Akakus

Le petit massif de l’Akakus, en Libye, à faible distance du Tassili -moins de 100 km- est, comme le Tassili, constitué de pointements de grès d’âge primaire très déchiquetés par l’érosion éolienne, et de larges vallées ensablées. Il s’agit néanmoins d’une unité orogénique distincte, nettement délimitée à l’ouest : elle s’y termine en effet par une falaise abrupte, dominant la vallée du Tanezrouft, que suit la piste de Serdeles à Ghat. Les accès ne sont possibles que par l’est, où les vallées ..

Akakus

Le petit massif de l’Akakus, en Libye, à faible distance du Tassili -moins de 100 km- est, comme le Tassili, constitué de pointements de grès d’âge primaire très déchiquetés par l’érosion éolienne, et de larges vallées ensablées. Il s’agit néanmoins d’une unité orogénique distincte, nettement délimitée à l’ouest : elle s’y termine en effet par une falaise abrupte, dominant la vallée du Tanezrouft, que suit la piste de Serdeles à Ghat. Les accès ne sont possibles que par l’est, où les vallées ..

Bœuf (Préhistoire)

De nombreuses études avaient, tout au long du xixe siècle, décrit et nommé de multiples espèces ou sous-espèces de Bos. Sanson, par exemple, en dénombrait douze dans les seuls taurins. Au xxe siècle, une révision se fit : la Nomenclature en vigueur ne retient dans le sous-genre Bos, pour les animaux actuels, que trois sous-espèces (ou « types ») : le bœuf à bosse, B. indicus et deux types de « taurins », sans bosse : le B. primigenius ou bœuf à longues cornes (le longhorn) et le B. brachycero..

Different Quaternary Structures of Human RECQ1 Are Associated with Its Dual Enzymatic Activity

RecQ helicases are essential for the maintenance of chromosome stability. In addition to DNA unwinding, some RecQ enzymes have an intrinsic DNA strand annealing activity. The function of this dual enzymatic activity and the mechanism that regulates it is, however, unknown. Here, we describe two quaternary forms of the human RECQ1 helicase, higher-order oligomers consistent with pentamers or hexamers, and smaller oligomers consistent with monomers or dimers. Size exclusion chromatography and transmission electron microscopy show that the equilibrium between the two assembly states is affected by single-stranded DNA (ssDNA) and ATP binding, where ATP or ATPγS favors the smaller oligomeric form. Our three-dimensional electron microscopy reconstructions of human RECQ1 reveal a complex cage-like structure of approximately 120 Å × 130 Å with a central pore. This oligomeric structure is stabilized under conditions in which RECQ1 is proficient in strand annealing. In contrast, competition experiments with the ATPase-deficient K119R and E220Q mutants indicate that RECQ1 monomers, or tight binding dimers, are required for DNA unwinding. Collectively, our findings suggest that higher-order oligomers are associated with DNA strand annealing, and lower-order oligomers with DNA unwinding

Complex activities of the human Bloom's syndrome helicase are encoded in a core region comprising the RecA and Zn-binding domains

Bloom's syndrome DNA helicase (BLM), a member of the RecQ family, is a key player in homologous recombination (HR)-based error-free DNA repair processes. During HR, BLM exerts various biochemical activities including single-stranded (ss) DNA translocation, separation and annealing of complementary DNA strands, disruption of complex DNA structures (e.g. displacement loops) and contributes to quality control of HR via clearance of Rad51 nucleoprotein filaments. We performed a quantitative mechanistic analysis of truncated BLM constructs that are shorter than the previously identified minimal functional module. Surprisingly, we found that a BLM construct comprising only the two conserved RecA domains and the Zn2+-binding domain (residues 642–1077) can efficiently perform all mentioned HR-related activities. The results demonstrate that the Zn2+-binding domain is necessary for functional interaction with DNA. We show that the extensions of this core, including the winged-helix domain and the strand separation hairpin identified therein in other RecQ-family helicases, are not required for mechanochemical activity per se and may instead play modulatory roles and mediate protein–protein interactions

Robot-assisted versus laparoscopic pancreatoduodenectomy: a pan-European multicenter propensity-matched study

