Method for Analysis, and Distribution Profile, of Covalently-linked Ferritin-daunorubicin Conjugate in the Blood of Trypanosome-infected Mice

Daunorubicin is a highly potent trypanocide in-vitro but is inactive in-vivo. When daunorubicin is conjugated to bovine serum albumin or horse spleen ferritin using Schiffs base linkages, the complex is trypanocidal in-vitro and in-vivo. We have developed novel analytical methods, using HPLC with fluorimetric detection, for the quantitation of daunorubicin and doxorubicin in biological samples, either as unconjugated drug, or when covalently linked to macromolecules or particles. Ferritin-daunorubicin conjugate (25 mg kg−1) was administered intraperitoneally to mice infected with monomorphic Trypanosoma brucei rhodesiense; peak plasma levels occurred after 1·5 h, and were 5 times higher than those resulting from administration of an equivalent amount of unconjugated daunorubicin. Plasma levels then declined rapidly (t½ for 1–6 h period was 0·58 and 0·86 h respectively for conjugated and unconjugated daunorubicin). However, higher plasma levels were seen 24 h after treatment, suggesting the distribution profile of daunorubicin when conjugated to ferritin is multiphasic with resultant high levels of daunorubicin obtained for a prolonged time period.

Evidence for a spin-aligned neutron-proton paired phase from the level structure of (92)Pd

Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

Rheo-NMR studies of the behavior of a nematic liquid crystal in a low-shear-rate regime: the transition from director alignment to reorientation

Deuterium NMR spectroscopy has been used to study the director dynamics of the nematic liquid-crystal system cetyl trimethylammonium bromide/D2O under the action of applied viscous torques. Shear forces were applied using a custom-built Couette cell that was introduced into an NMR superconducting magnet, so that its rotational axis was parallel to the magnetic field direction, along which the liquid-crystal director originally aligned. Subsequently, the inner cylinder of the cell was rotated continuously at different rates using a stepper motor. The resulting time evolution and ultimate steady-state orientation of the director, governed by the competition between the applied viscous torque with elastic and magnetic terms, was measured via observed changes in the deuterium spectrum. Using a simple gearbox allowed unprecedented access to a low-shear-rate regime in which, above a threshold shear rate, the director of part of the sample was observed to reorient, while the remaining part still aligned with the magnetic field. Subsequent increases in the applied rotational rate were found to increase the relative proportion of the orienting fraction. Spatially resolved NMR spectra showed that the orienting and field-aligned fractions formed separated bands across the gap of the Couette cell, with director reorientation being initiated at the moving inner wall. The behavior was found to be consistent with the often ignored variation in velocity gradient manifest across the gap of a cylindrical cell, so that as the angular frequency of the inner cylinder was increased the radial location of the critical shear rate required for reorientation traversed the gap. Once the applied rotational rate was sufficient to reorient the director of the entire sample, the dependence of the exhibited steady-state orientation on the average applied shear rate was measured. These results could be fitted to an analytical solution of the force-balance equation, made tractable by the assumption that the elasticity term was of minor significance and could be ignored. Additionally, the use of a numerical solution of the full force-balance equation, which explicitly includes elasticity and secondary flow and additionally allows the time evolution of the director orientation to be calculated, was investigated.

Isospin symmetry of odd-odd mirror nuclei: identification of excited states in N=Z-2 48Mn

Excited states have been observed in the N=Z-2 odd-odd nucleus 48Mn for the first time. Through comparison with the structure of 48V, a first high-spin study of an odd-odd mirror pair has been achieved. Differences between the T=1 analogue states in this pair have been interpreted in terms of Coulomb effects, with the aid of shell-model calculations in the full pf valence space. Unlike other mirror pairs, the energy differences have been interpreted almost entirely as due to a monopole effect associated with smooth changes in radius (or deformation) as a function of angular momentum. In addition, the large energy shift between analogue negative-parity states is interpreted in terms of the electromagnetic spin-orbit interaction in nuclei.

