Measurement of adrenolutin as an oxidation product of catecholamines in plasma

Using the reverse phase high-performance liquid chromatography (HPLC) with mobile phases composed of simple acids, we have developed an assay technique for the measurement of adrenolutin, one of the oxidation products of catecholamines, in rat plasma. Ion-pairing chromatography permits the separation and quantitation of plasma adrenolutin (M) in a linear manner. Sample preparation involved the precipitation of plasma proteins with perchloric acid and it is easier to handle a large number of samples at a time. However, we were unable to demonstrate the presence of adrenochrome, another oxidation product of catecholamines, in plasma since adrenochrome was rapidly destroyed in acid as well as in blood and was quickly changed, into adrenolutin. Adrenolutin peak in HPLC was confirmed by 1) the retention time; 2) co-injection of adrenolutin and; 3) the appearance of ³H-adrenolutin after injection of ³H-norepinephrine. Administration of different catecholamines as well as adrenochrome and adrenolutin in rats also increased the level of adrenolutin in plasma. Adrenolutin was found to be present in plasma in other species including dog, rabbit and pig. High level of adrenolutin, which may represent total concentration of aminolutin in plasma, suggests the presence of an efficient mechanism for the oxidation of catecholamines under in vivo conditions.     

Periodic electric field as a biopolymer conformation switch: a possible mechanism

A theoretical model is proposed to describe the influence of a periodic electric field (PEF) upon a biopolymer. The biopolymer is treated as a classical mechanical system consisting of subsystems (molecular groups) which interact with each other through potential forces. The PEF is treated as a periodic driving force applied to a molecular group. The energy dissipation is considered using the model of fluid (viscous) friction. Arguments for the non-linear character of the friction-velocity dependence caused by the non-Newtonian rheology of a viscous medium are formulated.A forced molecular-group motion is investigated for the situation of a small driving-force period, with oscillations overdamped and a driving force consisting of more than one harmonic. As a result, it is established that the motion always gets to a terminal stage when only a small-scale vibration about some point, X ^*, takes place. The terminal motion is preceded by a transient characterized by the presence of a directional velocity component and so by a drift along a potential profile. the drift goes on until a barrier is met which has a sufficiently large steepness (the barrier height is not important). As a result, the point X ^* may happen to be remote from the conformation potential local minimum (conformational state). The physical reasons for the drift are described.If we consider the small-scale vibration about X ^* in the framework of the hierarchy of scales for intramolecular mobility, it can be regarded as an equilibrium mobility, whereas the drift can be regarded as a functionally important motion, and X ^* as a new conformational state which is realizable only in the presence of the PEF. It may be concluded, as the result of a consistent treatment and neglecting the small-scale vibration, that the conformational potential is modified by adding a linear term (in the one-dimensional case). In this connection, the set of conformational states can both deform (deviation of the positions of minima and their relative depth) and rearrange qualitatively (some minima can vanish and/or new minima can appear). In particular, the transition from one conformation to another one may happen due to rearrangement.     

Methanol metabolism in thermotolerant methylotrophic Bacillus strains involving a novel catabolic NAD-dependent methanol dehydrogenase as a key enzyme

