Localization of vanadium-containing particles in the lungs of uranium/vanadium miners

Several geological formations of the Utah-Colorado mining region mined for uranium ore during and after World War II had been mined earlier for vanadium. Therefore, most miners and millers from that region were exposed to those metals’ ores or tailings at one time or another. Preliminary investigation to determine uranium and vanadium retained in the lungs of a former uranium miner and miller from this region, who died of lung cancer (mesothelioma), showed a high nonuniform distribution of vanadium. This observation led to the hypothesis that the vanadium content in the lungs could be associated with inhaled particles. Further examination of spectra of characteristic X-rays obtained by scanning particle-induced X-ray emission (microPIXE) of an autopsy sample of this lung indicated that vanadium was indeed present in localized sites within the 20-μm spatial resolution of the proton beam. This work points out that the microPIXE-RBS (Rutherford backscattering) test for vanadium can be used for site localization of inhaled particles retained in the lungs. Further studies are in progress to: (i) locate uranium-bearing particles in lung tissues of former uranium miners and millers; and (ii) evaluate the local doses of alpha radiation received from these particles.     

Thorotrast uptake and transit in embryonic glia, heart fibroblasts and neurons in vitro

Thorotrast (colloidal ThO₂) is incorporated into coated vesicles, various agranular vesicles and sacs, and a surface-associated system of membranous channels in times as short as 1 min by single cultured glial and heart cells. Thorotrast appears in ‘C’-shaped bodies and in small, dense bodies of the lysosomal series within ca. 25 min. With longer chase periods, thorotrast ‘clears’ from all cytoplasmic organelles except the lysosomal series. The technique of applying thorotrast and using varying chase periods fails to distinguish a class of membranous organelles, located close to the cell periphery, that might serve as a source of new cell surface during locomotory activity. Similarly, thorotrast (colloidal ThO₂) is incorporated into almost all classes of membrane-bounded organelles of growth cones and axons of single nerve cells in vitro in times as short as 1 min. This includes elements of the smooth endoplasmic reticulum. No thorotrast enters the lysosomal granules in this short time. During various chase periods, the tracer disappears from the initial sites of incorporation and accumulates in dense bodies of the lysosome series within growth cones and axons. ‘C’-shaped bodies may be an intermediate in that process. No unique sites of endocytotic activity or of a complete absence of endocytosis were observed that could be correlated with growth cone function and axonal elongation, though the presence of the tracer in agranular sacs of the smooth endoplasmic reticulum in growth cones could reflect hypothesized cycling of cell surface (Bray, 1973).     

Measurement of hydrocarbon-degrading microbial populations by a 96-well plate most-probable-number procedure

A 96-well microtiter plate most-probable-number (MPN) procedure was developed to enumerate hydrocarbondegrading microorganisms. The performance of this method, which uses number 2 fuel oil (F2) as the selective growth substrate and reduction of iodonitrotetrazolium violet (INT) to detect positive wells, was evaluated by comparison with an established 24-well microtiter plate MPN procedure (the Sheen Screen), which uses weathered North Slope crude oil as the selective substrate and detects positive wells by emulsification or dispersion of the oil. Both procedures gave similar estimates of the hydrocarbon-degrader population densities in several oil-degrading enrichment cultures and sand samples from a variety of coastal sites. Although several oils were effective substrates for the 96-well procedure, the combination of F2 with INT was best, because the color change associated with INT reduction was more easily detected in the small wells than was disruption of the crude oil slick. The method's accuracy was evaluated by comparing hydrocarbon-degrader MPNs with heterotrophic plate counts for several pure and mixed cultures. For some organisms, it seems likely that a single cell cannot initiate sufficient growth to produce a positive result. Thus, this and other hydrocarbon-degrader MPN procedures might underestimate the hydrocarbon-degrading population, even for culturable organisms.     

Evaluation of a model for the effects of substrate interactions on the kinetics of reductive dehalogenation

The effects of primary electron-donor and electron-acceptor substrates on the kinetics of TCA biodegradation in sulfate-reducing and methanogenic biofilm reactors are presented. Of the common anaerobic electron-donor substrates that were tested, only formate stimulated the TCA biodegradation rate in both reactors. In the sulfate-reducing reactor, glucose also stimulated the reaction rate. The effects of formate and sulfate on TCA biodegradation kinetics were analyzed using a model for primary substrate effects on reductive dehalogenation. Although some differences between the model and the data are evident, the observed responses of the TCA degradation rate to formate and sulfate were consistent with the model. Formate stimulated the TCA degradation rate in both reactors over the entire range of TCA concentrations that were studied (from 50 g TCA/L to 100 mg TCA/L). The largest effects occurred at high TCA concentrations, where the dehalogenation kinetics were zero order. Sulfate inhibited the first-order TCA degradation rate in the sulfate-reducing reactor, but not in the methanogenic reactor. Molybdate, which is a selective inhibitor of sulfate reduction, stimulated the TCA removal rate in the sulfate-reducing reactor, but had no effect in the methanogenic reactor.     

