Tenfold Increase In Concentration Research Articles

Hg(II) Ion-Selective Electrodes with PVC Membranes Based on Bis-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one

Abstract A new solid-state contact potentiometric membrane electrode was developed based on bis-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (ionophore), which acts selectively towards the mercury(II) ion. The ionophore was synthesized by the treatment of an amino derivative with oxybis dibenzaldehyde. The potentiometric behavior of an electrode was investigated in the concentration range from 1.0 × 10−2 to 1.0 × 10−6 mol L−1 for mercury(II) ion. The electrode displayed a good linearity (R2 = 0.9997) with the detection limit of 1.2 × 10−7 mol L−1 and showed a very high selectivity against Hg(II) ion without being affected by the presence of interfering ions. The electrode exhibited a potential change of 62.0 ± 2.0 mV for each ten-fold increase in concentration of mercury(II) ion. Potentiometric response of the electrode was investigated in the pH range from 3.0 to 10.0. In addition to this electrode being used to determine mercury(II) in different water samples, it can also be used with EDTA as an indicator electrode in the potentiometric titration of mercury(II) ion. Since the developed electrode displayed good potentiometric performance, it has potential to be used in environmental and biological samples for detection of mercury(II) ions.

Lack of Humoral Immunity Against Glucosaminidase Is Associated with Postoperative Complications in Staphylococcus aureus Osteomyelitis.

Glucosaminidase (Gmd) is known to be a protective antigen in animal models of Staphylococcus aureus osteomyelitis. We compared the endogenous anti-Gmd antibody levels in sera of patients with culture-confirmed S. aureus bone infections to their sera at 1 year after operative treatment of the infection. A novel global biospecimen registry of 297 patients with deep-wound culture-confirmed S. aureus osteomyelitis was analyzed to assess relationships between baseline anti-Gmd serum titers (via custom Luminex assay), known host risk factors for infection, and 1-year postoperative clinical outcomes (e.g., infection control, inconclusive, refracture, persistent infection, septic nonunion, amputation, and septic death). All patients had measurable humoral immunity against some S. aureus antigens, but only 20 patients (6.7%; p < 0.0001) had high levels of anti-Gmd antibodies (>10 ng/mL) in serum at baseline. A subset of 194 patients (65.3%) who completed 1 year of follow-up was divided into groups based on anti-Gmd level: low (<1 ng/mL, 54 patients; 27.8%), intermediate (<10 ng/mL, 122 patients; 62.9%), and high (>10 ng/mL, 18 patients; 9.3%), and infection control rates were 40.7%, 50.0%, and 66.7%, respectively. The incidence of adverse outcomes in these groups was 33.3%, 16.4%, and 11.1%, respectively. Assessing anti-Gmd level as a continuous variable showed a 60% reduction in adverse-event odds (p = 0.04) for every tenfold increase in concentration. No differences in patient demographics, body mass index of >40 kg/m, diabetes status, age of ≥70 years, male sex, Charlson Comorbidity Index of >1, or Cierny-Mader host type were observed between groups, and these risk factors were not associated with adverse events. Patients with low anti-Gmd titer demonstrated a significant 2.68-fold increased odds of adverse outcomes (p = 0.008). Deficiency in circulating anti-Gmd antibodies was associated serious adverse outcomes following operative treatment of S. aureus osteomyelitis. At 1 year, high levels of anti-Gmd antibodies were associated with a nearly 3-fold increase in infection-control odds. Additional prospective studies clarifying Gmd immunization for osteomyelitis are needed. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Oxidation of phenol and chlorophenols on platinized titanium anodes in an acidic medium

A comparative study of oxidation of phenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol on Pt/Ti and Ce,Pt/Ti electrocatalysts is performed via cyclic voltammetry. It is shown that the surface morphology and roughness of the anode do not change after modification with cerium. The formal kinetic orders of electrooxidation of all compounds are found to be less than one. It is shown that the β temperature coefficients of the rate of oxidation of chlorophenols grow by 10 to 50% when the Ce,Pt/Ti anode is used at a substrate concentration of 1 mM. A tenfold increase in concentration reduces the effect of cerium additive, except for 3-chlorophenol: the latter exhibits a 250% increase in the β value, compared to the Pt/Ti anode.

