Defense of zebrafish embryos against Streptococcus pneumoniae infection is dependent on the phagocytic activity of leukocytes

Severe community acquired pneumonia caused by Streptococcus pneumoniae is the most common cause of death from infection in developing countries. Serotype specific conjugate vaccines have decreased the incidence of invasive infections, but at the same time, disease due to non-vaccine serotypes have increased. New insights into host immune mechanisms against pneumococcus may provide better treatment and prevention strategies. Zebrafish is an attractive vertebrate model for studying host immune responses and infection biology. Here we show that an intravenous challenge with pneumococcus infects zebrafish embryos leading to death in a dose dependent manner. Survival rates correlate with the bacterial burden in the embryos. The production of proinflammatory cytokines is induced in zebrafish after pneumococcal exposure. Importantly, morpholino treated embryos lacking either myeloid cells or the ability to phagocytose bacteria have lowered survival rates compared to wild type embryos after pneumococcal challenge. These data suggest that the survival of zebrafish embryos upon intravenous infection with S. pneumoniae is dependent on the clearance of the bacteria by phagocytosing cells. Additionally, we demonstrate that mutant pneumococci lacking known virulence factors are attenuated in the zebrafish model. Our data demonstrate that zebrafish embryos can be used for study innate immune responses as well as virulence determinants in pneumococcal infections.     

Differences in protein fractions of avian plasma among three commercial electrophoresis systems

Previous studies have defined the presence of 6 protein fractions in plasma from many psittaciform species. Additionally, extensive reference intervals have been published for many of these species with the Beckman Paragon electrophoresis system, which had been commonly used in clinical laboratories to analyze the protein fractions of avian plasma. In mid-2009, Beckman discontinued the Paragon product line, leaving 2 primary alternative systems: Helena and Sebia. To compare electrophoresis results from the 3 commercial protein electrophoresis systems, specimens from 40 African grey parrots (Psittacus erithacus) were analyzed with the electrophoresis systems from Beckman, Helena, and Sebia. Marked differences in fraction migration were found between the Beckman/Helena and Sebia systems, which manifested as a large decrease in prealbumin and an increase in alpha1 globulins in the latter system. Both proportional and constant errors were observed among the fraction quantitation data of both the Helena and Sebia systems compared with the Beckman system. Based on Bland-Altman plot data and imprecision studies, the Helena system appears more similar with the Beckman system, although neither the Helena nor the Sebia systems are identical to the Beckman system. Because of the differences in electrophoresis methods, clinicians should be careful to consistently use particular clinical laboratories. For best application, reference intervals should be established based on both species and electrophoresis system.     

Synthesis and biological evaluation of novel 2,4-disubstituted-1,3-thiazoles as anti-Candida spp. agents

A new series of [4-(4′-substituted-phenyl)thiazol-2-yl]hydrazine derivatives were synthesized in good yield (86-99%) and characterized by elemental analysis, IR, ¹H NMR, and mass spectral studies. The compounds were assayed for their in vitro broad-spectrum antifungal activity, compared to clotrimazole and fluconazole, against 20 clinical isolates of pathogenic Candida spp., representing five different species. The results showed that the presence of heterocyclic or bicyclic rings on hydrazone moiety in position C2 of thiazole revealed a promising selective inhibitory activity especially against Candida albicans and Candida glabrata.     

Event-related potentials reflecting the frequency of unattended spoken words: a neuronal index of connection strength in lexical memory circuits?

How are words represented in the human brain and can these representations be qualitatively assessed with respect to their structure and properties? Recent research demonstrates that neurophysiological signatures of individual words can be measured when subjects do not focus their attention on speech input. These automatic activations, which take the form of negative deflections of event-related potentials, can appear surprisingly early (within ~200 ms) and are based on robust connections within neuronal memory circuits encoding individual words that ignite even when attentional resources are scarce. A new and critical prediction of this framework is that words with high frequency of occurrence have especially strong connections of their underlying memory circuits and should thus yield more negative ERPs compared with rarer words. We tested this prediction by presenting our subjects, in passive non-attend conditions, with acoustically matched high- and low-frequency words along with pseudo-words. Using factorial and correlation analyses, we found that already at ~120 ms after the spoken stimulus information was available, amplitude of brain responses was modulated by the words' lexical frequency. Topographic mapping and source analysis suggested that this early automatic frequency effect originates from the left inferior-frontal cortices. While, at this early latency, lexical differences between words and pseudo-words (more negative-going potential for meaningful words) could be seen only for the most frequent word stimuli, later-on (~270 ms), a more global lexicality effect with bilateral perisylvian sources was found for all stimuli, suggesting faster access to more frequent lexical entries. Our results support the account of word memory traces as interconnected neuronal circuits, and suggest that speed and magnitude of their activation are determined by their internal connection strength, which, in turn, is determined by the everyday language use.     

Biocompatibility of alloys used in orthodontics evaluated by cell culture tests

The cytotoxicity of the most common alloys used in orthodontic appliances was determined by cell culture testing. Human gingival fibroblasts were cultured on 304 and 316 stainless steel, on brazing alloy composed of palladium (Pd), copper (Cu), and silver (Ag), and on plastic substrate (control). Studies were carried out with SEM and radiolabeled precursor incorporation. Cells were cultured in MEM without serum but with the addition of (3)H-thymidine to evaluate cell proliferation and (3)H-glucosamine to evaluate glycosaminoglycan (GAG) synthesis and secretion in the culture medium. Moreover, gingival fibroblasts were cultured in the presence of some metal ions generally released by orthodontic appliances to evaluate the cytotoxic effects of single ions. Morphologic observations with SEM and radiolabeled incorporation studies showed that 304 and 316 stainless steel were more biocompatible than the brazing alloy. Among the metal ions tested, Ag and Pd, constituents of the brazing alloy, showed the highest cytotoxicity.