Determination of the Critical Concentration of Rifabutin for Susceptibility Testing Using the Proportion Method with Löwenstein-Jensen Medium against Mycobacterium Tuberculosis Isolates.

Objective: To determine the critical concentration of rifabutin (RFB) for susceptibility testing against Mycobacterium tuberculosis (Mtb) on Löwenstein-Jensen (L-J) medium using the proportion method.

Methods: We used 47 strains were used to determine the critical concentration of RFB. The microplate antimicrobial assay (MABA) was used as a reference method.

The Clinical Features and Bacteriological Characterizations of Bone and Joint Tuberculosis in China.

Bone and Joint tuberculosis (BJTB) constitutes about 10% of total extra-pulmonary TB cases. Since the BJTB is a paucibacillary condition, there has been no systematic study on the bacterial characterization, especially the epidemiological feature. Here we collected the mycobacterial clinical isolates, analyzed the clinical features and the bacteriological characteristics from 113 BJTB cases reported in China.

Expression in yeast, new substrates, and construction of a first 3D model of human orphan cytochrome P450 2U1: Interpretation of substrate hydroxylation regioselectivity from docking studies.

Background: Cytochrome P450 2U1 (CYP2U1) has been identified from the human genome and is highly conserved in the living kingdom. In humans, it has been found to be predominantly expressed in the thymus and in the brain. CYP2U1 is considered as an "orphan" enzyme as few data are available on its physiological function(s) and active site topology.

Reactions of amino acids, peptides, and proteins with oxidized metabolites of tris(p-carboxyltetrathiaaryl)methyl radical EPR probes.

Oxidation of the tris(p-carboxyltetrathiaaryl)methyl (TAM) EPR radical probe, TAMa(•), by rat liver microsomes (RLM) + NADPH, or horseradish peroxidase (HRP) + H2O2, or K2IrCl6, led to an intermediate cation, TAMa(+), which was treated with glutathione (GSH), with formation of an adduct, TAMa-SG(•), resulting from the substitution of a TAMa(•) carboxylate group with the SG group. L-α-Amino acids containing a strong nucleophilic residue (NuH), such as L-cysteine or L-histidine, also reacted with TAMa(+), with formation of radical adducts TAMa-Nu(•) in which a carboxylate group of TAMa(•) was replaced with Nu. Other less nucleophilic L-α-amino acids, such as L-arginine, L-serine, L-threonine, L-tyrosine, or L-aspartate, as well as the tetrapeptide H-(Gly)4-OH, reacted with TAMa(+) via their α-NH2 group, with formation of an iminoquinone methide, IQMa, deriving from an oxidative decarboxylation and amination of TAMa(•).

Toward stable electron paramagnetic resonance oximetry probes: synthesis, characterization, and metabolic evaluation of new ester derivatives of a tris-(para-carboxyltetrathiaaryl)methyl (TAM) radical.

Tris(p-carboxyltetrathiaaryl)methyl (TAM) radicals, such as 1a ("Finland" radical), are useful EPR probes for oximetry. However, they are rapidly metabolized by liver microsomes in the presence of NADPH, with the formation of diamagnetic quinone-methide metabolites resulting from an oxidative decarboxylation of one of their carboxylate substituents. In an effort to obtain TAM derivatives potentially more metabolically stable in vivo, we have synthesized four new TAM radicals in which the carboxylate substituents of 1a have been replaced with esters groups bearing various alkyl chains designed to render them water-soluble.

First combined in vivo X-ray tomography and high-resolution molecular electron paramagnetic resonance (EPR) imaging of the mouse knee joint taking into account the disappearance kinetics of the EPR probe.

Although laboratory data clearly suggest a role for oxidants (dioxygen and free radicals derived from dioxygen) in the pathogenesis of many age-related and degenerative diseases (such as arthrosis and arthritis), methods to image such species in vivo are still very limited. This methodological problem limits physiopathologic studies about the role of those species in vivo, the effects of their regulation using various drugs, and the evaluation of their levels for diagnosis of degenerative diseases. In vivo electron paramagnetic resonance (EPR) imaging and spectroscopy are unique, noninvasive methods used to specifically detect and quantify paramagnetic species.

Mongoliicoccus roseus gen. nov., sp. nov., an alkaliphilic bacterium isolated from a haloalkaline lake.

Two pink, non-motile, aerobic, alkaliphilic, halotolerant, Gram-negative cocci, designated MIM28(T) and MIM29, were isolated from the surface water of a haloalkaline lake on the Mongolia Plateau. The isolates grew optimally at 30-33 °C, at pH 8-9 and with 3-4 % (w/v) NaCl. The isolates were chemoheterotrophic and could assimilate carbohydrates, organic acids and amino acids.

Role of arginine guanidinium moiety in nitric-oxide synthase mechanism of oxygen activation.

Nitric-oxide synthases (NOS) are highly regulated heme-thiolate enzymes that catalyze two oxidation reactions that sequentially convert the substrate L-Arg first to N(omega)-hydroxyl-L-arginine and then to L-citrulline and nitric oxide. Despite numerous investigations, the detailed molecular mechanism of NOS remains elusive and debatable. Much of the dispute in the various proposed mechanisms resides in the uncertainty concerning the number and sources of proton transfers.