Oxidation of NADH by chloramines and chloramides and its activation by iodide and by tertiary amines

Irreversible oxidation of reduced nicotinamide nucleotides by neutrophil-derived halogen oxidants (HOCl, chloramines, HOBr, etc.) is likely to be a highly lethal process, because of the essential role of NAD(P)H in important cell functions such as mitochondrial electron transport, and control of the cellular thiol redox state by NADPH-dependent glutathione reductase. Chloramines (chloramine-T, NH(2)Cl, etc.) and N-chloramides (N-chlorinated cyclopeptides) react with NADH to generate the same products as HOCl, i.e., pyridine chlorohydrins, as judged from characteristic changes in the NADH absorption spectrum. Compared with the fast oxidation of NADH by HOCl, k approximately 3 x 10(5) M(-1) s(-1) at pH 7.2, the oxidation by chloramines is about five orders of magnitude slower; that by chloramides is about four orders of magnitude slower. Apparent rate constants for oxidation of NADH by chloramines increase with increasing proton or buffer concentration, consistent with general acid catalysis, but oxidation by chloramides proceeds with pH-independent kinetics. In presence of iodide the oxidation of NADH by chloramines or chloramides is faster by at least two orders of magnitude; this is due to reaction of iodide with the N-halogen to give HOI/I(2), the most reactive and selective oxidant for NADH among HOX species. Quinuclidine derivatives (QN) like 3-chloroquinuclidine and quinine are capable of catalyzing the irreversible degradation of NADH by HOCl and by chloramines; QN(+)Cl, the chain carrier of the catalytic cycle, is even more reactive toward NADH than HOCl/ClO(-) at physiological pH. Oxidation of NADH by NH(2)Br proceeds by fast, but complex, biphasic kinetics. A compilation of rate constants for interactions of reactive halogen species with various substrates is presented and the concept of selective reactivity of N-halogens is discussed.     

Polarity induced by chloramphenicol and relief by suA

The suA allele, known to relieve polarity in Escherichia coli, also relieves a unique polar effect on E. coli tryptophan operon messenger RNA produced by chloramphenicol.     

Hypobromous acid and bromamine production by neutrophils and modulation by superoxide

MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate to their respective hypohalous acids. We have investigated the generation of HOBr by human neutrophils in the presence of physiological concentrations of chloride and bromide. HOBr was trapped with taurine and detected by monitoring the bromination of 4-HPAA (4-hydroxyphenylacetic acid). With 100 microM bromide and 140 mM chloride, neutrophils generated HOBr and it accounted for approx. 13% of the hypohalous acids they produced. Addition of SOD (superoxide dismutase) doubled the amount of HOBr detected. Therefore we investigated the reaction of superoxide radicals with a range of bromamines and bromamides and found that superoxide radicals stimulated the decomposition of these species, with this occurring in a time- and dose-dependent manner. The protection afforded by SOD against such decay demonstrates that these processes are superoxide-radical-dependent. These data are consistent with neutrophils generating HOBr at sites of infection and inflammation. Both HOBr and bromamines/bromamides have the potential to react with superoxide radicals to form additional radicals that may contribute to inflammatory tissue damage.     

Micronutrient Cation Sorption by Roots and Uptake by Plants

The sorption of ferric iron, copper, zinc and manganese by wheatseedling roots and by discs of cellulose filter paper was measured.The magnitude of sorption at pH 5-0 was Fe(III) > Cu(II)> Zn(II) > Mn(II). Sorption of Cu(II), Zn(II) and Mn(II)increased with increasing pH whilst sorption of Fe(III) decreased.The patterns of sorption are discussed in the light of our knowledgeof the hydrolysis of the metal ions. It is suggested that metalsadsorbed on root surfaces may be remobilized by organic ligandswhich leak from the root cells. Where an external liquid diffusionpath away from the root does not exist, soluble metal ligandcomplexes might accumulate in the water free space and superficialwater film of the root, thus facilitating their uptake intoroot cells and translocation within the plant. Under such conditionsthe amounts of metal translocated to the shoots of wheat seedlingsare shown to be related to the amounts of metal adsorbed bytheir roots. Key words: Adsorption, Micronutrients, Roots     