Optimizing an aerial spray for mosquito control

The role of proper flight line positioning was demonstrated to be critical for maximizing product efficacy when spraying in crosswinds by small-droplet spray strategies. Characterization studies indicated clearly that aircraft height, small drop emission distribution, and the ambient winds combine to dilute the spray cloud before impacting surface targets. A 5-fold increase in mortality was achieved when we used optimization techniques to position the aircraft during a crosswind treatment test.

A constant flow valve for hand-compression hydraulic sprayers

A commercial inline constant flow valve for hand-compression hydraulic sprayers was tested to evaluate its capability to maintain constant pressure to the nozzle down to a preset cut-out pressure. The flow-control valve provided consistent flow rates when used with the H.D. Hudson X-Pert 9.5-liter hand-compression sprayers. This flow valve may have potential for use in vector control operations.

Influence of monocaprin on the permeability of a diacidic drug BTA-243 across Caco-2 cell monolayers and everted gut sacs

This study explores the potential of the monoglyceride monocaprin as an enhancer of the epithelial permeability of the beta(3)-adrenoceptor agonist BTA-243, as an approach to improving the bioavailability of this drug. The permeabilities of BTA-243 and mannitol (paracellular marker) in Caco-2 cell monolayer and everted gut sac models in aqueous buffer (pH 6.8) in the presence of 1.3 and 2.0 mM monocaprin were compared with control (monocaprin-free) solutions over a period of 1 h. The transepithelial electrical resistance (TEER) of the Caco-2 cell monolayers was measured at regular time intervals throughout the experiment and after a recovery period of 30 h. Toxicological damage to the biological models associated with exposure to monocaprin was assessed by scanning electron microscopy and by the measurement of lactate dehydrogenase (LDH) release from everted gut sacs. The permeability of BTA-243 in epithelial monolayers was enhanced in the presence of 1.3 and 2.0 mM monocaprin. Measurements of TEER and mannitol permeability showed partial recovery of barrier properties after a 30 h period following exposure to 1.3 mM monocaprin. No structural damage was evident in these monolayers. Enhancement of Caco-2 permeability to BTA-243 by 2.0 mM monocaprin was significantly greater than by 1.3 mM but was irreversible; monolayers failed to recover their barrier properties after 30 h and changes in their gross morphology were observed. The mucosal to serosal transfer of BTA-243 in everted gut sac was enhanced but to a lesser extent than in the Caco-2 model. LDH release from everted gut sacs exposed to monocaprin was significantly less than that after exposure to Triton X-100, a nonionic surfactant known to cause membrane disruption.

Operational note indoor low-volume spray trials: handheld equipment evaluation

Four handheld aerosol-mist generators and 1 thermal fog generator were evaluated initially for their ability to deliver low flow rates (< or = 5 ml/min) of resmethrin insecticide. Two generators, the London Fog Eliminator and Clarke Pl, were then selected from that group to conduct a treatment of a block of 16 residences (4 x 4 grid) vs. direct treatment of individual residences to determine the most efficacious method of treating a group of small dwellings or a village. Data are presented on droplet density, volume median diameter, and mortality of caged mosquitoes treated with the P1 and Eliminator in residences treated as a group; and mortality for caged Aedes aegypti L. in residences treated individually with the P1 at various flow control settings and spray-on times.

Quantification of Nitrosomonas oligotropha and Nitrospira spp. using competitive polymerase chain reaction in bench-scale wastewater treatment reactors operating at different solids retention times

