102,081 research outputs found
Molecular elements of ion permeation and selectivity within calcium channels
No full textVoltage-dependent calcium channels are located in the plasma membrane and form a highly selective conduit by which Ca2+ ions enter all excitable cells and some nonexcitable cells. Extensive characterization studies have revealed the existence of one low (T) and five high-voltage-activated calcium channel types (L, N, P, Q, and R). The high voltage-activated calcium channels have been found to exist as heteromultimers, consisting of an alpha(1), beta, alpha(2)/delta, and gamma subunit. Molecular cloning has revealed the existence of 10 channel transcripts, and expression of these cloned calcium channel genes has shown that basic voltage-activated calcium channel function is strictly carried by the corresponding a, subunits. In turn, the auxiliary subunits serve to modulate calcium channel function by altering the voltage dependence of channel gating, kinetics, and current amplitude, thereby creating a likelihood for calcium channels with multiple properties. Although for calcium channels to be effective, Ca2+ ions must enter selectively through the pore of the alpha(1)-subunit, bypassing competition with other extracellular ions. The structural determinants of this highly selective Ca2+ filter reside within the four glutamic acid residues located at homologous positions within each of the four pore-forming segments. Together, these residues form a single or multiple Ca2+ affinity site(s) that entrap calcium ions, which are then electrostatically repulsed through the intracellular opening of the pore. This mechanism of high-selectivity calcium filtration, the spatial arrangement of pore glutamic acid residues; and the coordination chemistry of calcium binding are discussed in this review
Growth and nutritional trials on transgenic Nile tilapia containing an exogenous fish growth hormone gene
No full textIn a long-term growth trial, transgenic tilapia Oreochromis niloticus L. showed a 2·5-fold
increase in growth compared with non-transgenic siblings. At 7 months, mean mass of
transgenic tilapia was 653 g compared with 260 g for non-transgenic siblings. A significant
increase (P<0·01) in head : total length ratio, viscera-somatic index and hepato-somatic index
was observed in transgenic fish. Female gonado-somatic index (IG) was found to be lower in
transgenics than non-transgenic siblings in both mixed and separate culture conditions.
Transgenic male IG values were found to be higher in mixed culture and lower in separate
culture than that of their non-transgenic siblings. Food conversion efficiency was more than
20% greater in the transgenic fish. In a second shorter-term growth performance trial, the
transgenic fish grew to about four times the size of their non-transgenic siblings. A digestibility
trial suggested that transgenic tilapia were more efficient utilizers of protein, dry matter and
energy. Apparent digestibility of protein and apparent energy digestibility were higher in the
transgenic fish
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
ChemInform Abstract: Dicobalt Hexacarbonyl Derivatives of Chiral Acetylenes.
No full text(mu(2)-RC(2)R')Co-2(CO)(6) complexes are prepared where R not equal R' and one of these substituents is a chiral organic group. The structures of the 11 complexes (10 new) range from the simplest possible chiral acetylenic hydrocarbon derivative (S-3-methyl-1-pentyne 1a) to ethynylsteroid (1f, 1g, 1h) and ethynylcodeine (1i, 1j, 1k) derivatives. The CD spectra are reported and the results are analysed in terms of a quadrant rule. The CD spectra show that in all complexes the Co-2(CO)(6) fragment of the molecule gets chirally perturbed. The reasons for the chiral perturbation include apolar repulsing (dominant for the hydrocarbon acetylenes) and polar attractive (''autosolvation''; dominant for acetylenes with polar hetero-atom containing substituents) forces
Recommended from our members
3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
2020 healthcare workers flu vaccination during covid-19: the experience of Udine University Hospital
No full textBackground: To prevent flu spread, Italian healthcare workers (HCWs) are annually recommended and given free flu vaccination. This measure of healthcare system protection resulted to be fundamental during COVID-19 pandemic to prevent staff shortage issue. Being the minimum coverage target set at 75%, we decided to evaluate vaccination adherence among HCWs at Udine University hospital.
Methods: The 2020 vaccination campaign started 4 weeks earlier than usual and was based on a multiple offer strategy including a daily-dedicated clinic, in-ward administrations along with wide vaccination agenda promotion within hospital. The prevalence and the characteristics of vaccinated HCWs were compared with the same 2019 data.
Results: During 2020, 1868 out of 3839 (48.7%) of HCWs were vaccinated, compared to 29.1% in 2019 (p < 0.0001). Doctors and residents were the most vaccinated categories in both years, being respectively 64.7% and 67.2% in 2020 vs 45.0% and 52.4% in 2019 (p < 0.0001). Midwives showed the best improvement in coverage passing from 44.4% to 20.4% (p = 0.0096). HCWs working in emergency areas and intensive care unit reached the highest adherence in 2020 (61.3%) and the best improvement compared to 2019 as well (37.9%; p < 0.0001).
Conclusions: Even if the target was not reached, strategies adopted for 2020 vaccination campaign significantly increased HCWs adherence. COVID-19 contribution in this achievement cannot be ruled out, possibly representing a strong reinforcing element for HCWs awareness towards infectious disease prevention.
Key messages: Despite the improvement in vaccination adherence, HCWs flu vaccination coverage still remains a concerning issue to be addressed. Increased flu shot adherence reached during COVID-19 pandemic should be not only a target to be maintained but even improved next year getting closer to herd immunity
- …