Diaphragmatic displacement measured by fluoroscopy and derived by Respitrace

In eight healthy volunteers we simultaneously measured the axial diaphragmatic motion by fluoroscopy and the cross-sectional area changes of the rib cage (RC) and abdomen (ABD) by Respitrace (RIP) during semistatic vital capacities (VC). We found that, if the fluoroscopic axial displacement of the posterior part of the diaphragm between residual volume (RV) and total lung capacity (TLC) is considered equal to 100%, the movement of the middle part is 90%, whereas that of the anterior part is only approximately 60%; the ratio of the axial displacements to mouth volume, furthermore, decreases at high lung volumes, especially for the anterior part. The RIP signal is nearly linearly related to mouth volume, but the contribution of the RC (delta RC) progressively increases (and is approximately 80% RIP at TLC), whereas the volume contribution of the ABD (delta ABD) levels off (to 20% RIP at TLC). The diaphragmatic volume displacement calculated from the theoretical analysis described by Mead and Loring also levels off at high volumes similarly as the ABD but is approximately 50% RIP at TLC. Finally, the axial movements of the three parts of the diaphragm are linearly related to the RC and ABD cross-sectional-area changes (r 0.91-0.97) and are even significantly better correlated with the "calculated" diaphragmatic volume displacement.     

Plaque Formation by Mumps Virus and Inhibition by Antiserum

Boston and ABC strains of mumps virus produced plaques approximately 1.0 mm in diameter in monolayers of BGM cells. The plaques were circular and either clear or target-like in form. Ricki strain virus produced plaques of similar size and form but, in addition, a red plaque was observed with this agent. The vaccine strain of mumps virus, Jeryl Lynn, produced minute clear plaques approximately 0.3 mm in diameter. Incorporation of diethylaminoethyl (DEAE)-dextran into the overlay medium did not affect the size difference between Jeryl Lynn plaques and those of the other strains. However plaques of the Jeryl Lynn and Ricki strains were more easily visualized when the overlay medium contained 400 mug/ml of DEAE-dextran. Simultaneous titration by plaque formation and roller tube infectivity showed that these two methods were of equal sensitivity. Virus neutralization by antibody was demonstrated by plaque reduction. Rise in antibody titer was observed in sera from human and animal infection, human vaccination, and rabbit immunization.     

Sampling for aphids by traps and by crop inspection

The catches of thirty aphid genera and species during 3 years in a suction trap at 40 ft and on a yellow cylindrical sticky trap at 5 ft at Rothamsted and Broom's Barn are tabulated. Suction-trap catches were the more consistent but both were more effective at recording the first seasonal immigration of Myzuspersicae (Sulz.) and Aphis fabae Scop, than the British Sugar Corporation crop-inspection scheme. The catches show the differential attraction to yellow by different species, the effects of local vegetation, and the seasonal distribution of aphids that are crop pests or potential vectors of viruses.     

Pea seedling growth and development regulated by cotyledons and modified by irradiance

Growth and development of hydroponically grown pea seedlings ( Pisum sativum L. cv. Alaska) were measured using stem and root length as well as number of leaves and lateral roots. The growth was dependent on the presence of cotyledons and was modulated by the irradiance. All plants were grown in a full nutrient solution. If grown at low irradiance (73 μmol m^-2s^-1) they depended more and for a longer time on the cotyledons than plants grown at high irradiance (220 μmol m^-2s^-1). Low irradiance caused stem elongation but decreased root length and number of lateral roots as compared to plants grown at high irradiance. The dark respiration of the leaves was measured as oxygen uptake. In plants grown at the low irradiance, excision of the cotyledons caused the rate of oxygen uptake to increase by a factor of three, and the increase was sensitive to cyanide. Decotyledonized plants showed a high respiration rate and a diminished leaf growth for their entire life cycle. CO₂ fixation also increased in decotyledonized pea seedlings grown at either irradiance. The mobilization of food reserves from the seeds was positively correlated to seed dry weight, but only if the plants were grown at 73 μmol m^-2s^-1. Increasing dry weight of the seed enhanced top growth, whereas root growth was depressed, so that top and root responds differently with regard to that part of growth which depends on mobilization of reserves from the seed.     