The effect of solids retention time (SRT) on ammonia-and nitrite-oxidizing bacteria was measured by Nitrosomonas oligotropha-like ammonia monooxygenase A and Nitrospira 16S rDNA competitive polymerase chain reaction assays in a complete-mix, bench-scale, activated-sludge system. During steady-state operation, nitrification was complete in the 20- and 10-day SRT reactors, nearly complete in the 5-day SRT reactor, and incomplete in the 2-day SRT reactor (76% ammonia oxidation and 85% nitrite oxidation). Total microbes, measured by dot-blot hybridizations, ranged from 3 x 10(11) to 3 x 10(12) cells/L, and increased with increasing SRTs. The concentration of the ammonia-oxidizer N. oligotropha dropped 100-fold from the 20-day SRT (5 x 10(9) cells/L) to the 2-day SRT (< or = 4 x 10(7) cells/L). Thus, N. oligotropha became a much smaller fraction of the total biomass in the poorly performing 2-day SRT reactor. The concentration of Nitrospira cells also decreased (10-fold) as the SRT was reduced from 20 days to 2 days. However, the number of Nitrospira cells was always greater than the number of N. oligotropha cells measured in each reactor (10- to 60-fold). While Nitrospira comprised 1 to 2% of the biomass, N. oligotropha represented only 0.04 to 0.27% of the total population. This low percentage suggests that N. oligotropha was not a dominant ammonia oxidizer in the bench-scale systems.

Biosynthesis of the linkage region of glycosaminoglycans: cloning and activity of galactosyltransferase II, the sixth member of the beta 1,3-galactosyltransferase family (beta 3GalT6)

A family of five beta1,3-galactosyltransferases has been characterized that catalyze the formation of Galbeta1,3GlcNAcbeta and Galbeta1,3GalNAcbeta linkages present in glycoproteins and glycolipids (beta3GalT1, -2, -3, -4, and -5). We now report a new member of the family (beta3GalT6), involved in glycosaminoglycan biosynthesis. The human and mouse genes were located on chromosomes 1p36.3 and 4E2, respectively, and homologs are found in Drosophila melanogaster and Caenorhabditis elegans. Unlike other members of the family, beta3GalT6 showed a broad mRNA expression pattern by Northern blot analysis. Although a high degree of homology across several subdomains exists among other members of the beta3-galactosyltransferase family, recombinant enzyme did not utilize glucosamine- or galactosamine-containing acceptors. Instead, the enzyme transferred galactose from UDP-galactose to acceptors containing a terminal beta-linked galactose residue. This product, Galbeta1,3Galbeta is found in the linkage region of heparan sulfate and chondroitin sulfate (GlcAbeta1,3Galbeta1,3Galbeta1,4Xylbeta-O-Ser), indicating that beta3GalT6 is the so-called galactosyltransferase II involved in glycosaminoglycan biosynthesis. Its identity was confirmed in vivo by siRNA-mediated inhibition of glycosaminoglycan synthesis in HeLa S3 cells. Its localization in the medial Golgi indicates that this is the major site for assembly of the linkage region.

Measuring total soil carbon with laser-induced breakdown spectroscopy (LIBS)

Improving estimates of carbon inventories in soils is currently hindered by lack of a rapid analysis method for total soil carbon. A rapid, accurate, and precise method that could be used in the field would be a significant benefit to researchers investigating carbon cycling in soils and dynamics of soil carbon in global change processes. We tested a new analysis method for predicting total soil carbon using laser-induced breakdown spectroscopy (LIBS). We determined appropriate spectral signatures and calibrated the method using measurements from dry combustion of a Mollisol from a cultivated plot. From this calibration curve we predicted carbon concentrations in additional samples from the same soil and from an Alfisol collected in a semiarid woodland and compared these predictions with additional dry combustion measurements. Our initial tests suggest that the LIBS method rapidly and efficiently measures soil carbon with excellent detection limits (approximately 300 mg/kg), precision (4-5%), and accuracy (3-14%). Initial testing shows that LIBS measurements and dry combustion analyses are highly correlated (adjusted r2 = 0.96) for soils of distinct morphology, and that a sample can be analyzed by LIBS in less than one minute. The LIBS method is readily adaptable to a field-portable instrument, and this attribute--in combination with rapid and accurate sample analysis--suggests that this new method offers promise for improving measurement of total soil carbon. Additional testing of LIBS is required to understand the effects of soil properties such as texture, moisture content, and mineralogical composition (i.e., silicon content) on LIBS measurements.