The enzymology of methanol utilization in thermotolerant methylotrophic Bacillus strains was investigated. In all strains an immunologically related NAD-dependent methanol dehydrogenase was involved in the initial oxidation of methanol. In cells of Bacillus sp. C1 grown under methanol-limiting conditions this enzyme constituted a high percentage of total soluble protein. The methanol dehydrogenase from this organism was purified to homogeneity and characterized. In cell-free extracts the enzyme displayed biphasic kinetics towards methanol, with apparent K _m values of 3.8 and 166 mM. Carbon assimilation was by way of the fructose-1,6-bisphosphate aldolase cleavage and transketolase/transaldolase rearrangement variant of the RuMP cycle of formaldehyde fixation. The key enzymes of the RuMP cycle, hexulose-6-phosphate synthase (HPS) and hexulose-6-phosphate isomerase (HPI), were present at very high levels of activity. Failure of whole cells to oxidize formate, and the absence of formaldehyde-and formate dehydrogenases indicated the operation of a non-linear oxidation sequence for formaldehyde via HPS. A comparison of the levels of methanol dehydrogenase and HPS in cells of Bacillus sp. C1 grown on methanol and glucose suggested that the synthesis of these enzymes is not under coordinate control.Abbreviations RuMP ribulose monophosphate - HPS hexulose-6-phosphate synthase - HPI hexulose-6-phosphate isomerase - MDH methanol dehydrogenase - ADH acohol dehydrogenase - PQQ pyrroloquinoline, quinone - DTT dithiothreitol - NBT nitrobluetetrazolium - PMS phenazine methosulphate - DCPIP dichlorophenol indophenol     

Use of an electrostatic sprayer for control of anopheline mosquitoes

The Electrodyn sprayer was compared with a compression sprayer (Hudson X-pert) for residual application of cypermethrin, a pyrethroid insecticide, to control the malaria vectors Anopheles arabiensis Patton and An. funestus Giles in experimental huts at Magugu in Tanzania. The time taken for hut spraying, 2-2.5 min per hut, was similar for both types of sprayer. Two or three huts were treated internally with cypermethrin at 40 or 80 mg a.i./m2 using Electrodyn formulation for comparison with 80 mg a.i./m2 using wettable powder formulation. Each of the twelve huts (including five untreated controls) was fitted with window exit traps and either louvre or verandah traps for mosquito sampling. The Electrodyn sprayer was fitted with a pair of elbowed deflectrodes to direct the positively charged spray droplets onto walls and ceiling. All treatments gave 94-100% mortality-rates of indoor-resting anophelines throughout the evaluation period of 11 weeks post-spray. Reductions of An.arabiensis and An.funestus females by 10-42% and 62-91%, respectively, in rooms and by 72% and 51% in exit traps indicated that cypermethrin deterred mosquitoes from entering the huts. Overall mortality-rates of mosquitoes were 66% of both species in huts treated with 40 mg/m2 Electrodyn, 43% An.funestus and 71% An.arabiensis due to 80 mg/m2 Electrodyn formulation and 49% An.funestus and 64% An.arabiensis due to 80 mg/m2 WP formulation (no significant differences). It is concluded that the Electrodyn sprayer with deflectrodes is a convenient and effective means of residual house-spraying with pyrethroid insecticide for malaria vector control.     

Neuropeptide gene expression and neural activity: Assessing a working hypothesis in nucleus caudalis and dorsal horn neurons expressing preproenkephalin and preprodynorphin

1. The working hypothesis that neuropeptide gene expression in a neuron is an indicator of that neuron's physiological activity is discussed. 2. Representative examples from the literature are presented to support the hypothesis. 3. Further, we discuss the regulation of expression of two opioid peptides, preproenkephalin and preprodynorphin, in laminae I and II of the spinal cord and in nucleus caudalis of the trigeminal nuclear complex, where they may play a role in pain modulation. 4. The expression of the opioid peptide genes can be induced by both painful and nonnoxious stimuli in neurons in time-dependent and sensory-specific fashions.     

Dicarboxylic acid anhydrides as dissociating agents of protein-containing structures

