Purification and identification of placental histaminase

Saline extracts were made from desanguinated human placentae, and histaminase was purified from these extracts by salt fractionation, ion-exchange chromatography on cellulosic adsorbents, and by gel filtration on Sephadex G-200. The Specific Activity of the preparation increased approximately 800- fold from Stage 1 to Stage 6, part of this increase being due to the removal of enzyme inhibitors. Further attempts to resolve Stage 6 enzyme by ion-exchange chromatography and re-cycling gel filtration removed some of the remaining contaminants, but did not result in further increases in Specific Activity. Starch gel electrophoresis of the purest preparation revealed that the enzyme had not been separated from high-molecular weight haptoglobin-methaemoglobin species. A new spectrophotometric test for histaminase was developed from Kapeller-Adler 's (1951) indigo test, which proved unsuitable for the present work. The new test was about 50 times more sensitive than any previous method measuring a common product of oxidative deamination of all substrates. Extinction changes after 24. hr. incubation were linearly related to enzyme concentration. Zeller's criticisms of indigo tests (1956, 1965) could not be substantiated. The new indigo test gave very similar results to the method of Holmstedt and Tham (1959) in almost all applications. Although the oxidation of substrate and the production of hydrogen peroxide proceeded immediately, indigometric assays were subject to an initial delay in indigo oxidation, lasting several hours. The oxidation of indigo by synthetic hydrogen peroxide was not subject to any delayj the mechanisms of indigo oxidation by synthet c hydrogen peroxide and by hydrogen peroxide produced in the enzyme-substrate reaction were not the same. More than the stoichiometric amount of indigo was oxidised in tests using synthetic or enzymic hydrogen peroxide, due to oxidation by atmospheric oxygen, catalysed by substrates and products of the indigo test. No way was found to eliminate, or correct results for, hyper-stoichiometric indigo oxidation, and therefore rates of oxidation of indigo could not be translated into conventional expressions of enzymic activity. The specificity of the purest preparations of placental histaminase was found to resemble that of hog kidney and pea seedling DAO, With supporting evidence from mixed-substrate experiments, it was concluded that histaminase oxidised not only the aliphatic diamines, but also agmatine, benzylamine and histamine. Activity towards histamine could not have been due to any known contaminant. The Michaelis constants for the oxidation of several substrates by placental histaminase were determined. Km for putrescine, and the appearance of an optimal substrate concentration, varied with the assay method employed. The histamine concentration giving optimal activity was lower than that for hog kidney DAO. The pH optima for the activity of placental histaminase towards several substrates were determined. The inhibitor specificity of placental histaminasa resembled that of hog kidney and pea seedling DAO, but was distinct from that of benzylamine oxidase or monoamine oxidase (MAO). Activity towards the aliphatic diamines, but not towards histamine, tended to diminish as the enzyme was purified, unless EDTA wa3 added to the working buffers. The possible significance of metal ions in the activation and inhibition of histaminase was discussed, and it was suggested that discrepancies in earlier reports on the specificity of hog kidney DAO might be due to contamination of enzyme solutions by metal ions. Contamination of the purest preparation by other proteins precluded detailed study of the cofactors of placental histaminase, but the possible involvement of copper and pyridoxal phosphate was discussed. The molecular weight of histaminase x*as probably at least 200,000. The enzyme was much more thermolabile than hog kidney MO, but it was extremely stable at low temperatures in dilute borate buffer, pH 8.6. Priorities for future work were considered to be: (a) Development of a satisfactory assay method for oxidative deamination, (b) Separation of histaminase from haptoglobin-methaemoglobin. (c) Study of the metabolism of aliphatic diamines in normal and pregnant human subjects

Transport of charged aerosol OT inverse micelles in nonpolar liquids

Surfactants such as Aerosol OT (AOT) are commonly used to stabilize and electrically charge nonpolar colloids in devices such as electronic ink displays. The electrical behavior of such devices is strongly influenced by the presence of charged inverse micelles, formed by excess surfactant that does not cover the particles. The presence of charged inverse micelles results in increased conductivity of the solution, affecting both the energy consumption of the device and its switching characteristics. In this work, we use transient current measurements to investigate the electrical properties of suspensions of the surfactant Aerosol OT in dodecane. No particles are added, to isolate the effect of excess surfactant. The measured currents upon application of a voltage step are found to be exponentially decaying, and can be described by an analytical model based on an equivalent electric circuit. This behavior is physically interpreted, first by the high generation rate of charged inverse micelles giving the suspension resistor like properties, and second by the buildup of layers of charged inverse micelles at both electrodes, acting as capacitors. The model explains the measurements over a large range of surfactant concentrations, applied voltages, and device thicknesses

