A horizontally polarizing liquid trap enhances the tabanid-capturing efficiency of the classic canopy trap.

Host-seeking female tabanid flies, that need mammalian blood for the development of their eggs, can be captured by the classic canopy trap with an elevated shiny black sphere as a luring visual target. The design of more efficient tabanid traps is important for stock-breeders to control tabanids, since these blood-sucking insects can cause severe problems for livestock, especially for horse- and cattle-keepers: reduced meat/milk production in cattle farms, horses cannot be ridden, decreased quality of hides due to biting scars. We show here that male and female tabanids can be caught by a novel, weather-proof liquid-filled black tray laid on the ground, because the strongly and horizontally polarized light reflected from the black liquid surface attracts water-seeking polarotactic tabanids. We performed field experiments to reveal the ideal elevation of the liquid trap and to compare the tabanid-capturing efficiency of three different traps: (1) the classic canopy trap, (2) the new polarization liquid trap, and (3) the combination of the two traps. In field tests, we showed that the combined trap captures 2.4-8.2 times more tabanids than the canopy trap alone. The reason for the larger efficiency of the combined trap is that it captures simultaneously the host-seeking female and the water-seeking male and female tabanids. We suggest supplementing the traditional canopy trap with the new liquid trap in order to enhance the tabanid-capturing efficiency.

2,3-Diphosphoglycerate phosphatase/synthase: a potential target for elevating the diphosphoglycerate level in human red blood cells.

To exploit the well documented effect of 2,3-diphosphoglyceric acid (2,3-DPG) in enhancing oxygen delivery by human erythrocytes, we have investigated whether the DPG synthase/phosphatase enzyme system can be targeted to increase DPG levels in the cell. The hydrolytic activity (phosphatase) of the DPG metabolizing enzyme complex exhibits a marked dependence on a physiological effector, 2-phosphoglycolate. Little phosphatase activity is detected in the absence of this activator irrespective of the concentrations of the substrate. The phosphoglycolate-dependent phosphatase activity is competitively inhibited by a glycolytic intermediate, 3-phosphoglyceric acid (3-PGA). The 3-PGA inhibition persists when the 2,3-DPG concentration is raised to saturation level. In contrast, 3-PGA enhances the DPG synthase activity in a dose-dependent manner. In intact red cells, one-half of the cellular DPG content is depleted after 6 hr at 37 degrees C in glucose-free medium. The rate of 2,3-DPG degradation is accelerated when the cellular level of phosphoglycolate is increased by incubation with exogenous glycolate. Together, these results indicate that 2,3-DPG content in erythrocytes can be directly regulated through modulation of phosphatase/synthase activities. In support of this notion, a pyruvate kinase inhibitor, L-alanine, increases by 2-fold the cellular 3-PGA level. This is accompanied by a significant increase (30%) in 2,3-DPG content in human red blood cells. It is postulated that the DPG-promoting action of 3-PGA is mediated through simultaneous phosphatase inhibition and synthase activation. Furthermore, as a result of increased DPG accumulation, the oxygen-hemoglobin dissociation curve in L-alanine-treated cells is rightward shifted by 2.5 torr.

An LTC4 binding site in gastric mucosa is shared with glutathione.

Recent results from our laboratory and others have suggested a possible physiological functional role(s) for leukotrienes in gastric mucosa. In the present study 3H-LTC4 binds to washed rabbit gastric mucosal membranes at 4 degrees C with a Kd of 5 nM and a Bmax of 31.3 pmol/mg protein. Leukotrienes D4, E4, B4, oxidized glutathione (GSSG), cysteine, and mercaptoethanol were unable to displace 3H-LTC4 at 1 microM concentrations, while GSH inhibited binding with a Ki of 47 nM. Differential centrifugation of the membrane preparation to remove mitochondria resulted in Ki values for LTC4 and GSH of 14 and 23 nM, respectively. The similar binding affinities and competitive receptor binding kinetics for GSH and LTC4, the low affinity for other leukotrienes, and a Ki of 7 microM for hematin, a substrate for glutathione S-transferase, suggest that 3H-LTC4 binds to a GSH site which does not discriminate between LTC4 and GSH. Membranes fractionated to remove mitochondria were assayed for glutathione peroxidase, gamma-glutamyltranspeptidase, and glutathione S-transferase as possible binding sites for LTC4. We were unable to detect enzyme activity for any of the three enzymes. The binding of LTC4 in gastric mucosa differs from other tissues with respect to the high affinity for GSH, and thus becomes an appropriate tissue in which to investigate the relationships between LTC4 and GSH.

Photosynthetic energy conservation investigated by thermoluminescence. Activation energies and half-lives of thermoluminescence bands of chloroplasts determined by mathematical resolution of glow curves.

Thermoluminescence of isolated chloroplasts was analysed by a computer-assisted multicomponent curve fitting procedure to determine the activation energies, the free energies of activation, frequency factors and half-lives of the component bands of the glow curve. Optimal fit was obtained in the temperature region from -80 degrees C to +80 degrees C by the resolution of the glow curve into seven bands with peak positions at -24, -12, +12, +17, +28, +44, and +69 degrees C. All of the activation free energies of the thermoluminescence bands were much higher than 0.59 eV, the minimum free energy of activation required for the back reaction of the primary charge separation as calculated on the basis of the theory of Ross and Calvin (Ross, R.T. and Calvin, M. (1967) Biophys. J. 7, 595-614). The high free energies of activation and long half-lives (longer than 50 ms) of the thermoluminescence bands suggest that thermoluminescence in the temperature region from -80 degrees C to 80+ C does not reflect the change recombination of primary products but represent the reversal of subsequent stabilization steps of the charge separation process which proceed along the acceptor and donor sides of Photosystem II.

