark rhythms with short day and long night. I identified four processes and the redox-regulated proteins therein that are potentially regulated by NTRC; i) chloroplast development, ii) starch biosynthesis, iii) aromatic amino acid biosynthesis and iv) detoxification of H2O2. Such regulation can be achieved directly by modulating the redox state of intramolecular or intermolecular disulfide bridges of enzymes, or by protecting enzymes from oxidation in conjunction with 2-cysteine peroxiredoxins. This thesis work also demonstrated that the enzymatic antioxidant systems in chloroplasts, ascorbate peroxidases, superoxide dismutase and NTRC-dependent 2-cysteine peroxiredoxins are tightly linked up to prevent the detrimental accumulation of reactive oxygen species in plants.Siirretty Doriast

Crohnin taudin suolikirurgia

English summar

Surgical recurrence in Crohn's disease : a comparison between different types of bowel resections

To compare recurrence frequency and location between different types of bowel resections in Crohn's disease patients. This was a retrospective study of consecutive patients undergoing bowel resection for Crohn's disease between 2006 and 2016. Type of primary operation was recorded and grouped as ileocolic resection, small bowel resection, segmental colon resection with colocolic anastomosis or colorectal anastomosis, colectomy with ileorectal anastomosis, or end stoma operation. Binary logistic regression was used to compare surgical recurrence frequency between groups. We also investigated how Crohn's disease location at reoperations was related to the primary bowel resection type. Altogether, 218 patients with a median follow-up of 4.7 years were included in our study. Reoperation was performed in 42 (19.3%) patients. The risk of reoperation using the ileocolic resection group as reference was the following: small bowel resection (odds ratio (OR) 2.95, 95% confidence interval (CI) 1.01-8.66; P = 0.049), segmental colon resection with colocolic or colorectal anastomosis (OR 6.20, 95% CI 2.04-18.87; P = 0.001), colectomy with ileorectal anastomosis (OR 26.57, 95% CI 2.59-273.01; P = 0.006), and end stoma operation (OR 4.62, 95% CI 1.90-11.26; P = 0.001). In case of surgical recurrence, the reoperation type and location correlated with the primary bowel resection type. Reoperation frequency in Crohn's disease is lower after ileocolic resection than after other types of bowel resections. Surgical recurrence in Crohn's disease tends to maintain the disease location of the primary operation. One third of Crohn's patients undergoing an end stoma operation will still need new bowel resections due to recurrence.Peer reviewe

Public participation in monitoring programmes as a tool for lakeshore monitoring: the example of Lake Pyhäjärvi, Karelia, Eastern Finland

AbstractLake Pyhäjärvi, on the border between Finland and Russia in Karelia, is a very valuable clear-water lake of the Lobelia type. It belongs to the European Union's Natura 2000 programme in Finland, and has been included in regional and national monitoring programmes since the 1960s. The main monitoring station is situated near the outlet of the lake. Deterioration of its water quality was suspected already in the 1980s because of decreasing Secchi depths (transparency) and increasing chlorophyll a.The occurrence of algal blooms on the lakeshores is monitored weekly during each summer at one site on Lake Pyhäjärvi (site 1). This is a part of nationwide intensive algae monitoring programme organised by the environmental authorities together with voluntary observers at some 270 lake sites in Finland since 1998. Since 1997, Secchi depth observations have been carried out by volunteers biweekly or monthly at 17 sites on the lake. In the vicinity of one of these transparency observation sites (station 100), intensive monitoring of algae has been carried out. At this lakeshore monitoring site 69 algal observations were made, ten of which recorded algal blooms during the study period 1998–2002. The observed algal blooms were caused by algae of the Anabaena species, mainly by Anabaena lemmermannii. At Lake Pyhäjärvi the number of algal bloom observations received from the public have decreased from the 1990s to the 2000s. The range of Secchi disc transparency was 5.0–8.4 m with a mean value of 6.2 m at station 100 and 4.3–7.7 m (mean 6.1 m) at the main monitoring station 2 during the open water periods in 1998–2002. During this study period, the maximum values at site 100 seem to have increased slightly, which might indicate some improvement in the water quality due to decreased point source loading.We conclude that the intensive algal monitoring results of 5 years at the lakeshore site and the transparency results — both compiled by trained volunteers — reflect an improvement in the state of Lake Pyhäjärvi in Karelia. This conclusion is in accordance with the long-term water quality and short-core studies of sedimentary diatoms in Lake Pyhäjärvi. We suggest that the intensive algal observations and transparency measurements are both suitable methods for the monitoring of lakeshores and lakes, and that both are suitable for voluntary monitoring. We found public participation a good tool for monitoring lakes and lakeshores

The prognostic value of extramural venous invasion in preoperative MRI of rectal cancer patients

Aim This study aimed to examine the prognostic value of extramural venous invasion observed in preoperative MRI on survival and recurrences. Method In total, 778 rectal cancer patients were evaluated in multidisciplinary meetings in Helsinki University Hospital during the years 2016-2018. 635 patients met the inclusion criteria of stage I-III disease and were intended for curative treatment at the time of diagnosis. 128 had extramural venous invasion in preoperative MRI. Results The median follow-up time was 2.5 years. In a univariate analysis extramural venous invasion was associated with poorer disease-specific survival (hazard ratio [HR] 2.174, 95% CI 1.118-4.224, P = 0.022), whereas circumferential margin = T3c or nodal positivity were not. Disease recurrence occurred in 17.3% of the patients: 13.4% had metastatic recurrence only, 1.7% mere local recurrence and 2.2% both metastatic and local recurrence. In multivariate analysis, extramural venous invasion (HR 1.734, 95% CI 1.127-2.667, P = 0.012) and nodal positivity (HR 1.627, 95% CI 1.071-2.472, P = 0.023) were risk factors for poorer disease-free survival (DFS). Circumferential marginPeer reviewe

