Colorimetric device for measurement of transvascular fluid flux in blood-perfused organs

The aim of this study was to develop a device capable of measuring transvascular fluid flux in blood-perfused organs. For any given blood flow through the organ (QT), transvascular flux (QF) can be considered as the fraction of QT exchange. Presumably, QF would change the background concentration of an impermeable tracer residing in the perfusate. Thus QF could be calculated from the relative changes in tracer concentration for any given QT. We have used Blue Dextran (1 g/l of blood) as the reference tracer. Because the minimum molecular weight of Blue Dextran is 2 X 10(6), we anticipated it to behave as an impermeable tracer in most organs. QF was simulated with continuous infusions of plasma, normal saline solution, and a 50% mixture of both. Changes in Blue Dextran concentration were continuously followed colorimetrically by changes in transmission of specific light at a wavelength of 632 nm. Because 632-nm light is affected by hematocrit and O2 saturation changes, two additional wavelengths were used: 815-nm, which is not affected by saturation or Blue Dextran concentration changes, was used to account for changes in hematocrit, and 887-nm specific light, which is not affected by Blue Dextran, served to correct for saturation changes. Red cells could not be used as the reference tracer because of the possibility of hematocrit changes independent of fluid flux (Fahraeus effect). The device so constructed proved capable of measuring rates of fluid infusion in the order of 0.1% of QT with a variability of 10% around the mean.     

Interaction of O,O,S-trimethyl phosphorothioate and O,S,S-trimethyl phosphorodithioate, the impurities of malathion with supercoiled PM2 DNA

The interaction of O,O,S-trimethyl phosphorothioate and O,S,S-trimethyl phosphorodithioate, the impurities found in malathion, with DNA at pH 8.0, was investigated. Supercoiled PM2 DNA was incubated with these compounds at pH 8.0 at 37 degrees C and then the superhelicity of the modified DNA was determined by gel electrophoresis. Both compounds caused unwinding of supercoiled DNA in dose- and incubation time-dependent manner. O,S,S-trimethyl phosphorodithioate was a more potent agent than O,O,S-trimethyl phosphorothioate. At 37 degrees C following 2.0 hours incubation, 100 mM O,S,S-trimethyl phosphorodithioate produced fully unwound DNA, whereas at 200 mM O,O,S-trimethyl phosphorothioate produced 80% unwound DNA following 12 hours' incubation. At the same condition, 5 mM methyl methanesulfonate, a potent alkylating mutagen, produced fully unwound DNA following 1 hour incubation at 5 mM. These results indicated that there were chemical interactions between these agents and DNA. The possibility of the interaction of OOS-TMP being as a covalent intercalation as well as strand nicking was discussed.     

Comparison of the interaction of antineoplastic aminoanthraquinone analogs with DNA using competitive fluorescence polarization

1,4-dihydroxy-5, 8-bis{{2-{(2-hydroxyethyl)amino}ethyl}amino} -9,10-anthracenedione (NSC 287836) and 1,4-bis{{2-{(2-hydroxyethyl) amino}ethyl}amino}-9, 10-anthracenedione diacetate (NSC 287513) have shown activity against solid tumors and are now in Phase I clinical trials. Fluorescence polarization was used to determine the extent of inhibition of the binding of acridine orange to DNA (Richardson, Roboz, Holland, Res. Comm. Chem. Pathol. Pharmac. $\text{27}$, 497, 1980). Displacement of 50% of acridine orange from calf thymus DNA was obtained with 0.18 uM of NSC 287836 while 0.52 uM of NSC 287513 was needed to displace an equivalent amount of acridine orange. NSC 287513 showed preference for polynucleotides of high adenine+thymine content while NSC 287836 did not. Analogs lacking both hydroxyethylaminoethyl-amino side chains did not displace acridine orange.     

Organic anions facilitate the mobilization of soil organic phosphorus and its subsequent lability to phosphatases

Plant and Soil - Organic anions commonly released from plant roots and microorganisms are widely reported to mobilize soil phosphorus (P). We characterized soil organic P that was mobilized by...     

Interplay between age‐based competitive asymmetries within the brood and direct competition between inbred and outbred offspring in a burying beetle

Theory suggests that intraspecific competition associated with direct competition between inbred and outbred individuals should be an important determinant of the severity of inbreeding depression. The reason is that, if outbred individuals are stronger competitors than inbred ones, direct competition should have a disproportionate effect on the fitness of inbred individuals. However, an individual's competitive ability is not only determined by its inbreeding status but also by competitive asymmetries that are independent of an individual's inbreeding status. When this is the case, such competitive asymmetries may shape the outcome of direct competition between inbred and outbred individuals. Here, we investigate the interface between age‐based competitive asymmetries within broods and direct competition between inbred and outbred offspring in the burying beetle Nicrophorus vespilloides. We found that inbred offspring had lower survival than outbred ones confirming that there was inbreeding depression. Furthermore, seniors (older larvae) grew to a larger size and had higher survival than juniors (younger larvae), confirming that there were age‐based competitive asymmetries. Nevertheless, there was no evidence that direct competition between inbred and outbred larvae exacerbated inbreeding depression, no evidence that inbreeding depression was more severe in juniors and no evidence that inbred juniors suffered disproportionately due to competition from outbred seniors. Our results suggest that direct competition between inbred and outbred individuals does not necessarily exacerbate inbreeding depression and that inbred individuals are not always more sensitive to poor and stressful conditions than outbred ones.     

Modeling the Tertiary Structure of the Patatin Domain of Neuropathy Target Esterase

Neuropathy target esterase (NTE) is a transmembrane protein of unknown function whose specific chemical modification by certain organophosphorus (OP) compounds leads to distal axonopathy. Therefore, solving the 3D structure of NTE would advance the understanding of its pathogenic and physiologic roles. In this study, the tertiary structures of the patatin (catalytic) domain and the N-terminal transmembrane domain of NTE were modeled using the crystal structures of patatin (PDB ID 1oxw) and moricin (PDB ID 1kv4) as templates. Sequence alignments and secondary structure predictions were obtained from the INUB server (Buffalo, NY). O and PyMol were used to build the PNTE and NTE TMD chains from these sequence alignments. The PNTE model was refined in the presence of water using the crystallography and NMR system, while the NTE TMD model was refined in vacuo using the GROMOS implementation in the Swiss PDB viewer. The modeled active site of NTE was found to consist of a Ser966-Asp1086 catalytic dyad, which is characteristic of phospholipase A2 enzymes. The Ser966 Ogamma was located 2.93 A from the Odelta2 of Asp1086. In addition, our NTE model was found to contain a single N-terminal transmembrane domain. This modeling effort provided structural and mechanistic predictions about the catalytic domain of NTE that are being verified via experimental techniques.