Differential gastric ulceration in rats receiving shocks on either fixed-time or variable-time schedules.

Research suggests that predictable electric shocks produce less stress than unpredictable shocks. In this experiment, predictability was manipulated by using fixed-time (FT, predictable) and variable-time (VT, unpredictable) schedules of shock delivery. Rats receiving 3-mA, 1-s electric shocks on a FT 45-s schedule developed less gastric pathology than another group that was administered identical shocks on a VT 45-s schedule. It is argued that this finding represents a more subtle effect of predictability than has been obtained heretofore. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infrared, surface-assisted laser desorption ionization mass spectrometry on frozen aqueous solutions of proteins and peptides using suspensions of organic solids

Surface-assisted, laser desorption ionization (SALDI) time-of-flight mass spectra of proteins and peptides have been obtained from bulk frozen aqueous solutions by adding solid organic powders to the solutions before freezing. Abundant analyte ions were obtained with a 3.28 microgram Nd:YAG/OPO laser. 20 compounds were evaluated as solid additives, and 16 yielded protein mass spectra. Successful solids included compounds like pyrene, aspartic acid, and polystyrene. The best results were obtained with nicotinic acid and indole-2-carboxylic acid, which yielded protein mass spectra anywhere on the sample and with every laser shot. Compared with ultraviolet-matrix-assisted laser desorption ionization on the same instrument, cryo-IR-SALDI had a comparable detection limit (approximately equal to 1 micro M), a lower mass resolution for peptides, and a higher mass resolution for large proteins. Approximately 2500 cryo-IR-SALDI mass spectra were obtained from a single spot on a 0.3-mm-thick frozen sample before the metal surface was reached. About 0.1 nL of frozen solution was desorbed per laser shot. The extent of protein charging varied between the SALDI solids used. With thymine, myoglobin charge states up to MH12(+12) were observed. It is tentatively concluded that observed ions are performed in the frozen sample.     

Differential precipitation of copper and nickel from acidic polymetallic aqueous solutions

During the pyrometallurgical treatment of copper concentrates several wastes (gaseous, solid and liquid) are generated. Wastewaters produced in a primary copper smelter are acidic polymetallic solutions characterized by intermediate to high sulphuric acid concentration. Additionally, they usually contain large quantities of valuable metals, such as Cu and Ni, as well as impurities, such as Pb, Zn, Fe, As, Sb, Bi, etc. Therefore, recovery of valuable metals from acidic polymetallic aqueous solutions is of great importance for every plant. This paper is dealing with the recovery of copper and nickel from the acidic polymetallic solutions generated in the copper smelter at Bor, Serbia. The process of differential precipitation of metals through neutralization with caustic soda was selected as the treatment alternative that combines simplicity, efficiency and reliability with low capital and maintenance costs. The concept was based on the development of a simple and efficient process that could be more attractive for industries located in countries suffering from economic recession. Theoretical analysis and experimental results showed that copper and nickel can be differentially removed from the acidic polymetallic solutions at pH = 7 and pH = 10, respectively, mainly contaminated by arsenic, which occurs at high concentrations in acidic polymetallic solutions. Both metals were precipitated as hydroxides, although a small portion of copper was removed also as copper sulfate salt. The resulted precipitates are rich in copper and nickel and can be recycled in copper, as well as in nickel smelters.     

Differential electrophoretic behavior in aqueous polymer solutions of red blood cells from Alzheimer patients and from normal individuals

The recently reported phenomenon that red blood cells (RBC) from Alzheimer disease (AD) patients and normal individuals, which have identical electrophoretic mobilities (EPM) in phosphate-buffered saline (PBS), have different EPM in appropriately selected polymer solutions, has been further explored. Of a number of in vitro treatments to which AD and normal RBC were subjected prior to EPM measurements in bottom phase (from a dextran-poly(ethylene glycol) (PEG) aqueous phase system) only trypsin eliminated the difference. Thus, the differential polymer interaction between AD and normal RBC, thought to be the basis for their dissimilar EPM, can be abolished by appropriate proteolytic modification of the cell surfaces and suggests protein as a source of difference. Because young and old RBC from normal individuals, which have the same EPM in PBS, have different EPM in certain polymer solutions, and the RBC from AD patients have been reported to age abnormally, we also compared the young and old RBC subpopulations from these two sources. By the criterion of cell electrophoresis in polymer solutions the differences between AD and normal RBC and between young and old RBC are distinct. The EPM of AD and normal RBC differ in bottom phase or PEG but not in dextran solution; while the EPM of young and old RBC differ predominantly in dextran. We speculate that since the observed difference in EPM of RBC from AD patients and normals depends on protein(s) yet is anticoagulant-related (being obtained only when blood is collected in citrate or oxalate) it might be the result of an interaction (Ca(2+)-mediated?) between the surfaces of these cells and protein component(s) of their respective, compositionally differing sera.     

