The susceptibility of Mycobacterium tuberculosis to isoniazid and the Arg-->Leu mutation at codon 463 of katG are not associated

A mutation (CCG-->CTG [Arg-->Leu]) in codon 463 of katG (catalase peroxidase) of Mycobacterium tuberculosis has been found in isoniazid (INH)-resistant strains. A PCR restriction endonuclease analysis to detect this mutation was applied to 395 M. tuberculosis isolates from patients in The Netherlands. The proportion of isolates with a detectable mutation was 32% (32 out of 100) and 29% (85 out of 295) among INH-susceptible isolates and INH-resistant or -intermediate isolates, respectively. Sequencing of five INH-susceptible isolates with such mutations showed that all five had the Arg463Leu mutation. We conclude that the Arg463Leu mutation of katG of M. tuberculosis is not a reliable indicator of INH resistance.     

Differentiating moderate and severe depression using the Montgomery-Asberg depression rating scale (MADRS)

BACKGROUND: MADRS cut-off scores for moderate and severe depression were estimated in relation to the Hamilton Depression Rating Scale (HAMD(17)) and the Clinical Global Impressions Scale (CGI). METHOD: HAMD(17), MADRS, and CGI ratings from patients with major depression (DSM-IV) were analyzed (N=85). Receiver operating characteristics (ROC) curves were applied. RESULTS: Mean age was 51.4+/-14.5 years, 69% were female. Mean MADRS scores were 23.4+/-13.2, HAMD(17), MADRS, and CGI scores were highly correlated (r>0.85; P<0.0001). Best separation between moderate and severe depression according to CGI criteria was achieved with a MADRS score of 31 (sensitivity 93.5%, specificity 83.3%). LIMITATIONS: Studies to validate severity gradations including DSM-IV or ICD-10 diagnostic severity categories are recommended. CONCLUSIONS: Empirically based MADRS cut-off scores to separate moderate from severe depression on the basis of HAMD(17) and CGI severity ratings in patients with major depression were yielded.     

Role of the alpAB proteins and lipopolysaccharide in adhesion of Helicobacter pylori to human gastric tissue

The attachment of the bacterial pathogen Helicobacter pylori (H. pylori) to gastric epithelial cells is commonly believed to be required for an efficient and persistent colonization of the human stomach as well as for host cell trans-membrane signaling. In the past, several putative adhesins were postulated, including the outer membrane proteins AlpAB and the bacterial lipopolysaccharide (LPS) presenting oligomeric Lewis x (Le(x)) sugar components. We investigated the AlpAB-mediated and the Le(x)-dependent binding by knockout mutagenesis in one distinct strain, H. pylori P1. We show here that the mutagenesis of either alpA and/or alpB dramatically reduced the adherence of H. pylori P1 to a given gastric biopsy section. None of these mutations influenced the surface exposure of the Le(x) antigen, suggesting that the assembly and/or presentation of LPS is independent of the AlpAB outer membrane proteins. However, a truncation of the LPS O-side chain by a galE mutation abolished the presentation of the Le(x) epitope. This Le(x)-negative strain did not show any significant reduction in its binding capacity to the gastric tissue, when compared with the corresponding wild-type strain. From these data we conclude that the AlpAB-specific adherence is independent of the composition of the LPS and that the oligomeric Le(x) structure does not confer binding to the gastric biopsy material used in this study. As the adhesion properties of our H. pylori strain P1 vary in dependence on the respective biopsy donor it is assumed that the surface-exposed Le(x) epitope recognizes a different host cell receptor than AlpAB, which was probably not present in the tissue sections used in this study.     

Stereoselectivity of L-baclofen in hippocampal slices of the rat

Extra- and intracellular recording from hippocampal slices of the rat revealed the following effects when baclofen (BF) (0.1-10 microM) was added to the perfusion fluid: a block of synaptic potentials evoked by stimulation of stratum radiatum; a direct hyperpolarization and a conductance increase (for potassium ions) of CA1 pyramidal cells. All this activity was found in the L- none in the D-enantiomer. D-BF did not antagonize the action of L-BF.     

Comparison of the direct radiolabeled antiglobulin assay and the direct immunobead binding test for detection of sperm-associated antibodies

Thirty-seven semen samples were assayed for sperm-associated IgG and IgA using the immunobead test. Portions of these sperm samples were sent for testing with a direct radiolabeled antiglobulin assay and the testing results were compared. If the results of the immunobead test when only tail-tip bead binding was noted are regarded as negative, there was close correlation between the two assay methodologies.