Features of Urine Biomineralization in Long-Livers

The increasing number of long-livers in the developed countries indicates the demand for clarification of the body vital systems' functioningfeatures which allow the long-livers to prolong their active involvement in social life. Aim of our study/research was to define a functional condition of urinary system in long-livers using the new diagnostic technology which analyses the structures of biological liquid at its phase transition in a solid state. A case series study was held. All long-livers suffered from atherosclerosis and its complications as well as from associated diseases. An exclusion criterion was acute conditions. The creatinine level in blood serum, indicators of common urine analysis and features of urine facies (using cuneiform dehydration) were defined. Participants included 60 long-livers (mean age 87.34±4.17 years) who were passing clinical laboratory tests at in-patient department of gerontological hospital. In urine facies of 41 (68.3%) long-livers a phenomenon of salt crystals distribution was identified. It presents the concentration of anisotropic salt crystals in the form of a ring in a regional facies zone. The tenfold increase in concentration of calcium and double increase in concentration of phosphorus in comparison with the central zone was detected in long-livers with a higher percent sulphur in the regional zone of urinefacies. The urine facies of the majority of long-livers have signs of age structure formation associated with a specific distribution of anisotropic salt crystals which fix detritus in its inert form to block the autointoxication.

Properties of an interfacial solution layer at gold electrode surface in perchlorate and chloride solutions: piezoelectric resonator and drag force study

Piezoelectric resonator and drag force measurements show a decrease of interfacial viscosity of perchlorate and chloride aqueous solutions during polarization of gold electrode towards potential of zero charge. Though more noisy, drag force measurements have the advantage over piezoelectric technique as the former is insensitive to potential dependent adsorption, which causes distortion of data on liquid properties obtained from piezoelectric resonator measurements at more positive potentials. The shift in the potential of the viscosity minimum, obtained from drag force measurements follows the shift in the potential of zero charge (pzc) with a change in concentration. In addition, the Esin-Markov relation holds at these potentials: tenfold increase in concentration of specifically adsorbing chloride shifts the potential of viscosity minimum by -46mV, whereas tenfold increase in concentration of weakly adsorbing perchlorate results only in the negligible shift of the potential of viscosity minimum (-4mV).

Preliminary Studies on the Aggregation Process of Alpha-Crystallin

The mechanism by which α-crystallin subunits form the native 800 kD aggregate is currently unknown. Experiments were performed to investigate the mechanism for this process. Gel-filtration Fast Performance Liquid Chromatography (FPLC) and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE), with and without cross-linking with glutaraldehyde, indicate that α-crystallin undergoes a concentration-dependent aggregation process. The denaturation of α-crystallin, and its subsequent renaturation and reaggregation, lead to the formation of several different species. At very low concentrations (< 0.5 μm), only monomeric and/or dimeric species exist. With a ten-fold increase in α-crystallin concentration from 0.05 μmto 0.5 μm, the amount of the monomeric/dimeric species increases to a plateau coincident with the appearance of a tetrameric species at 0.5 μm. With an additional ten-fold increase in concentration from 0.5 μmto 5 μm, the amount of the tetrameric species increases and levels off to its own plateau coincident with the appearance of the native 800 kD α-crystallin aggregate at 5 μm. The amount of the native species is extremely small at this concentration, but increases sharply and linearly with increasing concentration, while the concentrations of monomeric/dimeric and tetrameric species remain constant. The concentration at which the relative amount of the native species begins to increase sharply is within the range of the critical micelle concentration previously characterized.

Reverse osmosis as a concentration technique for soluble organic phosphorus in fresh water

The chemical nature and availability of soluble organic phosphorus for algal growth is largely unknown. A commercially available reverse osmosis water purification system was adapted for concentrating the soluble organic phosphorus fraction form 100-l volumes of drainage water collected from tile drains underlying an intensively managed grassland area in the Lough Neagh catchment. After membrane filtration the drainage water was recirculated through the reverse osmosis module while the permeate was removed from the system. During a single passage across the reverse osmosis membrane, 20% of the sample was discarded as pure water while the remaining 80% of the sample was pumped back to the reverse osmosis cartridge. Recirculation was continued, with the addition of an intermediate sodium ion-exchange step to prevent the precipitation of insoluble (largely calcium and magnesium) salts, until the volume was reduced to 2.5 l. The recovery of soluble organic phosphorus based on the original sample concentration was almost 93%. A further tenfold increase in concentration was achieved without salt precipitation or loss of soluble organic phosphorus by vacuum-assisted rotary evaporation. The mild, efficient concentration process developed a soluble organic phosphorus concentrate suitable for chemical fractionation and algal availability studies.

