The persistent microbicidal effect in water exposed to the corona discharge

This article describes and particularly explains a new phenomenon of persistent microbicidal effect of water previously exposed to the low-temperature plasma, which cannot be attributed to the acidification only. The direct microbicidal action of plasma is well documented, being mediated by number of reactive particles with a short lifetime. However, we observed the microbicidal effect also in exposed water stored for a month, where it must be mediated by stable particles. In water and in phosphate-buffered saline, the formation of NO_x and corresponding acids, H₂O₂ and O₃ was confirmed after exposition to the low-temperature plasma generated in air by DC negative glow corona and positive streamer discharge. The time course of acidification, H₂O₂ and O₃ formation were deremined. Except uncertain traces of HCN, SIFT-MS analysis of exposed liquids reveals no additional reactive compounds. The microbicidal effect persists almost unchanged during 4 weeks of storage, although O₃ completely and H₂O₂ almost disappears. Staphylococcus epidermidis and Escherichia coli were inactivated within 10 min of incubation in exposed liquids, Candida albicans needs at least 1 h. The solutions prepared by artificial mixing of reactive compounds mimic the action of exposed water, but in lesser extent. The acid milieu is the main cause of the microbicidal effect, but the possibility of still unidentified additional compound remains open.     

Production of Photons in the Bactericidal Effect of Transient Electric Arcs in Aqueous Systems

The radiation in the visible and ultraviolet regions from submerged, transient electrical arcs was measured with a K(3)Fe(C(2)O(4))(3) chemical actinometer and was compared to the bactericidal effect obtained with the same electrical arrangements. Photon production and bactericidal effect were obtained at lower voltages with a smaller electrode separation than with a wider one. At higher voltages, both increased with wider electrode separations. The voltages at maximal photon production efficiency coincided with those of maximal bactericidal efficiency. However, the same photon radiation produced by different electrical arrangements did not always yield the same bactericidal effect in the small discharge vessel usually employed. In a larger discharge vessel, the bactericidal effect was closely correlated with the photon production. The efficiency of photon production by transient arcs was smaller than that of germicidal mercury lamps, particularly with respect to wavelengths of great bactericidal activity. The mechanisms of inactivation and their use for practical disinfection purposes are discussed.     

Calcitonin gene-related peptide 8-37 inhibits the evoked discharge frequency of wide dynamic range neurons in dorsal horn of the spinal cord in rats.

The present study was performed to explore the effect of calcitonin gene-related peptide 8-37 (CGRP8-37) on the electrical stimulation-evoked discharge frequency of wide dynamic range (WDR) neurons in the dorsal horn of the spinal cord in rats. The discharge frequencies of WDR neurons were evoked by transdermic electrical stimulation applied on the ipsilateral hindpaw. CGRP8-37 was applied directly on the dorsal surface of the L3 to L5 spinal cord. After the administration of 3 nmol of CGRP8-37, the evoked discharge frequency of WDR neurons decreased significantly, an effect lasting more than 30 min. The results indicate that CGRP receptors play an important role in the transmission of presumed nociceptive information in the dorsal horn of the spinal cord.     

Macrophage activation for microbicidal activity against Leishmania major: inhibition of lymphokine activation by phosphatidylcholine-phosphatidylserine liposomes

Resident peritoneal macrophages from untreated mice develop microbicidal activity against amastigotes of the protozoan parasite Leishmania tropica (current nomenclature = Leishmania major) after in vitro exposure to LK from antigen-stimulated leukocyte culture fluids. This LK-induced macrophage microbicidal activity was completely abrogated by addition of 7:3 phosphatidylcholine: phosphatidylserine liposomes. Liposome inhibition was not due to direct toxic effects against the parasite or macrophage effector cell; factors in LK that induce macrophage microbicidal activity were not adsorbed or destroyed by liposome treatment. Other phagocytic particles, such as latex beads, had no effect on microbicidal activity. Moreover, liposome inhibition of activated macrophage effector function was relatively selective: LK-induced macrophage tumoricidal activity was not affected by liposome treatment. Liposome inhibition was dependent upon liposome dose (5 nmoles/culture) and time of addition of leishmania-infected, LK-treated macrophage cultures. Addition of liposomes through the initial 8 hr of culture completely inhibited LK-induced macrophage microbicidal activity; liposomes added after 16 hr had no effect. Similarly, microbicidal activity by macrophages activated in vivo by BCG or Corynebacterium parvum was not affected by liposome treatment. Liposome treatment also did not affect the increased resistance to infection induced in macrophages by LK. These data suggest that liposomes interfere with one or more early events in the induction of activated macrophages (macrophage-LK interaction) and not with the cytotoxic mechanism itself (parasite-macrophage interaction). These studies add to the growing body of data that implicate cell lipid in regulatory events controlling macrophage effector function.     

