999 resultados para 331.1
Resumo:
DSDP North Atlantic Site 608 yielded an excellent Miocene pelagic section which affords a further opportunity for elucidating the chronology of the calcareous nannofossil succession in the framework of magnetostratigraphic control. Most of the conventional (zonal) markers have been documented for this site and some of the earlier results are confirmed and refined. In addition several unconventional and less known markers have been added. The first two are the highest (last) occurrence of Sphenolithus delphix and Sphenolithus capricornutus at 23.6 Ma, which is immediately above the Oligocene-Miocene boundary as identified by the last occurrence of Reticulofenestra bisecta at 23.7 Ma. The next unconventional datum is the highest (last) occurrence of Ilselithina fusa at 22.8 Ma, which is also the highest (last) occurrence of Helicosphaera recta. Calcidiscus tropicus' lowest (first) occurrence is at 19.5 Ma, which is also the lowest occurrence of Sphenolithus belemnos, and Calcidiscus leptoporus' lowest (first) occurrence coincides with that of Sphenolithus heteromorphus at 18.5 Ma. Sphenolithus dissimilis' highest (last) occurrence is at 18.2 Ma and the Calcidiscus premacintyrei lowest (first) and highest (last) occurrences are, respectively, at 17.7 and 11.7 Ma. Discoaster braarudii occurs from 11.6 to 11.3 Ma and its highest (last) occurrence corresponds to that of Cyclicargolithus floridanus. Minylitha convallis occurs from 9.0 to 6.9 Ma. Within the range of Minylitha, at 8.0 Ma, a major shift occurs in reticulofenestrid placoliths from dominantly large (Reticulofenestra pseudoumbilicus) and medium size (Reticulofenestra minutula) species below to significant numbers of very small species (Dictyococcites productus and Gephyrocapsa) above. This is interpreted to be a major, though perhaps seasonal, change of productivity of the North Atlantic at Site 608. A new genus and species Cryptococcolithus takayamae, is described and a variety, Reticulofenestra pseudoumbilicus var. amplus is identified.
Resumo:
Human adrenomedullin (AM) is a 52-amino acid peptide belonging to the calcitonin peptide family, which also includes calcitonin gene-related peptide (CGRP) and AM2. The two AM receptors, AM(1) and AM(2), are calcitonin receptor-like receptor (CL)/receptor activity-modifying protein (RAMP) (RAMP2 and RAMP3, respectively) heterodimers. CGRP receptors comprise CL/RAMP1. The only human AM receptor antagonist (AM(22-52)) is a truncated form of AM; it has low affinity and is only weakly selective for AM(1) over AM(2) receptors. To develop novel AM receptor antagonists, we explored the importance of different regions of AM in interactions with AM(1), AM(2), and CGRP receptors. AM(22-52) was the framework for generating further AM fragments (AM(26-52) and AM(30-52)), novel AM/alphaCGRP chimeras (C1-C5 and C9), and AM/AM(2) chimeras (C6-C8). cAMP assays were used to screen the antagonists at all receptors to determine their affinity and selectivity. Circular dichroism spectroscopy was used to investigate the secondary structures of AM and its related peptides. The data indicate that the structures of AM, AM2, and alphaCGRP differ from one another. Our chimeric approach enabled the identification of two nonselective high-affinity antagonists of AM(1), AM(2), and CGRP receptors (C2 and C6), one high-affinity antagonist of AM(2) receptors (C7), and a weak antagonist selective for the CGRP receptor (C5). By use of receptor mutagenesis, we also determined that the C-terminal nine amino acids of AM seem to be responsible for its interaction with Glu74 of RAMP3. We provide new information on the structure-activity relationship of AM, alphaCGRP, and AM2 and how AM interacts with CGRP and AM(2) receptors.
Resumo:
The Arctic is responding more rapidly to global warming than most other areas on our planet. Northward flowing Atlantic Water is the major means of heat advection towards the Arctic and strongly affects the sea ice distribution. Records of its natural variability are critical for the understanding of feedback mechanisms and the future of the Arctic climate system, but continuous historical records reach back only ~150 years. Here, we present a multidecadal scale record of ocean temperature variations during the last 2000 years, derived from marine sediments off Western Svalbard (79°N). We find that early-21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic Amplification of global warming.
Resumo:
Rezension von: Siegfried Bernfeld: Sämtliche Werke in 16 Bänden. Band 1: Theorien des Jugendalters. Hrsg. v. Ulrich Herrmann. Weinheim/Basel: Beltz 1992, 306 S.
Resumo:
This study aimed at evaluating the functional activation and activating receptors expression on resting, short- and long-term NK and NK-like T cells from blood of ovarian neoplasia patients. Blood from patients with adnexal benign alterations (n = 10) and ovarian cancer (grade I-IV n = 14) were collected after signed consent. Effector cells activation was evaluated by the expression of the CD107a molecule. Short-term culture was conducted overnight with IL-2 and long-term culture for 21 days, by a method designed to expand CD56(+) lymphocytes. Short-term culture significantly increased NK cells activation compared to resting NK cells (p<0.05), however, the long-term procedure supported an even higher increase (p<0.001). Resting NK-like T cells showed poor activation, which was not altered by the culture procedures. The long-term culture effectively increased the expression of the activating receptors on NK and NK-like T cells, either by increasing the number of cells expressing a given receptor and/or by up-regulating their expression intensity. As a conclusion, the long-term culture system employed, resulted in a high number of functional NK cells. The culture system was particularly efficient on the up-regulation of NKp30 and DNAM-1 receptors on NK cells.