Synthesis and characterization of polyantimonic acid membranes

Membranes consisting of polyantimonic acid and an organic binder have been manufactured by a film-casting technique. Polyvinylidene fluoride and polysulfone have been used as the organic binder material. The thickness of these film-casted membranes was 0.1–0.3 mm. Several membrane characteristics such as ionic conductance, membrane potential and Hittorf transference numbers have been measured in different experimental set-ups. The temperature dependence of the membrane conductance exhibits an exponential decay when working in an alkaline solution (1N KOH). Activation energies on the order of 0.17–0.18 eV have been calculated for this ionic conduction process. The cation transference numbers E +, as determined from permselectivity measurements in different aquous KOH solutions, show a gradual decrease from about 0.8 towards 0.5 for a tenfold increase in concentration (0.1→1 N). The actual performance of the polyantimonic acid membranes under water-electrolysis conditions has been measured, and cell voltages of about 2 Volts at high current densities (8–10 kAm -2) and at temperatures below 100 °C could be obtained.

Black root rot development in cotton roots caused by Thielaviopsis basicola and the possible rôle of methyl acetate in pathogenesis

Fusel oil components produced in vitro by Thielaviopsis basicola were: methyl acetate, ethyl acetate, ethyl alcohol, propyl acetate, propyl alcohol, isobutyl alcohol, isoamyl acetate and isoamyl alcohol. With the exception of methyl acetate and propyl alcohol all fusel oil components produced by T. basicola have been reported previously. Methyl acetate was identified by gas-liquid chromatography and by gas-liquid chromatography-mass-spectrometry in fungal and cotton root extracts. In diseased cotton roots methyl acetate was found in amounts that were 10 times greater than in healthy roots. Studies on the phytotoxicity of methyl acetate to cotton roots showed that a concentration of methyl acetate as low as 0·126 m m caused browning of tissues and other symptoms typical of black root rot. When a possible relationship was tested between the in vitro production of methyl acetate and isoamylalcohol by T. basicola and virulence of T. basicola in cotton, no apparent association was found. Mutant isolates of T. basicola, which produced either more or less of methyl acetate and/or isoamyl alcohol than their highly virulent parent did not differ from their parent in the severity of black root rot they caused in cotton roots. Associated with the development of black root rot was a marked increase in peroxidase activity. The phytotoxicity of methyl acetate and its tenfold increase in concentration in diseased roots compared with healthy roots suggest a possible rôle of methyl acetate in pathogenesis.

Membrane potentials of epithelial cells in the epididymis of rats. Ionic and castration effects

1. 1. Membrane potentials were measured from rat epididymal epithelial cells in vitro at 35°C using micro-electrodes. The values obtained from the caput epididymis and the cauda epididymis were respectively −21.10 ± 0.26 mV (mean ± S.E. N = 470) and −30.53 ± 0.74 mV (mean ± S.E. N = 315). 2. 2. An increase in external potassium concentration depolarized the cells in both regions, a ten-fold increase in concentration causing a depolarization of 12mV in the caput and 22 mV in the cauda. 3. 3. Removal of sodium from the bathing solution caused a significant hyperpolarization in both regions as did treatment of the cells with amiloride (10 −4M). 4. 4. Ouabain (10 −3M) and 2,4-dinitrophenol (2.5 × 10 −4M) depolarized the cells in both regions. 5. 5. Castration caused a decrease in the membrane potentials which could be reversed by replacing rats with testosterone propionate (2 mg/kg per day), indicating that membrane potentials in the cauda epididymis were dependent on the supply of circulating androgens.

Effects of calcium ion on the rising phase of the action potential in rabbit sinoatrial node cells.

To clarify the role of Ca ion in the rising phase of the sinoatrial (S-A) node action potential, the sigmoidal relationship between the maximum rate of rise of the action potential and the maximum diastolic potential was examined at various concentrations of Ca. The membrane potential was changed by applying a current across a single sucrose gap. The sigmoidal curve shifted toward the positive potential without a change in maximum value when the Ca concentration was increased from nominal "zero" to 10 mM. Therefore, it is concluded that Ca ion modifies the inactivation process of Na current which is responsible for the rapid rising phase of the S-A node action potential. The duration of the action potential and the maximum diastolic potential were decreased with an increase in Ca concentration. The observation that the overshoot of the action potential increased by 12 mV for a tenfold increase in concentration of Ca (within the range of 0.1-5.0 mM) suggests that the inward current of Ca ion may be responsible for the overshoot of the S-A node action potential.