Charging dynamics of aerosol OT inverse micelles

Aerosol OT (AOT) is a commonly used surfactant and charging agent in nonpolar liquids. Properties such as the conductivity of AOT suspensions in nonpolar liquids and the behavior of charged AOT inverse micelles at interfaces have been studied recently, but still little is known about the generation dynamics of charged AOT inverse micelles. In this article, the generation dynamics of charged AOT inverse micelles in dodecane are investigated with transient current measurements. At low applied voltages, the generation rate is sufficiently fast to maintain the equilibrium concentration of charged inverse micelles, such that the current scales proportionally with the applied voltage. However, above a threshold voltage the current becomes limited by the generation of charged inverse micelles. Al2O3‑coated electrodes are used to achieve these high-voltage current measurements while reducing surface generation currents. The dependency of the resulting generation-limited currents with the micelle concentration and the liquid volume is compatible with a bulk disproportionation mechanism. The measured currents are analyzed using a model based on drift, generation, and recombination of charged inverse micelles and the corresponding generation and recombination rates of charged AOT inverse micelles have been determined

Investigation of various types of inverse micelles in nonpolar liquids using transient current measurements

Transient current measurements are used to characterize a wide variety of charge carriers in nonpolar liquids. The transient current method allows us to obtain both the concentration and mobility of charge carriers and therefore also the hydrodynamic radius using Stokes' law. In this article, five different surfactants in dodecane are investigated: OLOA11K, Solsperse13940, Span80, Span85, and AOT. We show that different types of currents are observed depending on the size of the inverse micelles. For large inverse micelles such as for OLOA11K, Solsperse13940, and Span80, the measurement of the transient current is straightforward because of the low steady-state current level. However, for small inverse micelles such as AOT and Span85, the current from the generation of charges is much larger such that high voltages, a small distance between the electrodes, and dielectric coatings on the electrodes are required to measure the signal related to the initially present charged inverse micelles. The estimated hydrodynamic radii of AOT and Span85, the two smallest inverse micelles, are in good agreement with the values reported in the literature. The comparison of the transient currents with simulations indicates that the dynamics of the charge transport are well-understood

Medication taking in people with hip and knee osteoarthritis: An analysis of the English Longitudinal Study of Ageing

Objectives: Osteoarthritis (OA) is a highly prevalent condition seen across primary care services. Although evidence‐based guidelines have encouraged the prescription of medications, including analgesics, for this population, there remains uncertainty as to which types of individuals actually take prescribed or over‐the‐counter medications. The purpose of the present study was to determine whether there is a difference in characteristics between people who take medicines for OA compared with those who do not. Methods: A cross‐sectional analysis of the English Longitudinal Study of Ageing (ELSA) cohort was undertaken. Individuals who reported hip and/or knee OA pain were included. Data on medication taking were self‐reported and collected as part of the ELSA data collection programme. Logistic regression analyses were undertaken to determine the relationship between potential predictors (demographic, pathology‐specific, psychological, social and functional) and whether individuals took medications for their OA symptoms. Results: A total of 654 participants reported OA: 543 medicine takers and 111 nontakers. Individuals who had access to a car (odds ratio [OR]: 56.2; 95% confidence interval [CI]: 3.35 to 941.36), those with a greater duration of hip pain (OR: 5.79; 95% CI: 1.40 to 24.0) and those who achieved 10 chair raises at greater speed (OR: 1.08; 95% CI: 1.03 to 1.14) were more likely to take OA medicines. Conclusions: The study identified predictors for medication taking in individuals with hip and/or knee OA. Strategies are now warranted to provide better support to these individuals, to improve health and well‐being for this long‐term, disabling condition

Through Education & Economic Development

I. Securing Full Share In the Economic Bounty II. Building Momentum Towards Success III. HBCUs as Catalysts For Entrepreneurship IV. The Government As a Collaborato

Brief communication: Evolution of a specific O allele (O1vG542A) supports unique ancestry of Native Americans