Structure-based phylogeny of class IIa tRNA synthetases in relation to an unusual biochemistry

The available three-dimensional information for class II aminoacyl-tRNA synthetases has been used to generate sequence alignments that strictly adhere to the structural equivalencies between members of subclass IIa of these enzymes. The resulting alignments were used to study their phylogenetic relationships. In particular, the entire set of available sequences of prolyl-tRNA synthetases was analyzed in this way. In contrast to recent reports, we conclude that the evolutionary pattern of prolyl-tRNA synthetases does not obviously conform to the canonical phylogenetic distribution. The pattern found for these enzymes may be related to their biochemical characteristics. Our results indicate a potential relationship between the evolutionary pattern of prolyl-tRNA synthetases and the emergence of two enzymatically distinct forms of these proteins.

Genomic and phylogenetic perspectives on the evolution of prokaryotes

Prokaryotes have been at the forefront of the genome sequencing revolution. Many genomes have been completely sequenced, revealing much about bacterial and archaeal genome content and organization. Yet, a meaningful evolutionary picture of prokaryotes still eludes us. Much of the problem lies in understanding the mode and tempo of genome evolution. Here phenylalanyl-tRNA synthetase is used as an example of the complex interplay among lateral gene transfer, operon recombination, and gene recruitment in the evolution of some prokaryotic genes. Promising new approaches to genomic analyses, which could add to our understanding prokaryotic evolution and help in their classification, are discussed.

Enhanced 3-O-sulfation of galactose in Asn-linked glycans and Maackia amurensis lectin binding in a new Chinese hamster ovary cell line

We report the characterization of two Chinese hamster ovary cell lines that produce large amounts of sulfated N-linked oligosaccharides. Clones 26 and 489 were derived by stable transfection of the glycosaminoglycan-deficient cell mutant pgsA-745 with a cDNA library prepared from wild-type cells. Peptide:N-glycanase F released nearly all of the sulfate label, indicating that sulfation had occurred selectively on the Asn-linked glycans. Hydrazinolysis followed by nitrous acid treatment at pH 4 and borohydride reduction yielded reduced sulfated disaccharides that comigrated with standard Gal3SO4beta1-4anhydromannitol. The disaccharides were resistant to periodate oxidation but became sensitive after the sulfate group was removed by methanolysis, indicating that the sulfate was located at C3 of the galactose residues. Maackia amurensis lectin bound to the sulfated glycopeptides on the cell surface and in free form, even after sialidase treatment. This finding indicates that the lectin requires only a charged group at C3 of the galactose unit and not an intact sialic acid. Growth of cells with chlorate restored sialidase sensitivity to lectin binding, indicating that sulfation and sialylation occurred largely at the same sites. The enhanced sulfation was due to elevated sulfotransferase activity that catalyzed transfer of sulfate from phosphoadenosine-5'-phosphosulfate to Galbeta1-4(3)GlcNAcbeta-O-naphthalenemethanol.

Universal trees based on large combined protein sequence data sets

Universal trees of life based on small-subunit (SSU) ribosomal RNA (rRNA) support the separate mono/holophyly of the domains Archaea (archaebacteria), Bacteria (eubacteria) and Eucarya (eukaryotes) and the placement of extreme thermophiles at the base of the Bacteria. The concept of universal tree reconstruction recently has been upset by protein trees that show intermixing of species from different domains. Such tree topologies have been attributed to either extensive horizontal gene transfer or degradation of phylogenetic signals because of saturation for amino acid substitutions. Here we use large combined alignments of 23 orthologous proteins conserved across 45 species from all domains to construct highly robust universal trees. Although individual protein trees are variable in their support of domain integrity, trees based on combined protein data sets strongly support separate monophyletic domains. Within the Bacteria, we placed spirochaetes as the earliest derived bacterial group. However, elimination from the combined protein alignment of nine protein data sets, which were likely candidates for horizontal gene transfer, resulted in trees showing thermophiles as the earliest evolved bacterial lineage. Thus, combined protein universal trees are highly congruent with SSU rRNA trees in their strong support for the separate monophyly of domains as well as the early evolution of thermophilic Bacteria.