Dichlorophenylurea-resistant oxygen evolution in Chlorella after cerulenin treatment.

Fluorescence spectra at 77 K, oxygen evolution at 30 degrees C and delayed fluorescence at 25 degrees C were measured in Chlorella pyrenoidosa cultures with and without cerulenin and subsequent 3-(3,4-dichlorophenyl)-1,1-dimethyl-urea (DCMU) treatment, respectively. In pure algal cultures the oxygen evolution was inhibited by DCMU and the long-time component of fluorescence was highly influenced by DCMU, as expected. In contrast, both oxygen evolution and delayed fluorescence became DCMU-resistant in cerulenin-treated cultures. The DCMU-resistance is correlated with a change in the fatty acid distribution of the thylakoid membrane, which also leads to changes in the prompt fluorescence. Cerulenin appears to be a promising new tool of diagnostics for the hitherto unsatisfactorily understood processes of oxygen evolution in photosynthesizing organisms.

Pharmacokinetics and disposition of lidamidine hydrochloride (WHR-1142A), a novel antidiarrheal agent, in rat and monkey.

14C-Labelled 1-(2,6-dimethylphenyl)-3-methylamidinourea hydrochloride (14C-WHR-1142A, lidamidine hydrochloride) was rapidly and quantitatively absorbed from the gastrointestinal tract of rat and monkey after a single oral dose of 5 mg/kg (base). Peak 14C levels occurred within 30 min and the radiolabel was found in both the plasma and cellular components of whole blood. The half-life of the parent compound was 30 min in rat and 1 h in the monkey. The label was essentially cleared from all tissues examined within 24 h in the rat. In both rat and monkey, the compound was extensively metabolized (greater than 90%) prior to excretion and eliminated primarily in the urine (95% of the 14C dose could be accounted for in urine within 24 h in the monkey and 65% within 24 h in the rat); about 15-20% of the dose was recovered in feces within 24 h in the rat. In rat, a significant portion of the dose was eliminated in bile, and enterohepatic recirculation of 14C excreted in bile occurred. In contrast, biliary elimination of 14C was not a major pathway in the monkey.

Quantitative determination of fenclorac in serum.

A spectrophotometric method for the analysis of fenclorac and its metabolite, 3-chloro-4-cyclohexylbenzeneglycolic acid, in human serum was developed. The parent compound represented at least 90% of the total species present in blood; the metabolite was present to the extent of about 10%, primarily in the elimination phase. The basic procedure consists of extraction of both compounds from serum, further extraction to remove interfering substances, alkaline conversion of fenclorac to the alpha-hydroxy acid metabolite, oxidation of this metabolite to the corresponding benzaldehyde derivative, and spectrophotometric measurement of the absorbance of the aldehyde at 252 nm. A comparison of serum concentrations obtained by this method with concentrations calculated from 14C-data following oral administration of 1-14C-fenclorac to eight normal adult volunteers indicated a 90% correlation between methodologies over a range of 1.4-25.5 microgram of fenclorac/ml of serum.

Correlation of in vitro and in vivo methodology for evaluation of antacids.

The rate and extent of acid consumption of an antacid suspension and tablet were evaluated by in vitro and in vivo techniques. Four different test procedures were used to estimate in vitro antacid reactivity. In vivo effects were determined in the fasted and postcibal states in normal human subjects by a radiotelemetry procedure. The duration of elevation of intragastric pH greater than 3 was in agreement with in vitro estimates of total acid consumption of the antacid. There was also good correlation between onset, extent, and duration of in vivo antacid activity and a modified in vitro Beekman antacid test procedure. There was no significant difference in antacid activity of the tablet or suspension in either in vitro or in vivo test procedures. A wide variation in antacid activity was observed between subjects and also in the fasted versus postcibal states. These studies emphasize the requirements for standardization of antacid products by comparactive in vitro and in vivo evaluations to facilitate individualized dose titration of the antacid in each patient and correlation of the acid secretion rate in various types of GI disease with the antacid dose.

Induction of hepatic enzymes by methaqualone and effect on warfarin-induced hypoprothrombinemia.

The effect of methaqualone on the induction of hepatic enzymes was evaluated in rats and compared with that of phenobarbital by measuring effects on hexobarbital and methaqualone hypnosis, plasma and tissue levels of methaqualone, hepatic aniline hydroxylase and aminopyrine demethylase activity and warfarin-induced hypoprothrombinemia. Maximal reductions in hexobarbital hypnosis occurred 3 days after daily administration of 60 mg of methaqualone per kg per day. At this time, the activities of aniline hydroxylase and aminopyrine demethylase were increased 60 and 139%, respectively, and hepatic microsomal proteins increased 15% above controls in methaqualone-pretreated animals. Methaqualone altered its own metabolism as demonstrated by a 48% reduction in methaqualone hypnosis in pretreated animals. The extent and duration of induction by phenobarbital was considerably greater than methaqualone in all experiments. Methaqualone pretreatment did not affect warfarin-induced hypoprothrombinemia, whereas phenobarbital-pretreated animals showed a 32 to 64% reduction in response to the anticoagulant. These studies indicate that methaqualone is a relatively weak inducer of hepatic drug-metabolizing enzymes and has no effect on the anticoagulant acitivty of warfarin.