In this study, we explore the geographic and temporal distribution of a unique variant of the O blood group allele called O1vG542A, which has been shown to be shared among Native Americans but is rare in other populations. O1vG542A was previously reported in Native American populations in Mesoamerica and South America, and has been proposed as an ancestry informative marker. We investigated whether this allele is also found in the Tlingit and Haida, two contemporary indigenous populations from Alaska, and a pre-Columbian population from California. If O1vG542A is present in Na-Dene speakers (i.e., Tlingits), it would indicate that Na-Dene speaking groups share close ancestry with other Native American groups and support a Beringian origin of the allele, consistent with the Beringian Incubation Model. If O1vG542A is found in pre-Columbian populations, it would further support a Beringian origin of the allele, rather than a more recent introduction of the allele into the Americas via gene flow from one or more populations which have admixed with Native Americans over the past five centuries. We identified this allele in one Na-Dene population at a frequency of 0.11, and one ancient California population at a frequency of 0.20. Our results support a Beringian origin of O1vG542A, which is distributed today among all Native American groups that have been genotyped in appreciable numbers at this locus. This result is consistent with the hypothesis that Na-Dene and other Native American populations primarily derive their ancestry from a single source population. Am J Phys Anthropol 151:649–657, 2013. © 2013 Wiley Periodicals, Inc

Impaired cardiac and skeletal muscle bioenergetics in children, adolescents, and young adults with Barth syndrome

Barth syndrome (BTHS) is an X‐linked condition characterized by altered cardiolipin metabolism and cardioskeletal myopathy. We sought to compare cardiac and skeletal muscle bioenergetics in children, adolescents, and young adults with BTHS and unaffected controls and examine their relationships with cardiac function and exercise capacity. Children/adolescents and young adults with BTHS (n = 20) and children/adolescent and young adult control participants (n = 23, total n = 43) underwent (31)P magnetic resonance spectroscopy ((31)P‐MRS) of the lower extremity (calf) and heart for estimation of skeletal muscle and cardiac bioenergetics. Peak exercise testing (VO (2peak)) and resting echocardiography were also performed on all participants. Cardiac PCr/ATP ratio was significantly lower in children/adolescents (BTHS: 1.5 ± 0.2 vs. Control: 2.0 ± 0.3, P < 0.01) and adults (BTHS: 1.9 ± 0.2 vs. Control: 2.3 ± 0.2, P < 0.01) with BTHS compared to Control groups. Adults (BTHS: 76.4 ± 31.6 vs. Control: 35.0 ± 7.4 sec, P < 0.01) and children/adolescents (BTHS: 71.5 ± 21.3 vs. Control: 31.4 ± 7.4 sec, P < 0.01) with BTHS had significantly longer calf PCr recovery (τ PCr) postexercise compared to controls. Maximal calf ATP production through oxidative phosphorylation (Qmax‐lin) was significantly lower in children/adolescents (BTHS: 0.5 ± 0.1 vs. Control: 1.1 ± 0.3 mmol/L per sec, P < 0.01) and adults (BTHS: 0.5 ± 0.2 vs. Control: 1.0 ± 0.2 mmol/L sec, P < 0.01) with BTHS compared to controls. Blunted cardiac and skeletal muscle bioenergetics were associated with lower VO(2peak) but not resting cardiac function. Cardiac and skeletal muscle bioenergetics are impaired and appear to contribute to exercise intolerance in BTHS

Case report: Basedow paraplegia: A possible misnomer

Thyrotoxic myopathy frequently occurs in clinical practice; however, the association of hyperthyroidism with a flaccid, areflexic paraplegia, so-called Basedow paraplegia, appears to represent a controversial and doubtful entity. An 18-year-old female with undiagnosed and untreated Graves’ disease presented with acute onset of global weakness predominantly in the lower limbs, but also affecting the upper limbs. The weakness was accompanied by hypotonia and areflexia. Clinically, the patient had a goitre and signs of thyroid ocular disease. Laboratory testing confirmed the presence of hyperthyroidism, and thyroid-stimulating hormone receptor antibodies were positive. The cerebrospinal fluid protein level was raised. The electroneuronographic and needle examinations were compatible with a clear denervation process, such as acute motor axonal neuropathy, a variant of Guillain-Barré syndrome. Intravenous immunoglobulin therapy, carbimazole and propranolol were administered. The occurrence of hyperthyroidism with a flaccid, areflexic paraplegia appears to represent more of a fortuitous than a causative association. It is important to consider and treat other causes, such as acute idiopathic polyneuritis