Background: The use of robot -assisted and laparoscopic pancreatoduodenectomy is increasing, yet large adjusted analyses that can be generalized internationally are lacking. This study aimed to compare outcomes after robot -assisted pancreatoduodenectomy and laparoscopic pancreatoduodenectomy in a pan-European cohort. Methods: An international multicenter retrospective study including patients after robot -assisted pancreatoduodenectomy and laparoscopic pancreatoduodenectomy from 50 centers in 12 European countries (2009-2020). Propensity score matching was performed in a 1:1 ratio. The primary outcome was major morbidity (Clavien-Dindo >= III). Results: Among 2,082 patients undergoing minimally invasive pancreatoduodenectomy, 1,006 underwent robot -assisted pancreatoduodenectomy and 1,076 laparoscopic pancreatoduodenectomy. After matching 812 versus 812 patients, the rates of major morbidity (31.9% vs 29.6%; P = .347) and 30-day/inhospital mortality (4.3% vs 4.6%; P = .904) did not differ significantly between robot -assisted pancreatoduodenectomy and laparoscopic pancreatoduodenectomy, respectively. Robot -assisted pancreatoduodenectomy was associated with a lower conversion rate (6.7% vs 18.0%; P < .001) and higher lymph node retrieval (16 vs 14; P = .003). Laparoscopic pancreatoduodenectomy was associated with shorter operation time (446 minutes versus 400 minutes; P < .001), and lower rates of postoperative pancreatic fistula grade B/C (19.0% vs 11.7%; P < .001), delayed gastric emptying grade B/C (21.4% vs 7.4%; P < .001), and a higher R0 -resection rate (73.2% vs 84.4%; P < .001). Conclusion: This European multicenter study found no differences in overall major morbidity and 30day/in-hospital mortality after robot -assisted pancreatoduodenectomy compared with laparoscopic pancreatoduodenectomy. Further, laparoscopic pancreatoduodenectomy was associated with a lower rate of postoperative pancreatic fistula, delayed gastric emptying, wound infection, shorter length of stay, and a higher R0 resection rate than robot -assisted pancreatoduodenectomy. In contrast, robot -assisted pancreatoduodenectomy was associated with a lower conversion rate and a higher number of retrieved lymph nodes as compared with laparoscopic pancreatoduodenectomy. (c) 2024 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Robot-assisted versus laparoscopic pancreatoduodenectomy:a pan-European multicenter propensity-matched study

Background: The use of robot-assisted and laparoscopic pancreatoduodenectomy is increasing, yet large adjusted analyses that can be generalized internationally are lacking. This study aimed to compare outcomes after robot-assisted pancreatoduodenectomy and laparoscopic pancreatoduodenectomy in a pan-European cohort. Methods: An international multicenter retrospective study including patients after robot-assisted pancreatoduodenectomy and laparoscopic pancreatoduodenectomy from 50 centers in 12 European countries (2009–2020). Propensity score matching was performed in a 1:1 ratio. The primary outcome was major morbidity (Clavien–Dindo ≥III). Results: Among 2,082 patients undergoing minimally invasive pancreatoduodenectomy, 1,006 underwent robot-assisted pancreatoduodenectomy and 1,076 laparoscopic pancreatoduodenectomy. After matching 812 versus 812 patients, the rates of major morbidity (31.9% vs 29.6%; P = .347) and 30-day/in-hospital mortality (4.3% vs 4.6%; P = .904) did not differ significantly between robot-assisted pancreatoduodenectomy and laparoscopic pancreatoduodenectomy, respectively. Robot-assisted pancreatoduodenectomy was associated with a lower conversion rate (6.7% vs 18.0%; P &lt; .001) and higher lymph node retrieval (16 vs 14; P = .003). Laparoscopic pancreatoduodenectomy was associated with shorter operation time (446 minutes versus 400 minutes; P &lt; .001), and lower rates of postoperative pancreatic fistula grade B/C (19.0% vs 11.7%; P &lt; .001), delayed gastric emptying grade B/C (21.4% vs 7.4%; P &lt; .001), and a higher R0-resection rate (73.2% vs 84.4%; P &lt; .001). Conclusion: This European multicenter study found no differences in overall major morbidity and 30-day/in-hospital mortality after robot-assisted pancreatoduodenectomy compared with laparoscopic pancreatoduodenectomy. Further, laparoscopic pancreatoduodenectomy was associated with a lower rate of postoperative pancreatic fistula, delayed gastric emptying, wound infection, shorter length of stay, and a higher R0 resection rate than robot-assisted pancreatoduodenectomy. In contrast, robot-assisted pancreatoduodenectomy was associated with a lower conversion rate and a higher number of retrieved lymph nodes as compared with laparoscopic pancreatoduodenectomy.</p