Effect of a DC external electric field on the properties of a nonuniform microwave discharge in hydrogen at reduced pressures

The effect of a dc external electrical field on the properties of a highly nonuniform electrode microwave discharge in hydrogen at a pressure of 1 Torr was studied using optical emission spectroscopy and selfconsistent two-dimensional simulations. It is shown that the negative voltage applied to the antenna electrode with respect to the grounded chamber increases the discharge radiation intensity, while the positive voltage does not affect the discharge properties. The simulation results agree well with the experimental data.     

The effect of galanin on wide-dynamic range neuron activity in the spinal dorsal horn of rats

The present study investigated the effect of galanin on wide-dynamic range (WDR) neuron activity in the dorsal horn of the spinal cord of rats. The evoked discharge of WDR neurons was elicited by transdermic electrical stimulation applied on the ipsilateral hindpaw of rats. Galanin was administered directly on the spinal dorsal surface of L3-L5. The evoked discharge frequency of the WDR neurons decreased significantly after the administration of galanin and the effect lasted for more than 30 min. Furthermore, the inhibitory effect of galanin on the evoked discharge frequency of WDR neurons was blocked by following administration of the galanin antagonist galantide, indicating that the inhibitory effect of galanin on the activity of WDR neurons was induced by activating galanin receptors in the dorsal horn of the spinal cord. The results suggest that galanin has an inhibitory role in the transmission of presumed nociceptive information in the dorsal horn of the spinal cord in rats.     

Role of calcitonin gene-related peptide and its antagonist on the evoked discharge frequency of wide dynamic range neurons in the dorsal horn of the spinal cord in rats.

The present study was performed to explore the effect of calcitonin gene-related peptide (CGRP) and its antagonist CGRP8-37 on the evoked discharge frequency of wide dynamic range (WDR) neurons in the dorsal horn of the spinal cord in rats. Recording was performed with a multibarrelled glass micropipette and the chemicals were delivered by iontophoresis. The discharge of WDR neurons was evoked by transdermic electrical stimulation applied on the ipsilateral hindpaw. (1) Iontophoretic application of CGRP at an ejection current of 100 nA increased the discharge frequency of WDR neurons significantly. (2) Iontophoretic application of CGRP8-37 at an ejection current of 80 or 160 nA induced significant decreases in the discharge frequency of WDR neurons, but not at 40 nA. (3) Iontophoretic application of CGRP8-37 not only antagonized the CGRP-induced increase in the evoked discharge frequency of WDR neurons but also induced a significant decrease in the evoked discharge frequency of WDR neurons compared to basal levels. The results indicate that CGRP and its receptors play a facilitary role on the transmission and/or modulation of nociceptive information in the dorsal horn of the spinal cord in rats.     

剌激兔面神经核背内侧区对孤束核腹外侧亚核呼吸相关神元的影响

In urethane-anesthetized, vagotomized and paralyzed rabbits, effects of electrical stimulation of the dorso-medial area of the nucleus facialis (DMNF) on the respiration-related units (RRUs) in ventro-lateral region of nucleus tractus solitaris (VLNTS) were observed. The experimental results showed that during electrical stimulation of DMNF the majority of the inspiratory (I) neurons (64.4%) were increased in frequency and duration of discharge, some to a marked extent. During electrical stimulation of DMNF the expiratory neurons (35%) were decreased in their frequency and duration of discharge, some to a marked extent too. The responses of RRUs in ipsilateral and contralateral VLNTS to stimulation of DMNF was not statistically significant (P greater than 0.05). It is suggested that DMNF may have a facilitating effect on the inspiratory neurons and an inhibiting effect on the expiratory neurons in VLNTS.     

