Liposome supported peritoneal dialysis in rat amitriptyline exposure with and without intravenous lipid emulsion

Liposome supported peritoneal dialysis is a recently described technique which may eventually be applicable in the clinical scenario of the intoxicated patient. We evaluated the hypothesis that intravenous injection of lipid emulsion (ILE) would augment acidic pH gradient liposome supported peritoneal dialysis (LSPD). Orogastrically amitriptyline dosed rats were treated with either Sodium bicarbonate (NaHCO3) intravenously and standard intraperitoneal dialysate (Group A); NaHCO3 intravenously and LSPD (Group B); or ILE and LSPD (Group C). The primary endpoint was dialysate amitriptyline concentration after a 60?min dwell. Secondary analysis included an estimate of extraction ratio for peritoneal blood flow (ERs). There were significantly higher intraperitoneal concentrations of amitriptyline and ERs in the two groups treated with LSPD (Group B, p?=?0.02, Group C, p?<?0.01 vs. Group A). There was no observed effect for ILE on intraperitoneal amitriptyline concentration or ERs (p?>?0.20). LSPD increased the amitriptyline concentration in peritoneal dialysate. No further increase was demonstrated with ILE. This may be either because such an effect is absent, or type II error. Exploratory analysis suggests LSPD may be driven by total rather than free drug concentrations.     

Low-dose pramlintide reduced food intake and meal duration in healthy, normal-weight subjects

Objective: We previously reported that a single preprandial injection (120 μg) of pramlintide, an analog of the β‐cell hormone amylin, reduced ad libitum food intake in obese subjects. To further characterize the meal‐related effects of amylin signaling in humans, we studied a lower pramlintide dose (30 μg) in normal‐weight subjects. Research Methods and Procedures: In a randomized, double‐blind, placebo‐controlled, cross‐over study, 15 healthy men (age, 24 ± 7 years; BMI, 22.2 ± 1.8 kg/m²) underwent a standardized buffet meal test on two occasions. After an overnight fast, subjects received a single subcutaneous injection of pramlintide (30 μg) or placebo, followed immediately by a standardized pre‐load meal. After 1 hour, subjects were offered an ad libitum buffet meal, and total caloric intake and meal duration were measured. Results: Compared with placebo, pramlintide reduced total caloric intake (1411 ± 94 vs. 1190 ± 117 kcal; Δ, ?221 ± 101 kcal; ?14 ± 9%; p = 0.05) and meal duration (36 ± 2 vs. 31 ± 3 minutes; Δ, ?5.1 ± 1.4 minutes; p < 0.005). Visual analog scale profiles of hunger trended lower and fullness higher during the first hour after pramlintide administration. In response to the buffet, hunger and fullness changed to a similar degree after pramlintide and placebo, despite subjects on pramlintide consuming 14% fewer kilocalories. Visual analog scale nausea ratings remained near baseline, without differences between treatments. Plasma peptide YY, cholecystokinin, and ghrelin concentrations did not differ with treatment, whereas glucagon‐like peptide‐1 concentrations after meals were lower in response to pramlintide than to placebo. Discussion: These observations add support to the concept that amylin agonism may have a role in human appetite control.     

Effects of GF-120 fruit fly bait concentrations on attraction, feeding, mortality, and control of Rhagoletis indifferens (Diptera: Tephritidae)

Effects of different concentrations of GF-120 NF Naturalyte Fruit Fly Bait on attraction and feeding responses, mortality, and control of the western cherry fruit fly, Rhagoletis indifferens Curran, were determined. In the laboratory, flies that had been exposed to sugar and yeast extract and then deprived of all food for 16-20 h were attracted to 40.0% GF-120, but not to 0.6 and 4.8% GF-120 (vol:vol). Nonstarved flies were not attracted to any concentration. Flies in the field were not attracted to 55.6% GF-120 on cherry leaves, and few flies fed on the bait. In the laboratory, males fed for shorter durations on and ingested lower amounts of 0.6% than 4.8 or 40.0% GF-120, but females fed equally on all concentrations. Spinosad in GF-120 was highly toxic to flies. Lethal concentrations50 (LC50 values) of spinosad for starved flies at 1-4 d were 1.5-0.7 ppm. When gravid flies were exposed to cherries treated with 0.6, 4.8, and 40.0% GF-120, mortality was greater at each higher concentration, but none prevented oviposition. Field spray tests comparing 0.6, 4.8, and 40.0% GF-120 in 225 ml of spray per cherry tree resulted in 79-94% lower larval infestations than in controls, but no differences were seen among the concentrations. Evidence from this study indicates that fresh 40.0% GF-120 was attractive in the laboratory but that flies were not attracted to fresh GF-120 from far distances within trees, suggesting that suppression of populations is caused in large part by flies finding the bait through normal movement over large areas.     

