University of Costa Rica

About: University of Costa Rica is a education organization based out in San José, Costa Rica. It is known for research contribution in the topics: Population & Venom. The organization has 9817 authors who have published 16781 publications receiving 238208 citations. The organization is also known as: UCR & Universidad de Costa Rica.

Di- and trinuclear complexes with the mono- and dianion of 2,6-bis(phenylamino)pyridine: high-field displacement of chemical shifts due to the magnetic anisotropy of quadruple bonds.

Abstract: The monoanion of 2,6-bis(phenylamino)pyridine (HBPAP(-)) has been found to support quadruply bonded Cr(2)(4+) and Mo(2)(4+) units in Cr(2)(HBPAP)(4) (1) and Mo(2)(HBPAP)(4) (2). The corresponding dianion BPAP(2)(-) was able to stabilize the trinuclear complexes, (TBA)(2)Cr(3)(BPAP)(4) (3) and (TBA)(2)Ni(3)(BPAP)(4) (4), where TBA is the tetrabutylammonium cation. The dinuclear complexes have the typical paddlewheel configuration with Cr-Cr distances of about 1.87 A and a Mo-Mo distance of 2.0813(5) A and exhibit a high-field displacement of the corresponding N-H signals caused by the magnetic anisotropy of the quadruple bonds. For the trinuclear complexes, 3 has a linear chain of three chromium atoms arranged in an unsymmetrical fashion with two chromium atoms paired to give a quadruply bonded unit (Cr-Cr distance: 1.904(3) A) and an isolated, square planar Cr(II) unit at 2.589(3) A from the dimetal unit. On the other hand, the three nickel atoms in 4 are evenly spaced, having Ni.Ni distances of 2.3682(8) A. The trinuclear compounds show a twisted conformation with an overall torsion angle of about 30 degrees.

Bactericidal and Antiendotoxic Properties of Short Cationic Peptides Derived from a Snake Venom Lys49 Phospholipase A2

Abstract: The activities of short synthetic, nonhemolytic peptides derived from the C-terminal region of myotoxin II, a catalytically inactive phospholipase A 2 homologue present in the venom of the snake Bothrops asper , have been shown to reproduce the bactericidal activity of the parent protein. They combine cationic and hydrophobic-aromatic amino acids, thus functionally resembling the antimicrobial peptides of innate defenses. This study evaluated the antimicrobial and antiendotoxic properties of a 13-mer derivative peptide of the C-terminal sequence from positions 115 to 129 of myotoxin II, named pEM-2. This peptide (KKWRWWLKALAKK) showed bactericidal activity against both gram-positive and gram-negative bacteria. In comparison to previously described peptide variants derived from myotoxin II, the toxicity of pEM-2 toward eukaryotic cells in culture was significantly reduced, being similar to that of lactoferricin B but lower than that of polymyxin B. The all-d enantiomer of pEM-2 [pEM-2 (d)] retained the same bactericidal potency of its l-enantiomeric counterpart, but it showed an enhanced ability to counteract the lethal activity of an intraperitoneal lipopolysaccharide challenge in mice, which correlated with a significant reduction of the serum tumor necrosis factor alpha levels triggered by this endotoxin. Lethality induced by intraperitoneal infection of mice with Escherichia coli or Salmonella enterica serovar Typhimurium was reduced by the administration of pEM-2 (d). These results demonstrate that phospholipase A 2 -derived peptides may have the potential to counteract microbial infections and encourage further evaluations of their actions in vivo.

Mutation analysis of glucose-6-phosphate dehydrogenase (G6PD) variants in Costa Rica

Abstract: Glucose-6-phosphate dehydrogenase (G6PD) deficiency has previously been reported among both the black and white populations of Costa Rica. All 28 G6PD A — samples were found to be of the common G6PD A-376G/202Atype. A previously described mutation associated with nonspherocytic hemolytic anemia, G6PD Puerto Limon, was found to be due to a G→A transition at nucleotide (nt) 1192, causing a glu→lys substitution. Mutations in this region of the G6PD molecule seem invariably to be associated with chronic hemolytic anemia. G6PD Santamaria had been described previously in two unrelated white subjects. We found that both did, indeed, have the same mutations. In this variant the A→G substitution at nt 376 that is characteristic of G6PD A was present, but an A→T mutation at nt 542, apparently superimposed on the ancient G6PD A mutation, resulted in an asp→val substitution. Thus, the gain of a negative charge at amino acid 126 was counterbalanced by the loss of a charge at amino acid 181, giving rise to a variant with the G6PD A mutation but with normal electrophoretic mobility.