Gamma-irradiation of malic acid in aqueous solutions

The gamma-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the non-volatile products. Thin layer chromatography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the gamma-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.     

Solubility of oxygen in aqueous electrolyte solutions

The solubility of oxygen in a number of aqueous electrolyte solutions was determined using a colorimetric method based on the oxidation of indigo carmine. The effects of changes in electrolyte concentration, temperature and partial pressure of oxygen were investigated.The ratio of the solubility of oxygen in the electrolyte solutions to that in pure water decreases as the concentration of the electrolyte increases but is essentially independent of both temperature (over the range 298–348 K) and the oxygen partial pressure (over the range 0.1–1.0 atm).Empirical relationships for this solubility ratio as a function of the electrolyte concentration and temperature were developed. The predictions made using these relationships are found to be superior to the alternative methods suggested in the literature, particularly for those conditions frequently found in hydrometallurgical systems, namely at high electrolyte concentrations.The significance of changes in the solubility of oxygen in aqueous electrolyte solutions is briefly discussed with particular reference to the hydrometallurgical implications.     

Electrocrystallization of copper in chloride aqueous solutions

An apparatus was built in our laboratory in order to electrolyze a Gokhale solution (CuC10.7N,NaC14N, HC10.5N)for extended periods of time under current densities ranging from 50 to 600 A/m² at temperatures between 20 and 50°C The influence of the diaphragm, temperature, current density and duration of the electrolysis in pure solutions was investigated, and the results were interpreted in terms of current efficiency, overall voltage drop and specific energy consumption. The structure of the deposits was investigated by profilometry, optical micrography, scanning electron microscopy and X-ray diffraction. The structure of the deposits is not significantly different from that obtained in pure sulfuric acid solutions, but it shows an increased tendency to growth of rather large elongated crystals protruding in the electrolyte. Both types are characteristic of deposits obtained at rather low inhibition, according to Fischer’s classification. Formerly Researcher, Université Libre de Bruxelles     

The extraction of copper from dilute aqueous solutions using a liquid membrane process

A liquid surfactant membrane process is considered for the separation of copper ions from dilute aqueous solutions. The process is shown to work effectively, solutions ranging in concentrations from 2000 ppm copper as copper sulphate (typical of acid leach solutions) down to 100 ppm copper have been successfully processed. In the case of the very dilute solutions the copper concentration in the final raffinate can be taken down to less than 1 ppm in a single contact stage. The liquid membrane is made up of a chelating agent, in this work Shell SME 529, organic diluent and emulsifying agent. Factors influencing mass transfer, such as membrane composition, O/A ratio, pH of the aqueous feed solution and acid content of the strip solution, contacting condition etc., have been studied. Providing membrane breakdown is low the process can be represented as a pseudo first order rate process. It is shown that by using this form of facilitated transport transfer of copper ions against very adverse concentration gradients across the membrane can be achieved. Further pilot plant work is required to examine scale up features of this process. Compared with conventional solvent extraction the amount of solvent (reagent and diluent) required in the contacting stage(s) is very much reduced. In this work it is shown that successful extraction of copper can be achieved using over two orders of magnitude less solvent than with solvent extraction.     

Estimations of average particle sizes and size distributions of commercially available human-insulin aqueous suspensions using laser-light diffraction spectroscopy

The average diameter and size distribution of particles in commercially available isophane-insulin and zinc-insulin aqueous suspensions (11 products) were examined using laser-light diffraction spectroscopy (LLDS). Wide variation was observed between products in volume-weighted and number-weighted average diameters. The particles in the insulin aqueous suspensions were found to be mono-dispersed within relatively narrow size distributions. Sonication for a short time led to a downshift in the apparent average diameter, which was most remarkable with isophane-insulin aqueous suspensions. This could be ascribed to dispersion of aggregated needle-like crystals and/or crystal breakage. In the case of biphasic isophane-insulin aqueous suspensions, the average size as well as the size distribution shifted toward the smaller end of the scale with decrease in the isophane content.     