Regulation of Expression of Nitrate and Dinitrogen Assimilation by Anabaena Species

Anabaena sp. strain 7120 appeared more responsive to nitrogen control than A. cylindrica. Growth in the presence of nitrate strongly repressed the differentiation of heterocysts and fixation of dinitrogen in Anabaena sp. strain 7120, but only weakly in A. cylindrica. Nitrate assimilation by ammonium-grown cultures was strongly repressed in Anabaena sp. strain 7120, but less so in A. cylindrica. The repressive effect of nitrate on dinitrogen assimilation in Anabaena sp. strain 7120, compared to A. cylindrica, did not correlate with a greater rate of nitrate transport, reduction to ammonium, assimilation into amino acids, or growth. Although both species grew at similar rates with dinitrogen, A. cylindrica grew faster with nitrate, incorporated more ¹³NO₃⁻ into amino acids, and assimilated (transported) nitrate at the same rate as Anabaena sp. strain 7120. Full expression of nitrate assimilation in the two species occurred within 2.5 h (10 to 14% of their generation times) after transfer to nitrate medium. The induction and continued expression of nitrate assimilation was dependent on protein synthesis. The half-saturation constants for nitrate assimilation and for nitrate and ammonium repression of dinitrogen assimilation have ecological significance with respect to nitrogen-dependent growth and competitiveness of the two Anabaena species.     

Productive hemifusion intermediates in fast vesicle fusion driven by neuronal SNAREs

An in vitro fusion assay uses fluorescence microscopy of labeled lipids to monitor single v-SNARE vesicle docking and fusion events on a planar lipid bilayer containing t-SNAREs. For vesicles and bilayer comprising phosphatidylcholine (POPC, 84-85% by mol) and phosphatidylserine (DOPS, 15% by mol), previous work demonstrated prompt, full fusion (τ_fus = 25 ms). Substitution of 20-60% phosphatidylethanolamine (DOPE) for phosphatidylcholine in the v-SNARE vesicle with either 0 or 20% DOPE included in the t-SNARE bilayer gives rise to hemifusion events. Labeled lipids diffuse into the planar bilayer as two temporally distinct waves, presumably hemifusion of the outer leaflet followed by inner leaflet (core) fusion. The fusion kinetics with DOPE is markedly heterogeneous. Some vesicle/docking site pairs exhibit prompt, full fusion while others exhibit hemifusion. Hemifusion events are roughly half productive (leading to subsequent core fusion within 20 s) and half dead-end. In qualitative accord with expectations from studies of protein-free vesicle-vesicle fusion, the hemifusion rate k_hemi is 15-20 times faster than the core fusion rate k_core, and the fraction of hemifusion events increases with increasing percentage of DOPE. This suggests similar underlying molecular pathways for protein-free and neuronal SNARE-driven fusion. Removal of phosphatidylserine from the v-SNARE vesicle has no effect on docking or fusion.     

Recognition of two Dermatophagoides pteronyssinus-specific epitopes on antigen P1 by using monoclonal antibodies: binding to each epitope can be inhibited by serum from dust mite-allergic patients

Monoclonal antibodies were raised against Antigen P1, the major allergen of the house dust mite (Dermatophagoides pteronyssinus). The majority were Antigen P1 specific, isotype IgG1, and did not react with a comparable D. farinae allergen. These antibodies bound 38 to 50% of 125I Antigen P1 in antigen-binding assays (titer greater than or equal to 1/1,000,000), and the quantities of IgG antibody in ascites were 2 to 4 logs greater than those in polyclonal mouse antiserum or in serum from a mite-allergic patient. Two IgM antibodies showed weak binding to Antigen P1 but reacted strongly with D. pteronyssinus in enzyme immunoassay (titer greater than or equal to 1/100,000). Assessments of the specificity of the IgG antibodies by using two inhibition radioimmunoassays suggested that they were directed against two different epitopes. Antibodies 10B9 F6 and 5H8 C12 were purified by preparative isoelectric focusing (isoelectric points of pI 6.25 and 7.4, respectively) and radiolabeled with 125I. Cross-inhibition experiments, using ascites dilutions to inhibit binding of each radiolabeled antibody to Antigen P1, confirmed that these antibodies recognized two distinct epitopes. Analysis of antibodies from 39 clones/hybrids showed that the majority were directed against the same epitopes as either 10B9 F6 or 5H8 C12 (3 out of 39 [8%] and 29 out of 39 [74%], respectively). None of the monoclonal antibodies significantly inhibited (greater than 10%) human IgE binding to Antigen P1 in the radioallergosorbent test. However, 12 of 14 sera from mite allergic patients inhibited binding by the monoclonal antibodies. One serum from a mite-allergic patient inhibited binding of both 10B9 F6 and 5H8 C12 by greater than 85% and showed parallel inhibition curves. The results suggest that these monoclonal antibodies could be used to assay Antigen P1 in both D. pteronyssinus and house dust extracts. It should also be possible to use monoclonal antibodies in inhibition assays to define the antigenic/allergenic determinants recognized by human IgG and IgE antibodies on this mite allergen.