Characteristics of a corona discharge with a hot corona electrode

The effect of the temperature of the corona electrode on the electrical characteristics of a corona discharge was studied experimentally. A modified Townsend formula for the current-voltage characteristic of a one-dimensional corona is proposed. Gasdynamic and thermal characteristics of a positive corona discharge in a coaxial electrode system are calculated. The calculated results are compared with the experimental data.     

Effect of the Water and Barrier Submersion Depths on the Characteristics of a High-Voltage Discharge Propagating over a Water Surface

This work continues the series of studies of pulsed high-voltage discharges propagating over liquid surfaces in the presence of barriers. In this work, the influence of the barrier position relative to the air electrode on the discharge voltage in the stage of the completed discharge is analyzed. The effect of the water depth and barrier submersion depth on the propagation of a pulsed discharge is studied.     

On the relation between expiratory duration and subsequent inspiratory duration

To characterize respiratory interphase relationships in dogs, inspiratory duration (TI) or expiratory duration (TE) was systematically altered by electrical activation of vagal afferents, and the effect on subsequent TE or TI values was measured from the phrenic discharge. A linear TI-subsequent TE relationship was found. Following a vagally mediated prolongation of TE, 1) TI was prolonged, and the TE-subsequent TI relationship was curvilinear, 2) the threshold for inspiratory termination by phasic vagal inputs was increased, 3) the amplitude of the time course of the phrenic discharge was reduced so that the peak discharge reached the same level at inspiratory termination independent of TI, 4) the effect on TI prolongation persisted for several breaths whereas the effect was minimal on subsequent TE values, and 5) for tonic inputs the direct shortening of TI was nearly offset by the indirect lengthening of TI. These studies suggest the existence of slow central mechanisms that provide adaptation to elevated levels of vagal input in the control of TI. These mechanisms may also be responsible for the interphase timing relationships.     

Effect of Electrode Polarity on the Development of the Breakdown in Conductive Water with Air Microbubbles

Plasma Physics Reports - The effect of electrode polarity in the pin-to-rod geometry on the development of pulsed electric discharge in water with specific electrical conductivity of (90 ± 10)...     

The effects of neomycin on membrane properties and discharge activity of an isolated sensory neuron

The effects of neomycin sulfate were examined upon the discharge activity and electrical membrane properties of an isolated invertebrate sensory neuron, the crayfish stretch receptor neuron. Neomycin depressed cell discharge activity in a concentration-dependent manner over the concentration range of 0.01-1.0 mM. Significant concentration-related increases were observed in the resting membrane potential and the width of the orthodromic action potential. There was a significant concentration-dependent decrease in the fast rising phase of the antidromic action potential. Significant changes also were observed in other electrical properties such as membrane resistance, but these were found not to be concentration related. The most significant change was membrane hyperpolarization, which could account for the depression of cell discharge activity. The observed changes are consistent with a neomycin-induced change in the membrane potassium conductance. It is proposed that the neural effect of neomycin is a selective interaction with the neuronal membrane phospholipids.     

Spark channel propagation in a microbubble liquid

Experimental study on the development of the spark channel from the anode needle under pulsed electrical breakdown of isopropyl alcohol solution in water with air microbubbles has been performed. The presence of the microbubbles increases the velocity of the spark channel propagation and increases the current in the discharge gap circuit. The observed rate of spark channel propagation in microbubble liquid ranges from 4 to 12 m/s, indicating the thermal mechanism of the spark channel development in a microbubble liquid.     

Influence of an electrical potential on the charge transfer kinetics of bacteriorhodopsin

The adsorption of bacteriorhodopsin(bR)-containing purple membranes (PM) to black lipid membranes (BLM) was used to study the charge translocation kinetics of bR upon flash excitation.