Consistent lack of association between breast cancer and oral contraceptives using either hospital or neighborhood controls

BACKGROUND: Case-control studies of oral contraceptive use and breast cancer have used neighborhood, population, or hospital controls. METHODS: To determine whether this association differs according to type of controls, interview data from 131 incident cases of breast cancer were compared with those of 189 hospital controls and 182 neighborhood controls Study subjects were white females recruited between 1973 and 1975 from among residents of Baltimore City and County ages 18 to 59 years. RESULTS: Adjusted relative odds of breast cancer related to ever versus never use of oral contraceptives were 1.0 and 0.8, using hospital and neighborhood controls, respectively. Relative odds did not increase proportionally to duration of oral contraceptive use or to progestogen potency. Although few subjects had used oral contraceptives for more than 2 years, almost all pill brands contained more than 49 micrograms of ethinyl estradiol or of mestranol. CONCLUSIONS: Results from the present study do not support the hypothesis that early preparations of oral contraceptives increased breast cancer risk among white women, regardless of whether controls are neighbors of the cases or hospital patients. However, its conclusions cannot be generalized to women who began taking the pill before their first full-term birth or took it for more than 2 years.     

A comparative study of fixation techniques in the open Bankart operation using either a cannulated screw or suture-anchors

Neuroendocrine PC12 cells contain small microvesicles that closely resemble synaptic vesicles in their physical and chemical properties. Two defining characteristics of synaptic vesicles are their homogeneous size and their unique protein composition. Since synaptic vesicles arise by endocytosis from the plasma membrane, nerve terminals and PC12 cells must contain the molecular machinery to sort synaptic vesicles from other membrane proteins and pinch off vesicles of the correct diameter from a precursor compartment. A cell-free reconstitution system was developed that generates vesicles from PC12 membrane precursors in the presence of ATP and brain cytosol and is temperature dependent. At 15 degrees C, surface-labeled synaptic vesicle proteins accumulate in a donor compartment, while labeled synaptic vesicles cannot be detected. The block of synaptic vesicle formation at 15 degrees C enables the use of the monoclonal antibody, KT3, a specific marker for the epitope-tagged synaptic vesicle protein, VAMP-TAg, to label precursors in the synaptic vesicle biogenesis pathway. From membranes labeled in vivo at 15 degrees C, vesicles generated in vitro at 37 degreesC had the sedimentation characteristics of neuroendocrine synaptic vesicles on glycerol velocity gradients, and excluded the transferrin receptor. Therefore, vesiculation and sorting can be studied in this cell-free system.     

Kinetics and toxicity of liposomal and conventional amikacin in a patient with multidrug-resistant tuberculosis

The pharmacokinetics and toxicity of liposomal amikacin in a patient treated for advanced pulmonary multidrug-resistant tuberculosis are described. A dose of 20 mg/kg of liposomal amikacin was given on alternate days for 14 days and weekly thereafter for 9 weeks, for a total dose of 20.1 g in 17 divided doses. Accumulation occurred with alternate-day, but not weekly, dosing. The serum levels of amikacin obtained with the liposomal preparation were considerably greater than those obtained with the conventional preparation (range, 81-457 mg/l vs. 4.1-37.7 mg/l). The liposomal amikacin was well tolerated and led to clinical improvement, but it failed to achieve a microbiological response. The patient's sputum remained smear- and culture-positive during the treatment period with liposomal amikacin and for 9 months afterward.     

Dissolution of nickel hydroxide in ammoniacal aqueous solutions

The dissolution of nickel hydroxide in ammoniacal solutions was investigated to develop a new recycling process for nickel-metal hydride batteries. The effects of temperature, total ammonia concentration, and pH of the solution were examined in the range of 30 °C to 60 °C, 3.0 to 5.0 M, and 9.0 to 10.7, respectively. All dissolution-time curves showed sigmoidal shapes, which could be approximately expressed by the Johnson-Mehl-Avrami-Yerofeev-Kolmogrov (JMAYK) equation. The hydroxide particles were pitted, and some of them were broken into fragments in the course of the dissolution. An increase in the surface area of the hydroxide particles due to the formation of pits and fragmentation seemed to be the reason for the acceleration of dissolution in the early stage. The surface area of the hydroxide was measured by the Brunauer-Emmett-Teller (BET) method, and the dissolution rate per surface area was determined. The activation energy for the dissolution was obtained as 100±10 kJ mol⁻¹, which confirmed that the dissolution was controlled by chemical reactions at the hydroxide/liquid interface. The dissolution rate was increased by the increase in ammonia concentration, and the highest rate was observed at pH ca. 10.     

