Purification and characterization of two beta-glucosidases from the thermophilic fungus Thermoascus aurantiacus.

beta-Glucosidase from the fungus Thermoascus aurantiacus grown on semi-solid fermentation medium (using ground corncob as substrate) was partially purified in 5 steps--ultrafiltration, ethanol precipitation, gel filtration and 2 anion exchange chromatography runs, and characterized. After the first anion exchange chromatography, beta-glucosidase activity was eluted in 3 peaks (Gl-1, Gl-2, Gl-3). Only the Gl-2 and Gl-3 fractions were adsorbed on the gel matrix. Gl-2 and Gl-3 exhibited optimum pH at 4.5 and 4.0, respectively. The temperature optimum of both glucosidases was at 75-80 degrees C. The pH stability of Gl-2 (4.0-9.0) was higher than Gl-3 (5.5-8.5); both enzyme activities showed similar patterns of thermostability. Under conditions of denaturing gel chromatography the molar mass of Gl-2 and Gl-3 was 175 and 157 kDa, respectively. Using 4-nitrophenyl beta-D-glucopyranoside as substrate, Km values of 1.17 +/- 0.35 and 1.38 +/- 0.86 mmol/L were determined for Gl-2 and Gl-3, respectively. Both enzymes were inhibited by Ag+ and stimulated by Ca2+.

Structural characterization, kinetic studies, and in vitro biological activity of new cis-diamminebis-cholylglycinate(O,O') Pt(II) and cis-diamminebis-ursodeoxycholate(O,O') Pt(II) complexes.

The complexes cis-diamminebis-cholylglycinate (O,O') [Pt(II) C(52)H(90)N(4)O(12)Pt, for convenience referred to as Bamet-R1] and cis-diamminebis-ursodeoxycholate (O,O') Pt(II) (C(48)H(84)N(2)O(8)Pt, Bamet-UD2) were prepared. The structural integrity of the compounds was confirmed by elemental analysis, FT-IR, NMR, FAB-MS, and UV spectroscopies. The kinetic study of both compounds was accomplished by combining the conductivity measurement and those of the analysis of the electronic spectra in aqueous solution for NaCl concentrations of 4 mM (similar to cytoplasmatic concentration), 150 mM (similar to plasmatic concentration), and 500 mM. In water, the compound Bamet-R1 showed a half-life, t(1/2), of 3.0 h. This compound forms the chelate species through loss of a ligand, and the other one acts as a bidentate ligand. Ring opening in the presence of chloride ion was produced with a k(Cl)()-of 0.25 M(-)(1) h(-)(1). The half-life of Bamet-UD2 in aqueous solution was 3.2 h. However, since this species is not able to chelate and has a lower degree of solubility in the presence of chloride ion, its kinetic behavior was very different from that of the other compound. We consider this to be of great interest with regards to its cytostatic activity. All kinetic measurements were performed under pseudo-first-order conditions, and a pseudo-first-order behavior was found. The antitumoral effect of Bamet-UD2 on several cell lines derived from rat hepatoma, human hepatoma, mouse leukemia, and human colon carcinoma was found to be, in general, similar to that of cisplatin, but higher than that observed for Bamet-R1.

Lesion hepatica secundaria al uso de alfametildopa: informe de tres casos y revision de la literatura. / Secondary hepatic injury to the use of alphamethyldopa: report of 3 cases and literature review

En la literatura se tiene conocimiento de multiples casos de hepatopatia secundaria a la ingestion de alfametildopa, la lesion varia entre elevacion transitoria de aminotransferasas hasta hepatitis fulminante y muerte del enfermo. Al revisar la literatura al alcance se obtuvo informacion de 198 pacientes con esta complicacion. Se presentan los casos de tres pacientes con lesion hepatica en quienes la unica causa de la misma fue la ingestion de alfametildopa. Aun no se conoce exactamente cual es el mecanismo patogenico del farmaco, pero por la evolucion de los pacientes y la revision de la literatura se proponen los dos siguientes: 1. Alteraciones inmunologicas en el huesped. 2. Probable produccion de factores inmunogenos por la incorporacion del farmaco o sus metabolitos a la membrana celular del hepatocito