Ultra-structural identification of interstitial cells of Cajal in the zebrafish Danio rerio

The interstitial cells of Cajal (ICCs) are important mediators of gastrointestinal (GI) motility because of their role as pacemakers in the GI tract. In addition to their function, ICCs are also structurally distinct cells most easily identified by their ultra-structural features and expression of the tyrosine kinase receptor c-KIT. ICCs have been described in mammals, rodents, birds, reptiles, and amphibians, but there are no reports at the ultra-structural level of ICCs within the GI tract of an organism from the teleost lineage. We describe the presence of cells in the muscularis of the zebrafish intestine; these cells have similar features to ICCs in other vertebrates. The ICC-like cells are associated with the muscularis, are more electron-dense than surrounding smooth muscle cells, possess long cytoplasmic processes and mitochondria, and are situated opposing enteric nervous structures. In addition, immunofluorescent and immunoelectron-microscopic studies with antibodies targeting the zebrafish ortholog of a putative ICC marker, c-KIT (kita), showed c-kit immunoreactivity in zebrafish ICCs. Taken together, these data represent the first ultra-structural characterization of cells in the muscularis of the zebrafish Danio rerio and suggest that ICC differentiation in vertebrate evolution dates back to the teleost lineage.     

Specification of an anterior neuroectoderm patterning by Frizzled8a-mediated Wnt8b signalling during late gastrulation in zebrafish

Wnts have been shown to provide a posteriorizing signal that has to be repressed in the anterior neuroectoderm for normal anteroposterior (AP) patterning. We have previously identified a zebrafish frizzled8a (fz8a) gene expressed in the presumptive anterior neuroectoderm as well as prechordal plate at the late gastrula stage. We have investigated the role of Fz8a-mediated Wnt8b signalling in anterior brain patterning in zebrafish. We show that in zebrafish embryos: (1) Wnt signalling has at least two different stage-specific posteriorizing activities in the anterior neuroectoderm, one before mid-gastrulation and the other at late gastrulation; (2) Fz8a plays an important role in mediating anterior brain patterning; (3) Wnt8b and Fz8a can functionally interact to transmit posteriorizing signals that determine the fate of the posterior diencephalon and midbrain in late gastrula embryos; and (4) Wnt8b can suppress fz8a expression in the anterior neuroectoderm and potentially affect the level and/or range of Wnt signalling. In conclusion, we suggest that a gradient of Fz8a-mediated Wnt8b signalling may play crucial role in patterning the posterior diencephalon and midbrain regions in the late gastrula.     

Kinetics of charge separation and A0- --> A1 electron transfer in photosystem I reaction centers

The charge separation P700*A(0) --> P700(+)A(0)(-) and the subsequent electron transfer from the primary to secondary electron acceptor have been studied by subtracting absorption difference profiles for cyanobacterial photosystem I (PS I) complexes with open and closed reaction centers. Samples were excited at 660 nm, which lies toward the blue edge of the core antenna absorption spectrum. The resulting PS I kinetics were analyzed in terms of the relevant P700, P700(+), A(0), and A(0)(-) absorption spectra. In our kinetic model, the radical pair P700(+)A(0)(-) forms with 1.3 ps rise kinetics after creation of electronically excited P700*. The formation of A(1)(-) via electron transfer from A(0)(-) requires approximately 13 ps. The kinetics of the latter step are appreciably faster than previously estimated by other groups (20--50 ps).     

Some potential anticancer palladium(II) complexes of 2,2'-bipyridine and amino acids

Nine new palladium(II) complexes of the formula [Pd(bipy)(AA)]n+ (where bipy is 2,2'-bipyridine, AA is an anion of L-cysteine, L-aspartic acid, L-glutamic acid, L-methionine, L-histidine, L-arginine, L-phenylalanine, L-tyrosine, or L-tryptophan, and n = 0 or 1) have been synthesized by interaction of [Pd(bipy)Cl2] with an appropriate sodium salt of amino acid in water. These palladium(II) complexes have been characterized by chemical analysis and by visible, infrared, and 1H NMR spectroscopy. The modes of binding of amino acids in these palladium complexes have been ascertained by infrared and 1H NMR spectroscopy. The molar conductances of these complexes in water suggest that they are either nonelectrolytes or 1:1 electrolytes. These palladium complexes have shown growth inhibition against L1210 lymphoid leukemic, P388 lymphocytic leukemic, Sarcama 180, and Ehrlich ascites tumor cells. Some of these complexes show I.D.50 values comparable to or lower than cis-diamminedichloroplatinum(II).     