A model for the effects of primary substrates on the kinetics of reductive dehalogenation

A kinetic model that describes substrate interactions during reductive dehalogenation reactions is developed. This model describes how the concentrations of primary electron-donor and -acceptor substrates affect the rates of reductive dehalogenation reactions. A basic model, which considers only exogenous electron-donor and -acceptor substrates, illustrates the fundamental interactions that affect reductive dehalogenation reaction kinetics. Because this basic model cannot accurately describe important phenomena, such as reductive dehalogenation that occurs in the absence of exogenous electron donors, it is expanded to include an endogenous electron donor and additional electron acceptor reactions. This general model more accurately reflects the behavior that has been observed for reductive dehalogenation reactions. Under most conditions, primary electron-donor substrates stimulate the reductive dehalogenation rate, while primary electron acceptors reduce the reaction rate. The effects of primary substrates are incorporated into the kinetic parameters for a Monod-like rate expression. The apparent maximum rate of reductive dehalogenation (q _{m, ap} ) and the apparent half-saturation concentration (K _ap ) increase as the electron donor concentration increases. The electron-acceptor concentration does not affect q _{m, ap} , but K _ap is directly proportional to its concentration.Definitions for model parameters RX halogenated aliphatic substrate - E-M ⁿ reduced dehalogenase - E-M ⁿ⁺² oxidized dehalogenase - [E-M ⁿ ] steady-state concentration of the reduced dehalogenase (moles of reduced dehalogenase per unit volume) - [E-M ⁿ⁺²] steady-state concentration of the oxidized dehalogenase (moles of reduced dehalogenase per unit volume) - DH₂ primary exogenous electron-donor substrate - A primary exogenous electron-acceptor substrate - A2 second primary exogenous electron-acceptor substrate - X biomass concentration (biomass per unit volume) - f fraction of biomass that is comprised of the dehalogenase (moles of dehalogenase per unit biomass) - stoichiometric coefficient for the reductive dehalogenation reaction (moles of dehalogenase oxidized per mole of halogenated substrate reduced) - stoichiometric coefficient for oxidation of the primary electron donor (moles of dehalogenase reduced per mole of donor oxidized) - stoichiometric coefficient for oxidation of the endogenous electron donor (moles of dehalogenase reduced per unit biomass oxidized) - stoichiometric coefficient for reduction of the primary electron acceptor (moles of dehalogenase oxidized per mole of acceptor reduced) - stoichiometric coefficient for reduction of the second electron acceptor (moles of dehalogenase oxidized per mole of acceptor reduced) - r _RX rate of the reductive dehalogenation reaction (moles of halogenated substrate reduced per unit volume per unit time) - r _d1 rate of oxidation of the primary exogenous electron donor (moles of donor oxidized per unit volume per unit time) - r _d2 rate of oxidation of the endogenous electron donor (biomass oxidized per unit volume per unit time) - r _a1 rate of reduction of the primary exogenous electron acceptor (moles of acceptor reduced per unit volume per unit time) - r _a2 rate of reduction of the second primary electron acceptor (moles of acceptor reduced per unit volume per unit time) - k _RX mixed second-order rate coefficient for the reductive dehalogenation reaction (volume per mole dehalogenase per unit time) - k _d1 mixed-second-order rate coefficient for oxidation of the primary electron donor (volume per mole dehalogenase per unit time) - k _d2 mixed-second-order rate coefficient for oxidation of the endogenous electron donor (volume per mole dehalogenase per unit time) - b first-order biomass decay coefficient (biomass oxidized per unit biomass per unit time) - k _a1 mixed-second-order rate coefficient for reduction of the primary electron acceptor (volume per mole dehalogenase per unit time) - k _a2 mixed-second-order rate coefficient for reduction of the second primary electron acceptor (volume per mole dehalogenase per unit time) - q _m,ap apparent maximum specific rate of reductive dehalogenation (moles of RX per unit biomass per unit time) - K _ap apparent half-saturation concentration for the halogenated aliphatic substrate (moles of RX per unit volume) - k _ap apparent pseudo-first-order rate coefficient for reductive dehalogenation (volume per unit biomass per unit time)     

Appearance of high-molecular-weight acetylcholinesterase in aneural muscle developing in vivo

Acetylcholinesterase was studied in the superior oblique muscle of the duck embryo during the course of in vivo development. Normally developing, paralyzed, and uninnervated muscles were studied using velocity sedimentation for separation of various forms and biochemical determination of enzyme activity, and light and electron microscopy for histochemical and cytochemical localization of enzyme. Results indicate that neither muscle activity nor contact by the motor neurons is essential for the appearance of high-molecular-weight form of acetylcholinesterase on muscle cells developing in vivo. Acetylcholinesterase activity per muscle was considerably lower in the paralyzed and aneural muscles than the normal muscle. The absolute loss of acetylcholinesterase parallels loss of muscle protein in paralyzed and aneural muscles and may be secondary. Paralysis or absence of innervation had no significant effect on the specific activity of acetylcholinesterase.     

中国西北沙漠夜间活动的东鳖甲属昆虫二新种(鞘翅目:拟步甲科:漠甲亚科)

记述中国西北地区东鳖甲属2新种:巴丹东鳖甲A.badainica Ba,Ren&Liu sp.nov.和古尔班东鳖甲A.gurbantunggutica Ba&Ren sp.nov.,提供了主要鉴别特征和形态图,并简要讨论了其昼夜活动规律.