Heterogeneity of chromosomal genes encoding chloramphenicol resistance in streptococci

The DNA of 21 chloramphenicol-resistant plasmid-free streptococci was tested for sequence homology with the genes encoding chloramphenicol acetyltransferase (cat) of the staphylococcal plasmids pC194 and pC221. Homology to the cat gene of pC194 was detected in 11 strains, including the 8 strains of Streptococcus pneumoniae examined, and homology to cat of pC221 was found in 3 strains. The DNA of 7 strains did not detectably hybridize with either probe.     

Lauryl gallate inhibits the activity of protein tyrosine kinase c-Src purified from human platelets

The inhibitory effect of gallic acid (3,4,5-trihydroxybenzoic acid), and its ester derivatives methyl, propyl, octyl and lauryl has been tested on the tyrosine kinase activity of affinity purified c-Src from human platelets, using the artificial substrate Poly (Glu,Na,Tyr) 4:1. When tested as inhibitor of the autophosphorylation of the enzyme and the phosphorylation of the protein tyrosine phosphatase SHP-1 by c-Src, lauryl gallate was found to be a more potent inhibitor than other widely used protein tyrosine kinase (PTK) inhibitors such as genistein and herbimycin A. However, lauryl gallate did not inhibit the activity of the serine threonine kinases protein kinase A (PKA) and casein kinase II (CKII) from rat brain.     

Mechanistic aspects of the induction of apoptosis by lauryl gallate in the murine B-cell lymphoma line Wehi 231

The effect of lauryl gallate (antioxidant E-312) has been studied on the mouse B-cell lymphoma line Wehi 231. This compound is able to inhibit protein tyrosine kinases (PTKs) in whole cells and in crude extracts with a better efficiency than other well-known PTK inhibitors such as herbimycin or genistein. Initial events triggered upon the incubation of cells with lauryl gallate in phosphate-buffered saline (up to 1 h) include the inhibition of tyrosine phosphorylation, discharge of the mitochondrial transmembrane potential, and induction of mRNA for Bcl-2. Long-term cultures in complete medium supplemented with fetal calf serum (up to 24 h) in the presence of this compound exhibit clear apoptotic features such as increase in phosphatidylserine in the cell surface, decrease in the functionality of mitochondria, cytochrome c release to the cytosol, activation of caspases, hypodiploidy, and oligonucleosomal breakdown of DNA. Comparison between Wehi cells overexpressing Bcl-2 (Wehi-bcl-2) with Wehi-neo cells shows a delay in the manifestations of the apoptotic signs, indicating that Bcl-2 has a partial protective effect on the apoptosis induced by lauryl gallate. The proapoptotic effect of lauryl gallate is not dependent on DNA or protein synthesis, is not blocked by the chelation of calcium, and is not reverted by N-acetylcysteine.     

Electrophysiological Correlates of Amnestic Mild Cognitive Impairment in a Simon Task

Amnestic mild cognitive impairment (aMCI) represents a prodromal stage of Alzheimer`s disease (AD), especially when additional cognitive domains are affected (Petersen et al., 2009). Thus, single-domain amnestic MCI (sdaMCI) and multiple-domain-amnestic MCI (mdaMCI) biomarkers are important for enabling early interventions to help slow down progression of the disease. Recording event-related potentials (ERPs) is a non-invasive and inexpensive measure of brain activity associated with cognitive processes, and it is of interest from a clinical point of view. The ERP technique may also be useful for obtaining early sdaMCI and mdaMCI biomarkers because ERPs are sensitive to impairment in processes that are not manifested at behavioral or clinical levels. In the present study, EEG activity was recorded in 25 healthy participants and 30 amnestic MCI patients (17 sdaMCI and 13 mdaMCI) while they performed a Simon task. The ERPs associated with visuospatial (N2 posterior-contralateral – N2pc -) and motor (lateralized readiness potential – LRP –) processes were examined. The N2pc amplitude was smaller in participants with mdaMCI than in healthy participants, which indicated a decline in the correlates of allocation of attentional resources to the target stimulus. In addition, N2pc amplitude proved to be a moderately good biomarker of mdaMCI subtype (0.77 sensitivity, 0.76 specificity). However, the LRP amplitude was smaller in the two MCI groups (sdaMCI and mdaMCI) than in healthy participants, revealing a reduction in the motor resources available to execute the response in sdaMCI and mdaMCI patients. Furthermore, the LRP amplitude proved to be a valid biomarker (0.80 sensitivity, 0.92 specificity) of both amnestic MCI subtypes.     

Lauryl Gallate Inhibits the Activity of Protein Tyrosine Kinase c-Src Purified from Human Platelets

The inhibitory effect of gallic acid (3,4,5-trihydroxybenzoic acid), and its ester derivatives methyl, propyl, octyl and lauryl has been tested on the tyrosine kinase activity of affinity purified c-Src from human platelets, using the artificial substrate Poly (Glu.Na, Tyr) 4:1. When tested as inhibitor of the autophosphorylation of the enzyme and the phosphorylation of the protein tyrosine phosphatase SHP-1 by c-Src, lauryl gallate was found to be a more potent inhibitor than other widely used protein tyrosine kinase (PTK) inhibitors such as genistein and herbimycin A. However, lauryl gallate did not inhibit the activity of the serine threonine kinases protein kinase A (PKA) and casein kinase II (CKII) from rat brain.