Dissociation of protein-containing structures by modification of protein amino groups with dicarboxylic acid anhydrides is a mild procedure which, in some cases, offers advantages over treatment with alternative dissociating agents, such as urea, guanidine hydrochloride, detergents, high ionic strength, and extremes of pH: In addition to dissociating multimeric proteins and protein aggregates, dicarboxylic acid anhydrides are effective dissociating agents for membrane-bound proteins and nucleoprotein particles. With most dicarboxylic acid anhydrides reviewed, the introduced reagent residues can be eliminated under moderate acid conditions, which allows the purification of unmodified individual components, and the use of disassembly-reconstitution systems valuable for investigating the structural and functional roles played by the individual components of complex particles:Each reagent can be suitable for a particular purpose, depending on the required specificity of the modification and stability of the modified groups: The stability of the acylated amino groups ranges from the very stable succinylated amino groups to the very labile acylation obtained with dimethylmaleic anhydride: Between these extremes, the stability of the modified amino groups decreases stepwise in the following order: maleic, exo-cis-3,6-endoxo-⁴-tetrahydrophthalic, citraconic, and 3,4,5,6-tetrahydrophthalic anhydride. With respect to the selectivity of the produced modification, little or no modification of hydroxyamino acid and cysteine residues has been observed with dimethylmaleic, exo-cis-3,6-endoxo-⁴-tetrahydrophthalic, and 3,4,5,6-tetrahydrophthalic anhydrides: With the other reagents, the extent of modification of hydroxyamino acid residues increases in the order citraconic, maleic and succinic anhydride: Citraconic and maleic anhydrides can produce irreversible modification of cysteine residues, the reactivity of sulfhydryl groups being higher with maleic anhydride:     

Atrophy of compartments of rat lymph nodes related to an entry of lethally altered lymphocytes

Summary This paper reports the occurrence of an accumulation of lethally altered lymphocytes in the subcapsular sinus of a compartment or compartments of some lymph nodes, an unusual feature best developed in nodes of the mesenteric site in aging athymic animals. Many of these cells are rod-like. In other compartments, similar lymphocytes occurred at various depths in the nodal parenchyma. This was accompanied by the disappearance of a compartment's populations of normal lymphoid cells. The observations reveal that lymphocytes, altered in a tissue, may reach the subcapsular sinus of the draining node compartment and migrate into its parenchyma which then undergoes atrophy. The likely involvement of mast cells is discussed.This work was funded by the Medical Research Council of Canada.     

Surface properties of fibrinogen and fibrin

By contact angle measurements on layers of fibrinogen and fibrin, it can be shown that the transformation from fibrinogen to fibrin is accompanied by a change in surface properties from very hydrophilic (fibrinogen) to moderately but definitely hydrophobic (fibrin). It is also shown that, contrary to serum albumin and gamma globulin, fibrinogen does not become more hydrophobic upon drying.     

Analysis of a disease transmission model in a population with varying size

An S I R S epidemiological model with vital dynamics in a population of varying size is discussed. A complete global analysis is given which uses a new result to establish the nonexistence of periodic solutions. Results are discussed in terms of three explicit threshold parameters which respectively govern the increase of the total population, the existence and stability of an endemic proportion equilibrium and the growth of the infective population. These lead to two distinct concepts of disease eradication which involve the total number of infectives and their proportion in the population.Partially supported by NSF Grant No. DMS-8703631. This work was done while this author was visiting the University of VictoriaResearch supported in part by NSERC A-8965     

The selection of microbial communities by constant or fluctuating temperatures

Abstract The diversity of bacterial communities isolated from Antarctic lake sediment in chemostats under constant low temperature (8°C) or diurnally fluctuating temperature (1°C to 16°C) was examined. The median optimum temperature for growth of the freshwater bacteria isolated from the fluctuation chemostat was significantly lower ( P < 1%) than that for those from the constant temperature chemostat. The diversity of the enriched bacterial community isolated in the chemostat culture subjected to short-term temperature fluctuations was greater than that enriched under constant temperature. At least 4 different groups of bacteria, that occupied separate 'temperature niches', were isolated from the fluctuating chemostat compared to only one group isolated from the stable chemostat. Furthermore, a pseudomonad from the fluctuating chemostat was shown to out-compete another pseudomonad from the stable chemostat when both were subjected to the fluctuating temperature regime. However, the pseudomonad of constant (8°C) temperature origin out-competed that isolated under fluctuating conditions when subjected to a stable temperature regime.