50,404 research outputs found
The constant proportion of grana and stroma lamellae in plant chloroplasts
No full textThe relative proportion of stroma lamellae and grana end membranes was determined from electron micrographs of 58 chloroplasts from 21 different plant species. The percentage of grana end membranes varied between 1 and 21% of the total thylakoid membrane indicating a large variation in the size of grana stacks. By contrast the stroma lamellae account for 20.3 +/- 2.5 (SD)% of the total thylakoid membrane. A plot of percentage stroma lamellae against percentage of grana end membranes fits a straight line with a slope of zero showing that the proportion of stroma lamellae is independent of the size of the grana stacks. That stroma lamellae account for about 20% of the thylakoid membrane is in agreement with fragmentation and separation analysis (Gadjieva et al. Biochim. Biophys. Acta 144: 92-100, 1999). Chloroplasts from spinach, grown under high or low light, were fragmented by sonication and separated by countercurrent distribution into two vesicle populations originating from grana and stroma lamellae plus end membranes, respectively. The separation diagrams were very similar lending independent support for the notion that the proportion of stroma lamellae is constant. The results are discussed in relation to the composition and function of the chloroplast in plants grown under different environmental conditions, and in relation to a recent quantitative model for the thylakoid (Albertsson, Trends Plant Sci. 6: 349-354, 2001)
Two cases of 5-fluorouracil toxicity linked with gene variants in the DPYD gene
No full textObjectives: Dihydropyrimidine dehydrogenase (DPD) is the initial rate-limiting enzyme in endogenous pyrimidine catabolism and is responsible for the reduction of the pyrimidine analog 5-fluorouracil (5-FU). DPD deficiency is known to cause potentially lethal toxicity in patients receiving 5-FU. We here report a frequency analysis of one of the major splice-site mutations in the DPDY gene, and further two new DPYD gene variants. Design and methods: Restriction fragment length polymorphisin (RFLP) and DNA sequence analysis were performed on genomic DNA and mRNA. Results: In 400 patients that were diagnosed with cancer and were eligible for 5-FU treatment, 14 patients were found to be heterozygous for the splice-site mutation DPYD IVS14+1Gandgt;A, which corresponds to a population frequency of 3.5%. Two novel variants in the DPYD gene were identified. The first case was heterozygous for DPYD c. 1796Tandgt;C (p.M599T). In the second case, we observed heterozygosity for the splice-site mutation DPYD IVS14+17Aandgt;G. Conclusions: We report two new DPYD gene variants, of which DPYD c. 1796Tandgt;C is potentially pathogenic, whereas DPYD IVS14+17Aandgt;G is suggested as a variant without clinical significance.Original Publication: Anna Ofverholm, Eva Arkblad, Stanko Skrtic, Per Albertsson, Emman Shubbar and Charlotta Enerbäck, Two cases of 5-fluorouracil toxicity linked with gene variants in the DPYD gene, 2010, CLINICAL BIOCHEMISTRY, (43), 3, 331-334. http://dx.doi.org/10.1016/j.clinbiochem.2009.09.024 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/</p
Levosimendan neither improves nor worsens mortality in patients with cardiogenic shock due to ST-elevation myocardial infarction
No full textElmir Omerovic, Truls R&aring;munddal, Per Albertsson, Mikael Holmberg, Per Hallgren, Jan Boren, Lars Grip, G&ouml;ran MatejkaDepartment of Cardiology, Sahlgrenska University Hospital, Gothenburg, SwedenBackground: The aim of this study was to evaluate the effect of levosimendan on mortality in cardiogenic shock (CS) after ST elevation myocardial infarction (STEMI).Methods and results: Data were obtained prospectively from the SCAAR (Swedish Coronary Angiography and Angioplasty Register) and the RIKS-HIA (Register of Information and Knowledge about Swedish Heart Intensive Care Admissions) about 94 consecutive patients with CS due to STEMI. Patients were classified into levosimendan-mandatory and levosimendan-contraindicated cohorts. Inotropic support with levosimendan was mandatory in all patients between January 2004 and December 2005 (n = 46). After the SURVIVE and REVIVE II studies were presented, levosimendan was considered contraindicated and was not used in consecutive patients between December 2005 and December 2006 (n = 48). The cohorts were similar with respect to pre-treatment characteristics and concomitant medications. There was no difference in the incidence of new-onset atrial fibrillation, in-hospital cardiac arrest and length of stay at the coronary care unit. There was no difference in adjusted mortality at 30 days and at one year.Conclusion: The use of levosimendan neither improves nor worsens mortality in patients with CS due to STEMI. Well-designed randomized clinical trials are needed to define the role of inotropic therapy in the treatment of CS.Keywords: shock, myocardial infarction, inotropic agents, heart failure, pharmacolog
A remarkable constancy in the relative amount of stroma lamellae of chloroplasts from plants, and its functional significance
No full textA model is presented which gives a quantitative picture of the distribution of the photosynthetic components in the thylakoid membrane of higher plants. The model is based on fragmentation and separation analysis together with microscopy. A salient feature of the model is that over 80 per cent of the pigments are located in the grana where the two photosystems 1 and 2 produce oxygen, NADPH and ATP by the linear electron transport pathway while the stroma lamellae, which harbour less than 20 per cent of the pigments, carry out Photosystem 1 mediated cyclic electron transport coupled to ATP production. This arrangement derives from the observation that more pigments are associated with Photosystem 1 which therefore captures more quanta than Photosystem 2. The excess pigments associated with Photosystem 1 are suggested to be located in the stroma lamellae. Tentative numbers of the different photosystem and cytochrome b.f. complexes located in the different domains of the thylakoid membrane will be presented
