Evidence for a Bis(Elongated s)-Dihydrideborate Coordinated to Osmium

The formation and Atoms in Molecules (AIM) analysis of osmium(IV) and osmium(II) complexes containing dihydrideborate groups and primary aminoborane ligands are reported. Complex OsH6(PiPr3)2 (1) loses a hydrogen molecule and the resulting unsaturated OsH4(PiPr3)2 species coordinates 9-borabicycle[3.3.1]nonane (HBbn) and pinacolborane (HBpin) to give the dihydrideborate derivatives OsH3{¿2-H, H-(H2BR2)}(PiPr3)2 (BR2 = Bbn (2), Bpin (3)). The bonding situation in these compounds and in the related osmium(II) derivative Os(Bcat){¿2-H, H-(H2Bcat)}(CO)(PiPr3)2 (4) (HBcat = catecholborane) has been analyzed by the AIM method. The Laplacian distributions in the Os-H-B plane exhibit a four-membered cyclic topology possessing two Os-H and two B-H bond critical points associated with one OsHHB ring critical point, which resembles that found for B2H6. The tetrahydride OsH4(PiPr3)2 also coordinates catecholborane, which initially affords OsH3{¿2-H, H-(H2Bcat)}(PiPr3)2 (5). In contrast to 2 and 3, complex 5 reacts with a second molecule of HBcat to give the elongated s-borane-{bis(elongated s)-dihydrideborate}-osmium(II) derivative OsH(¿3-H2Bcat)(¿2-HBcat)(PiPr3)2 (6). Complexes 5 and 6 have been also analyzed via the AIM method. Complex 5 displays the same topology as complexes 2-4. However, the OsH2B unit of 6 shows, besides the Os-H and B-H bond critical points, an additional Os-B bond critical point, which is associated with a bond path running between these atoms. This double triangular topology is completed with the respective ring critical points. Reactions of 1 with dimethylamine-borane (H3B·NHMe2) and tert-butylamine-borane (H3B·NH2 tBu) give OsH2(¿2:¿2-H2BNR2)(PiPr3)2 (NR2 = NMe2 (7), NHtBu (8)). The AIM analyses of 7 and 8 also reveal the occurrence of an Os-B bond critical point associated with a bond path running between those atoms. However, neither Os-H bond critical points nor bond paths are observed in the latter species

Biometrics of the Posterior Communicating Artery and the Posterior Cerebral Artery in its Precommunicating Segment (P1) of the Arterial Circle of Brain (Willis)

Indexación: ScieloEl conocimiento anatómico y clínico preciso del círculo arterial del cerebro, se hace cada vez más necesario, por la compleja relación neural que presentan las diversas arterias que entran en su formación y además por su gran variabilidad. Utilizamos 36 encéfalos humanos frescos, provenientes de especímenes autopsiados adultos, cuyos datos bioantropológicos fueron previamente registrados. El calibre de las aa. comunicantes posteriores fue, en promedio, de 1,08 mm (DE 0,45 ) en ambos lados y su longitud de 17,51 mm( DE 7,9) en el lado derecho y de 16,9 mm (DE 8,0 ) en el lado izquierdo. La ACP en el segmento P1 presentó un calibre de 2,56 mm (DE 077) en el lado derecho y de 2,32 mm (DE 0,64) en el lado izquierdo. La longitud de estas arterias correspondió a 9,43 mm (DE 8,92) en el lado derecho y de 8,82 mm (DE 7,33 ) en el lado izquierdo. Las dimensiones observadas demuestran variabilidad que consideramos interesante de considerar en la anatomía quirúrgica.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-95022006000500015&lang=p

Characteristics of Early-Onset vs Late-Onset Colorectal Cancer: A Review.

The incidence of early-onset colorectal cancer (younger than 50 years) is rising globally, the reasons for which are unclear. It appears to represent a unique disease process with different clinical, pathological, and molecular characteristics compared with late-onset colorectal cancer. Data on oncological outcomes are limited, and sensitivity to conventional neoadjuvant and adjuvant therapy regimens appear to be unknown. The purpose of this review is to summarize the available literature on early-onset colorectal cancer. Within the next decade, it is estimated that 1 in 10 colon cancers and 1 in 4 rectal cancers will be diagnosed in adults younger than 50 years. Potential risk factors include a Westernized diet, obesity, antibiotic usage, and alterations in the gut microbiome. Although genetic predisposition plays a role, most cases are sporadic. The full spectrum of germline and somatic sequence variations implicated remains unknown. Younger patients typically present with descending colonic or rectal cancer, advanced disease stage, and unfavorable histopathological features. Despite being more likely to receive neoadjuvant and adjuvant therapy, patients with early-onset disease demonstrate comparable oncological outcomes with their older counterparts. The clinicopathological features, underlying molecular profiles, and drivers of early-onset colorectal cancer differ from those of late-onset disease. Standardized, age-specific preventive, screening, diagnostic, and therapeutic strategies are required to optimize outcomes

PARAMESH: two dimensional unstructured parallel mesh generation program

Preprin

PARAMESH: two dimensional unstructured parallel mesh generation program

Preprin

Randomized clinical trial to assess the protective efficacy of a Plasmodium vivax CS synthetic vaccine.

A randomized, double-blind, controlled vaccine clinical trial was conducted to assess, as the primary outcome, the safety and protective efficacy of the Plasmodium vivax circumsporozoite (CS) protein in healthy malaria-naïve (phase IIa) and semi-immune (phase IIb) volunteers. Participants (n = 35) were randomly selected from a larger group (n = 121) and further divided into naïve (n = 17) and semi-immune (n = 18) groups and were immunized at months 0, 2, and 6 with PvCS formulated in Montanide ISA-51 adjuvant or placebo (adjuvant alone). Specific antibodies and IFN-γ responses to PvCS were determined as secondary outcome; all experimental volunteers developed specific IgG and IFN-γ. Three months after the last immunization, all participants were subjected to controlled human malaria infection. All naive controls became infected and drastic parasitemia reduction, including sterile protection, developed in several experimental volunteers in phase IIa (6/11) (54%, 95% CI 0.25-0.84) and phase IIb (7/11) (64%, 95% CI 0.35-0.92). However, no difference in parasitemia was observed between the phase IIb experimental and control subgroups. In conclusion, this study demonstrates significant protection in both naïve and semi-immune volunteers, encouraging further PvCS vaccine clinical development. Trial registration number NCT02083068. This trial was funded by Colciencias (grant 529-2009), NHLBI (grant RHL086488 A), and MVDC/CIV Foundation (grant 2014-1206)

Consenso colombiano de atención, diagnóstico y manejo de la infección por SARS-COV-2/COVID-19 en establecimientos de atención de la salud Recomendaciones basadas en consenso de expertos e informadas en la evidencia

The “Asociación Colombiana de Infectología” (ACIN) and the “Instituto de Evaluación de Nuevas Tecnologías de la Salud” (IETS) created a task force to develop recommendations for Covid 19 health care diagnosis, management and treatment informed, and based, on evidence. Theses reccomendations are addressed to the health personnel on the Colombian context of health services. © 2020 Asociacion Colombiana de Infectologia. All rights reserved