Intracellular potentials in cells of the seminiferous tubules of rats.

1. Membrane potentials have been recorded from cells of seminiferous tubules of rats in vitro using micro-electrodes. The value in 808 impalements was -28-2 +/- 0-3 mV (mean +/- S.E.) at 33 degrees C. 2. Increasing the potassium concentration depolarized the cells, a tenfold increase in concentration causing a depolarization of 16 mV. Removal of sodium from the bathing solution caused a hyperpolarization of 3 mV at a potassium concentration of 5-9 m-equiv/l. Removal of chloride and replacement with impermeant anions had no effect on potential. Removal of calcium from the bathing solution caused a minor but significant depolarization. 3. Ouabain (10-3 M), dinitrophenol (2-5 times 10-4 M) or removal of glucose from the bathing fluid all caused depolarization. The membrane potentials of the cells were sensitive to temperature over the range 10-33 degrees C, the apparent activation energy for the reactions maintaining the potential being approximately 6 kcal/mole. 4. Membrane potentials in seminiferous tubules were independent of age of the animal, were insensitive to previous hypophysectomy and were insensitive to a number of hormones (FSH, LH, HCG, oxytocin). In high concentration prostaglandin E1 caused depolarization. 5. Acetazoleamide (4 times 10-5 M) caused a rapid, but reversible, depolarization of the tubular cells. This was also true in conditions when the HCO'3/CO2 buffer system was replaced with Tris-buffer. Another carbonic anhydrase inhibitor (p-sulphonamido-benzoic acid) had similar effects on cell potentials as acetazoleamide. These results are discussed in relation to the nature of the ionic secretion produced in the tubules. 6. Occasional cells showed phasic variations in membrane potential. A possible connexion between these variations and the contractile activity of the tubules is discussed.

Possible screening of surface charges on crayfish axons by polyvalent metal ions.

1. The effect of different polyvalent metal ions in the external solution upon the threshold membrane potential for spike initiation in crayfish axons has been studied by means of intracellular micro-electrodes. The metal ions tested included six divalent cations (Ca(2+), Mg(2+), Sr(2+), Ba(2+), Co(2+), and Ni(2+)) and three trivalent cations (La(3+), Y(3+) and Eu(3+)).2. Identical extracellular concentrations of different cations with the same valence had essentially the same effect on threshold membrane potential. However, a very low concentration of trivalent cations (about 225 muM) was found to be equivalent to a much higher divalent cation concentration (13.5 mM) as measured by their effects on threshold potential.3. Upon a tenfold increase in concentration, the threshold potential for spike initiation was shifted in a positive direction by 30.6 mV with divalent cations and by 20.8 mV with trivalent cations.4. It is shown that a hypothesis involving screening of negative charges at the axonal membrane surface, based on Gouy-Chapman theory, predicts these various experimental results rather closely.5. It is concluded that a high negative charge density, sufficient to render a screening mechanism possible, exists at the surface of crayfish axons in the region of the sodium ;gates'.6. The density of surface charges is calculated to be approximately 1e(-)/43 A(2). This calculation is discussed in connexion with the possible molecular identity of the sodium ;gates' in crayfish axons and other excitable systems.

The clam-heart bioassay for acetylcholine

1. 1. The clam-heart bioassay, originally introduced by J. H. Welsh in 1943, is sensitive, specific and convenient. An accuracy of better than ± 10 per cent can be readily accomplished by matching the reduction in amplitude of the ventricular beat produced by known concentrations of acetylcholine (ACh) and by tissue extracts. 2. 2. The isolated ventricle is mounted in a bath of known volume and the contractions are recorded on a kymograph or by means of a mechanoelectric transducer on a chart recorder. 3. 3. Ach standards are made up in buffered saline of pH 6·5. The procedure consists of the following steps: (1) establishment of the range of sensitivity of the test ventricle; (2) establishment of the range of effects of applying ACh concentrations in ten steps of 20 per cent difference, covering a tenfold increase in concentration; (3) the bioassay proper in which known and unknown ACh concentrations are matched. 4. 4. Methods are described for detecting interfering substances in tissue extracts and for establishing that the detected activity is indeed due to ACh. These involve use of pharmacological (blocking agents), enzymatic (cholinesterase) and chromatographic procedures. 5. 5. Examples are given of the method of calculating the data and determining the degree of accuracy of individual determinations. 6. 6. A table summarizes the relative sensitivity of clam ventricles to a variety of cholinesters. Acetylcholine is by far the most active of sixteen related compounds.