Nitric oxide production by Leishmania-infected macrophages and modulation by cytokines and prostaglandins

Nitric oxide (NO) produced by an inducible nitric oxide synthase (iNOS or NOS2) plays a major microbicidal role in murine macrophages and its importance is now emerging also in the dog and human models. In dogs we demonstrated that macrophages in vitro infected with Leishmania infantum produced NO, after stimulation with cytokine-enriched peripheral blood mononuclear cell supernatants. In addition, parasite killing was reduced by the NOS inhibitor L-NG monomethylarginine. On the contrary, canine blood monocytes before macrophage differentiation did not release NO, and their leishmanicidal activity was instead correlated with superoxide anion and interferon (IFN)-gamma production. In human macrophage cultures, after infection with Leishmania infantum, we showed both iNOS expression by immunofluorescence and western blotting and NO release by the Griess reaction for nitrites. Various cytokines and prostaglandins can differently modulate NO synthesis. In our experiments, stimulation by recombinant human IFN-gamma and bacterial lipopolysaccharide greatly enhanced iNOS expression and NO production in human macrophages. In addition, the prostaglandin E2 increased NO release in activated, Leishmania-infected human macrophages. These results are interesting in the light of a possible immunological or pharmacological regulation of NO synthesis and microbicidal functions of macrophages.     

Peptide binding by calmodulin and its proteolytic fragments and by troponin C

Calmodulin and troponin C exhibit calcium-dependent binding of 1 mol/mol of dynorphin. The dissociation constants of the complexes, determined in 0.20 N KC1-1.0 mM CaCI2, pH 7.3, are 0.6 microM for calmodulin, 2.4 microM for rabbit fast skeletal muscle troponin C, and 9 microM for bovine heart troponin C. Experiments with deletion peptides of dynorphin show that peptide chain length and especially charge affect the binding of the peptides by calmodulin. Dynorphin, but not mastoparan or melittin, inhibits adenosinetriphosphatase activity in a reconstituted rabbit skeletal muscle actomyosin assay. The inhibition is partially reversed by the addition of calmodulin or troponin C in the presence of calcium. Calmodulin also exhibits calcium-dependent binding of a synthetic peptide corresponding to positions 104-115 of rabbit fast skeletal muscle troponin I. Mastoparan is a tetradecapeptide from the vespid wasp having exceptional affinity for calmodulin, with Kd approximately 0.3 nM [Malencik, D.A., & Anderson, S.R. (1983) Biochem. Biophys. Res. Commun. 114, 50]. The addition of 1 mol/mol of mastoparan to the complex of calmodulin with dynorphin results in complete dissociation of dynorphin. Similar titrations of the skeletal muscle troponin C-dynorphin complex produce a gradual dissociation consistent with a dissociation constant of 0.2 microM for the troponin C-mastoparan complex. Fluorescence anisotropy measurements using the intrinsic tryptophan fluorescence of mastoparan X show strongly calcium-dependent binding by proteolytic fragments of calmodulin. binding by proteolytic fragments of calmodulin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Thermal and metabolic responses to cold by men and by eumenorrheic and amenorrheic women

Previous work has suggested that men (M) are more sensitive to cold stress than women. There have also been observations that suggest that amenorrheic women (AW) are less thermally responsive than eumenorrheic women (EW). We investigated the hypothesis that M, EW, and AW would have different responses to cold stress. The subjects (6/group) were tested four times: twice at rest for 60 min (5 and 22 degrees C) and twice in a progressive exercise test (5 and 22 degrees C). At rest at 22 degrees C AW had a lower O2 uptake (VO2) than M and lower rectal (Tre) and finger temperatures than EW. At rest at 5 degrees C both AW and EW had lower skin temperature (Tsk) than M, but there were no group differences in peripheral Tsk sites. M increased VO2 after 10 min and EW after 20 min of cold stress; however, AW did not increase metabolism until 60 min. In the two exercise tests Tre increased in proportion to relative work load; in the 5 degrees C test there was little evidence that exercise increased Tsk sites above rest levels. Few of the metabolic or thermal differences could be accounted for by body fatness, body surface area (BSA), or BSA/kg. The data support the hypothesis that M, EW, and AW have different responses to cold stress.