Development and validation of a rapid and sensitive assay for simultaneous quantification of midazolam, 1′-hydroxymidazolam,and 4-hydroxymidazolam by liquid chromatography coupled to tandem mass-spectrometry

Midazolam is an ultra short acting benzodiazepine derivative and a specific probe for phenotyping cytochrome P450 (P450) 3A4/5 activity. A rapid, sensitive, and selective LC–MS/MS method was developed for simultaneous quantitation of midazolam and its metabolites (1′-hydroxymidazolam and 4-hydroxymidazolam). Deuterated (D₅) analog of midazolam was utilized as an internal standard. Sample preparation either from human plasma (100 μL) or liver microsomal incubations involved a simple protein precipitation using acetonitrile (900 μL) with an average recovery of >90% for all compounds. The chromatographic separation was achieved using Zorbax-SB Phenyl, Rapid Resolution HT (2.1 mm × 100 mm, 3.5 μm) and a gradient elution with 10 mM ammonium acetate in 10% methanol (A) and acetonitrile (B). The flow rate was 0.25 mL/min and total run time was 5.5 min. Calibration curves were linear over the concentration range of 0.100–250 ng/mL. The lower limit of quantitation (LLOQ) was 0.1 ng/mL for all three analytes. The accuracy and precision, estimated at LLOQ and three concentration levels of quality control samples in six replicates, were within 85–115%. In conclusion, a robust, simple and highly sensitive analytical method was developed and validated for the analysis of midazolam and its metabolites. This method is suitable for characterizing the P450 3A4/5 activity in vitro or in human pharmacokinetic studies allowing administration of smaller doses of midazolam.     

Potential Benefits,Limitations and Target Product-Profiles of Odor-Baited Mosquito Traps for Malaria Control in Africa

Background

Traps baited with synthetic human odors have been proposed as suitable technologies for controlling malaria and other mosquito-borne diseases. We investigated the potential benefits of such traps for preventing malaria transmission in Africa and the essential characteristics that they should possess so as to be effective.

Methods and Principal Findings

An existing mathematical model was reformulated to distinguish availability of hosts for attack by mosquitoes from availability of blood per se. This adaptation allowed the effects of pseudo-hosts such as odor-baited mosquito traps, which do not yield blood but which can nonetheless be attacked by the mosquitoes, to be simulated considering communities consisting of users and non-users of insecticide-treated nets (ITNs), currently the primary malaria prevention method. We determined that malaria transmission declines as trap coverage (proportion of total availability of all hosts and pseudo hosts that traps constitute) increases. If the traps are more attractive than humans and are located in areas where mosquitoes are most abundant, 20–130 traps per 1000 people would be sufficient to match the impact of 50% community-wide ITN coverage. If such traps are used to complement ITNs, malaria transmission can be reduced by 99% or more in most scenarios representative of Africa. However, to match cost-effectiveness of ITNs, the traps delivery, operation and maintenance would have to cost a maximum of US$4.25 to 27.61 per unit per year.

Conclusions and Significance

Odor-baited mosquito traps might potentially be effective and affordable tools for malaria control in Africa, particularly if they are used to complement, rather than replace, existing methods. We recommend that developers should focus on super-attractive baits and cheaper traps to enhance cost-effectiveness, and that the most appropriate way to deploy such technologies is through vertical delivery mechanisms.     

Bayesian DNA copy number analysis

Background  

Some diseases, like tumors, can be related to chromosomal aberrations, leading to changes of DNA copy number. The copy number of an aberrant genome can be represented as a piecewise constant function, since it can exhibit regions of deletions or gains. Instead, in a healthy cell the copy number is two because we inherit one copy of each chromosome from each our parents.     

Improvement in Yield and Purity of a Recombinant Malaria Vaccine Candidate Based on the Receptor-Binding Domain of Plasmodium vivax Duffy Binding Protein by Codon Optimization

A recombinant blood-stage vaccine for Plasmodium vivax malaria based on the functional receptor-binding domain of PvDBP (PvRII) has been developed. A synthetic gene coding for PvRII was expressed in Escherichia coli using codon optimization. Expression level of recombinant PvRII was 10% of the total cellular proteins. Truncated PvRII products, seen when the native PvRII gene was expressed, were absent in case of synthetic gene.     

Syntheses and spectroscopic studies of potential antitumor copper(II) complexes with 5-phenylazo-3-methoxy salicylidene thiosemicarbazone and N4 substituted thiosemicarbazones

Five new copper(II) complexes of 5-phenylazo-3-methoxy salicylidene thiosemicarbazone and N4 substituted thiosemicarbazones have been synthesized. They have been characterized by chemical analyses, magnetic, conductance data, and by ultraviolet (UV)--visible, infrared, and electron spin resonance spectra. The complexes have the general formula CuL2, where HL is the ligand. One representative complex has been screened in vitro and in vivo against P388 lymphocytic leukemia cells sensitive and resistant to adriamycin (P388/S and P388/R). It has shown promising growth inhibition activity. We are reporting here for the first time the antineoplastic activity of this complex against experimental tumor systems.