Kasviplanktonanalyysin laadunvarmistus

Biologisten määritysten laadunvarmennuksen merkitys on korostunut EU:n vesipuitedirektiivin (VPD) voimaantulon myötä, sillä vesistöjen ekologisen tilan luokittelu edellyttää, että käytössä on laadukasta ja vertailukelpoista tietoa biologisista laatutekijöistä. Suomen ympäristökeskus SYKE on toiminut vuodesta 2001 kansallisena ympäristöalan vertailulaboratoriona pätevyysalueena vesien ja kiinteiden ympäristönäytteiden ympäristökemiallinen ja ekotoksikologinen mittaus-, testaus- ja näytteenottotoiminta. SYKEssä alkoi vuonna 2005 hanke vertailulaboratorion pätevyysalueen laajentamiseksi kolmella biologisella laatutekijällä, kasviplankton, vesikasvit ja pohjaeläimet. Tämä julkaisu sisältää kasviplanktonin laadunvarmistusta koskevan osahankkeen kuvauksen ja tulokset sekä suositukset laadunvarmistustoimenpiteiksi. Raportissa tarkastellaan kasviplanktonanalyysin toteutusta Suomessa ja muualla Euroopassa. Tarkastelun painopisteenä ovat tulosten vertailtavuus ja siihen vaikuttavat tekijät sekä SYKEn sisä- ja rannikkovesien kasviplanktonanalyysin nykytila, valmiudet ja kehittämislinjat. Raportissa linjataan SYKEn rooli sisä- ja rannikkovesien kasviplanktonmäärityksen kansallisessa ja kansainvälisessä laadunvarmennuksessa osana vertailulaboratoriotoimintaa. Kasviplanktonin analysointi edellyttää hyvää lajintuntemusta, yhtenäisten ja hyväksyttyjen analyysimenetelmien käyttöä sekä kykyä tulkita saatuja tuloksia. Kasviplanktonmäärityksiä tehdään Suomessa viranomaisten lisäksi konsulttityönä sekä tutkimushankkeissa. On myös todennäköistä, että biologinen analyysitoiminta laajenee jatkossa useamman toimijan piiriin. VPD:n toteutuksen kannalta on tärkeää, että kasviplanktonin määritystulokset ovat mahdollisimman laajasti hyödynnettävissä ekologisen tilan luokittelussa. Tämä asettaa vaatimuksia tulosten keskinäiselle vertailtavuudelle ja laadulle ja edellyttää säännöllistä määritystulosten testaamista ja vertailua toimijoiden kesken. Suomalaiset kasviplanktontutkijat ovat olleet edelläkävijöitä laadunvarmistuksessa verkostoitumalla ja kokoontumalla vuosittain työseminaareihin, joissa on käsitelty menetelmien harmonisointia ja vertailtavuutta. Vertailulaboratoriotoiminnan tarkoituksena on vahvistaa ja koordinoida toteutettua laadunvarmennusta ja saada mahdollisimman moni kasviplanktonmäärityksiä tekevä mukaan toiminnan piiriin

Incident colorectal cancer in Lynch syndrome is usually not preceded by compromised quality of colonoscopy

Peer reviewe

Is there a need for neoadjuvant short-course radiotherapy in T3 rectal cancer with positive lymph node involvement? A single-center retrospective cohort study

Background Neoadjuvant short-course radiotherapy is used to reduce local recurrences in stage III rectal cancer. Radiotherapy is not harmless, and meticulous total mesorectal excision surgery alone has been reported to result in low local recurrence rate in favorable stage III tumors. The aim was to evaluate the effect of short-course (5 x 5 Gy) radiotherapy on the local recurrence risk in patients with pT3N1-2 rectal cancer. Materials and methods This was a retrospective study with 151 consecutive pT3N1-2M0 rectal cancer patients operated on at Helsinki University Hospital, Helsinki, Finland, during January 2005 to June 2014. Short-course radiotherapy was given to 94 patients, and 57 patients were operated on without neoadjuvant radiotherapy. The main outcome measurement was the effect of radiotherapy on local recurrence. Also, the risk factors for local recurrence were analyzed. Results Local recurrence occurred in a total 17 of 151 (11.3%) patients, 8 of 57 (14.0%) in surgery only group compared with 9 of 94 (9.6%) in radiotherapy plus surgery group (p = 0.44). In univariate Cox regression analysis, the risk factors for local recurrence were tumor location under 6 cm from the anal verge (p = 0.01), involved lateral margin (p <0.001), tumor perforation (p <0.001), and mucinous histology (p = 0.006). In multivariate analysis, risk factors were tumor location under 6 cm from anal verge (p = 0.03) and involved lateral margin (p = 0.002). Conclusion Neoadjuvant short-course radiotherapy did not affect the local recurrence risk of pT3N1-2M0 rectal cancer. Further studies with larger patient number are needed to evaluate the role of short-course radiotherapy in different T3 subgroups (3a-c) as well as in N1 and N2 cancers in separate.Peer reviewe