Lipid modification of prelipoproteins is dispensable for growth in vitro but essential for virulence in Streptococcus pneumoniae

A Deltalgt (Lgt, lipoprotein diacylglyceryl transferase) isogenic mutant was obtained which indicates that lgt is not essential for cell growth in vitro, like in the Gram-positive bacterium Bacillus subtilis, but unlike in the proteobacteria Escherichia coli and Salmonella typhimurium. The mutation was transduced to a virulent strain. A 5 log attenuation was observed in a respiratory tract model of infection. Metabolic labeling by [U-14C]palmitate revealed the presence of eight to ten lipoproteins in the wild-type strain only, with molecular masses between 15 and 80 kDa. Our findings suggest a major difference in the role of lipoproteins in Gram-positive bacteria versus the proteobacteria.

Phylogenetic analyses do not support horizontal gene transfers from bacteria to vertebrates

Horizontal gene transfer (HGT) has long been recognized as a principal force in the evolution of genomes. Genome sequences of Archaea and Bacteria have revealed the existence of genes whose similarity to loci in distantly related organisms is explained most parsimoniously by HGT events. In most multicellular organisms, such genetic fixation can occur only in the germ line. Therefore, it is notable that the publication of the human genome reports 113 incidents of direct HGT between bacteria and vertebrates, without any apparent occurrence in evolutionary intermediates, that is, non-vertebrate eukaryotes. Phylogenetic analysis arguably provides the most objective approach for determining the occurrence and directionality of HGT. Here we report a phylogenetic analysis of 28 proposed HGT genes, whose presence in the human genome had been confirmed by polymerase chain reaction (PCR). The results indicate that most putative HGT genes are present in more anciently derived eukaryotes (many such sequences available in non-vertebrate EST databases) and can be explained in terms of descent through common ancestry. They are, therefore, unlikely to be examples of direct HGT from bacteria to vertebrates.

The effect of unfractionated vs. low molecular weight heparin on tissue factor pathway inhibitor levels in hospital inpatients

Although heparin is widely used as an antithrombotic agent, its multiple mechanisms of action are not fully defined. Recent work has suggested that tissue factor pathway inhibitor (TFPI) may contribute to the antithrombotic activity of heparin by inhibiting the extrinsic pathway of coagulation. We have investigated the effect of heparin on TFPI and have found that when unfractionated heparin is given by continuous intravenous infusion to hospitalized inpatients, TFPI levels increase 2.3-fold and remain high as long as heparin is continued, but return to baseline levels soon after the infusion is stopped. In contrast, therapeutic doses of the low molecular weight heparin, dalteparin, resulted in significantly less TFPI induction. Given the increasing number of studies establishing the clinical efficacy of low molecular weight heparins as antithrombotic agents, these results suggest that TFPI may not be a major contributor to the antithrombotic effect of heparin.

Identification, cloning, and expression of a functional phenylalanyl-tRNA synthetase (pheRS) from Staphylococcus aureus

Phenylalanyl-tRNA synthetase (pheRS) is unique among aminoacyl tRNA synthetases in that it is a heterotetrameric enzyme composed of two alpha-subunits and two larger beta-subunits. In prokaryotes, the alpha- and beta-subunits of pheRS are encoded by the genes pheS and pheT, respectively. In this report we describe the isolation of a DNA fragment (3.52 kb) containing the pheS and pheT genes from a Staphylococcus aureus (WCUH29) genomic DNA library. Both genes, found as a part of transcriptional operon, were predicted to encode polypeptides which showed strong primary and structural similarity to prokaryotic phenylalanyl-tRNA synthetase alpha- and beta- subunits. We describe the high-level overexpression and purification of recombinant S. aureus pheRS using pheS and pheT genes as part of an artificial operon in Escherichia coli. For comparative analysis we also report a procedure for the purification of native pheRS from S. aureus (Oxford Strain) and demonstrate that Michaelis-Menten parameters for both recombinant and native enzyme, at least for phenylalanine tRNA aminoacylation are comparable.