Uptake of Zn2+ from dilute aqueous solutions using protonated dry alginate beads

The uptake of zinc ions from dilute aqueous solutions was studied at 25°C using protonated dry alginate beads (PDAB) of around 1 mm in diameter. The Zn²⁺ uptake increases with the pH of the Zn bearing solution, reaching a value of around 90 mg of Zn per gram of beads (dry weight) at pH 4·5. For an initial Zn concentration as low as 10 mg L^?1, the removal reached was complete.

The mechanism of Zn uptake was found to be ion exchange between zinc ions and protons form the functional groups of the beads, which followed a pseudo-second order kinetic behaviour. In equilibrium condition the experimental data followed the Langmuir adsorption model.

The maximum uptake reached were around 145 and 165 mg g^?1 at pH values of 3·5 and 4·5, respectively, which is higher than most of the sorbents used for zinc removal. EPMA-EDX analysis shows that the functional groups of the PDAB were homogeneously distributed during preparation of beads, and that zinc ions were able to reach functional groups in the entire structure of the beads without a concentration gradient across the beads.

On a étudié le changement d′ions de le Zinc depuis des solutions aqueuses diluées à 25°C en utilisant des sphères protonadas sèches d′alginatos (PDAB) d′autour de 1 mm de diamètre. Le changement de Zn²⁺ augmente avec le pH de la solution, en atteignant une valeur d′autour de 90 mg de Zn par gramme de sphères (un poids sec) à un pH 4.5. Pour un concetración initial de Zn plus bas que 10 mg L^?1, le changement à court d'argent a été complet. Le mécanisme de changement de Zn est été par un échange ionique entre des ions de zinc et protones provenants depuis les groupes fonctionnels des sphères, qui a un comportement cinétique du pseudo-deuxième ordre. Dans des conditions d′équilibre, les données expérimentales suivent un modèle d′adsorpcin de Langmuir. Le changement maximal à court d′argent a été de 145 et 165 mg g^?1 aux valeurs de pH de 3.5 et 4.5, respectivement, où elles ont été plus hautes que les sorbentes utilisés pour le changement de Zn. Des analyses par EPMA-EDX ont montré que les groupes fonctionnels du PDAB ont été distribués de façon homogène durant la préparation des sphères, et que les ions de zinc ont été capables d′atteindre les groupes fonctionnels dans toute la structure des sphères sans une pente de concentration à travers des sphères.     

Differential modulation of changes in hippocampal-septal synaptic excitability by the amygdala as a function of either elemental or contextual fear conditioning in mice

Recent data obtained using a classic fear conditioning paradigm showed a dissociation between the retention of associations relative to contextual information (dependent on the hippocampal formation) and the retention of elemental associations (dependent on the amygdala). Furthermore, it was reported that conditioned emotional responses (CERs) could be dissociated from the recollection of the learning experience (declarative memory) in humans and from modifications of the hippocampal-septal excitability in animals. Our aim was to determine whether these two systems ("behavioral expression" system and "factual memory" system) interact by examining the consequences of amygdalar lesions (1) on the modifications of hippocampal-septal excitability and (2) on the behavioral expression of fear (freezing) resulting from an aversive conditioning during reexposure to conditional stimuli (CSs). During conditioning, to modulate the predictive nature of the context and of a discrete stimulus (tone) on the unconditional stimulus (US) occurrence, the phasic discrete CS was paired with the US or randomly distributed with regard to the US. After the lesion, the CER was dramatically reduced during reexposure to the CSs, whatever the type of acquisition. However, the changes in hippocampal-septal excitability persisted but were altered. For controls, a decrease in septal excitability was observed during reexposure to the conditioning context only for the "unpaired group" (predictive context case). Conversely, among lesioned subjects this decrease was observed in the "paired group" (predictive discrete CS case), whereas this decrease was significantly reduced in the unpaired group with respect to the matched control group. The amplitude and the direction of these modifications suggest a differential modulation of hippocampal-septal excitability by the amygdala to amplify the contribution of the more predictive association signaling the occurrence of the aversive event.