Author Self-Citation in the Turkish Otorhinolaryngology Literature
No full textObjective:To evaluate the prevalence and other characteristics of author self-citations in six Turkey-originated general otorhinolaryngology (ORL) journals of Turkish ORL literature.Methods:A total of 970 articles published in six Turkey-originated general ORL journals (ENT Updates, Journal of Ear Nose Throat and Head Neck Surgery, KBB-Forum, Praxis of Otorhinolaryngology, The Turkish Journal of Ear Nose and Throat, and Turkish Archives of Otorhinolaryngology) in 2016-2020 were analyzed for author self-citations. The association between author self-citations and journal types, study types, study topics, country of origin, and compatibility with the topic were also evaluated.Results:There were 265 author self-citations (0.273 per article) which corresponded to 1.36% of all citations. There was no significant difference between the journal types, study topics, and origin of the studies in terms of mean self-citation values per study, whereas case reports had significantly lower self-citations than review and original investigations. There were three citations (1.1%) that were irrelevant to the study topic.Conclusion:To the best of our knowledge, this is the first study that investigated the practice of author self-citation in Turkish ORL literature. Author self-citation rate in the Turkish-originated general ORL journals was found remarkably lower than the medical literature, whereas the self-citations were found compatible with the study topic to a very large extent. Members of the scientific community including authors, readers, and journal editors should be cautious regarding the unethical practices of self-citations
Applicativo web per audioguide - HooRMI Author
No full textHooRMI Author è la parte da content creator del progetto HooRMI.
La dissertazione si concentra sul funzionamento HooRMI Author, ovvero di come viene permesso all'utente di produrre contenuti video basati sulla propria posizione acquisita tramite tecnologia Plus code e caricarli sul proprio canale Youtube. I contenuti risulteranno pronti per essere selezionati e fruiti dai turisti, grazie alla profonda personalizzazione dei metadati associati ad ogni clip
The contribution of photosynthetic pigments to the development of biochemical separation methods: 1900-1980
No full textThe role of photosynthetic pigments in the development of separation methods in biochemistry during the period 1900-1980 is described beginning with M. Tswett who introduced separation of chlorophylls and carotenoids on columns and coined the term chromatography in 1906. In Uppsala, T. Svedberg developed the ultracentrifuge in the 1920s. A. Tiselius improved electrophoresis in the 1930s and developed chromatography of proteins in the 1940s and 1950s. Others of `The Uppsala school in separation science' include J. Porath, P. Flodin and S. Hjertén who further developed various gel chromatographic methods. Hjertén introduced free zone electrophoresis in narrow tubes, a forerunner of capillary electrophoresis. Two proteins, phycoerythrin and phycocyanin, were used as test substances in all these methodological studies. Aqueous two-phase partitioning as a separation method was introduced in 1956 by the author. In this work, chloroplast particles were used, and the method was applied for the separation and purification of intact chloroplasts, inside-out thylakoid vesicles and plasma membranes. My research was carried out in cooperation with G. Blomquist, G. Johansson, C. Larsson, B. Andersson and H.-E. Akerlund during a 20-year period, 1960-1980
Sectoral allocation by gender of Latin American workers over the liberalization period of the 1990s
No full textThe recent restructuring of Latin American economies has renewed interest in the effects of trade liberalization, on labor markets, and on the gender division of labor. The author does not attempt to establish casuality between economic reforms, and the types of jobs that men and women hold. Instead, she provides a detailed description of the trends in male, and female formal, and informal sector participation during the economic reform period in Argentina, Brazil, and Costa Rica. The author first compares the gender composition of the formal, informal wage, and self-employment sectors in a year before reforms (1988 for Argentina, 1989 for Brazil, and Costa Rica), and a year after reforms implementation (1997 for Argentina, 1995 for Brazil and Costa Rica). Although women continued to be more likely than men to work in the informal wage sector, there is no trend of"masculinization"or"feminization"of the informal sector, or any other. Instead, in Argentina men have overtaken women as the most prevalent workers in the informal wage sector, while in Brazil, the opposite has occurred (as men move into self-employment). In Costa Rica there have been no statistical, observable changes. The author then considers the distribution across sectors within each gender group, to identify whether men, and women are more likely to select different sectors in the post-reform period relative to the pre-reform period. Among both men, and women in all three countries (except Brazilian men), workers have become more likely to hold informal wage jobs, and less likely to hold formal sector jobs. Trends in human capital accumulation explain these changes for both men, and women, while changes in gender roles, primarily in homecare and marriage, do not seem to have an effect.Health Monitoring&Evaluation,Labor Policies,Population&Development,Public Health Promotion,Environmental Economics&Policies,Health Monitoring&Evaluation,Environmental Economics&Policies,Population&Development,Banks&Banking Reform,Work&Working Conditions
Number of 3-grams per author (in thousands).
No full textNumber of 3-grams per author (in thousands).</p
Production, productivity per author and per age group of authors of new Siluriformes species descriptions.
No full text<p>Production, black columns, y1 axis; Productivity per author, grey columns, y2 axis; Productivity per age group, striped columns, y2 axis.</p
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