The discharge of the PM-BLM system after charging upon illumination is found to proceed quite slowly (discharge time up to several minutes) but is considerably accelerated by addition of the protonophore FCCP.

Therefore, the dependence of the proton transfer kinetics in bR on electrical potentials generated by preceding flashes of varying repetition rate and intensity was investigated. The kinetics are slowed down with increasing flash intensity as well as repetition rate. This effect is partly abolished by small amounts of FCCP.

A new model is introduced which takes into account the instantaneous feedback of the electrical potential on the kinetics of the pump current. It explains the observed deviations from first-order kinetics and renders an approach with “distributed kinetics” unnecessary.

     

In vitro leishmanicidal activity of a monoclonal antibody mimicking a yeast killer toxin

The microbicidal effect of a monoclonal antiidiotypic antibody, mimicking the activity of a yeast killer toxin, characterized by a wide antimicrobial spectrum, has been evaluated in vitro against two relevant species of protozoan parasites, Leishmania major and Leishmania infantum. The antiidiotypic antibody exerted a significant and dose-dependent antileishmanial activity against parasite promastigotes in comparison to an irrelevant isotype-matched monoclonal antibody. This is the first demonstration that an antibody, which had been already shown to be fungicidal and bactericidal, may also exert a direct microbicidal activity against protozoa.     

大鼠心率变异性频谱中高频成分的中枢机理分析

本文探讨心率变异性（ＨＲＶ）频谱中高频成分的中枢机理。对正常ＳＤ大量给予不同频率的人工通气并电刺激延髓疑核,观察ＨＲＶ频谱的改变,记录与呼吸节律同步的延髓头端腹外侧区（ｒＶＬＭ）及其周围区神经元细胞外单位放电,对ＨＲＶ和放电变异性进行相干函数分析。结果显示：（１）ＨＲＶ的高频成分的中心频率随着人工通气频率的增加而增加,呈高度线性相关,（ｒ＝０．８３,Ｐ〈０．０００１）;（２）对ｒＶＬＭ及其周围区与     

生长素对胃运动和对海马胃肠敏感神经元放电活动的影响

目的:探讨海马ghrelin对GD敏感神经元放电和弓状核ghrelin对胃运动的影响。方法:在细胞外记录海马的放电情况,并且检测清醒大鼠的胃运动。通过PCR免疫印迹和免疫荧光组织化学染色等方法来测定GHSR-1a在海马中的表达。用逆行追踪和免疫荧光组织化学染色检测ghrelin神经元的投射情况。Ghrelin况荧光金双标记的神经元以及GHSR-1a的表达分别可以在ARC和海马中观察到。结果:Ghrelin或者ARC电刺激可以兴奋海马区的胃牵张敏感神经元。Ghrelin受体拮抗剂[d-Lys-3]-GHRP-6预处理可以完全或者部分阻断这种兴奋作用。海马注射ghrelin可以显著促进胃运动,并且呈现剂量依赖关系,而且这种作用可以被[d-Lys-3]-GHRP-6所阻断。电刺激ARC能够促进胃运动。然而,预处理时[d-Lys-3]-GHRP-6可以减弱这些作用。电损毁海马可以减弱胃运动的兴奋作用,这个作用通过电刺激ARC产生的。结论:通过海马促进胃运动中ghrelin起着重要的作用。ARC可能参与调节海马对胃动力的影响。     

Reaction of microorganisms to the digestive fluid of the earthworms

The reaction of soil bacteria and fungi to the digestive fluid of the earthworm Aporrectodea caliginosa was studied. The fluid was obtained by centrifugation of the native enzymes of the digestive tract. The inhibition of growth of certain bacteria, spores, and fungal hyphae under the effect of extracts from the anterior and middle sections of the digestive tract of A. caliginosa was discovered for the first time. In bacteria, microcolony formation was inhibited as early as 20-30 s after the application of the gut extracts, which may indicate the nonenzymatic nature of the effect. The digestive fluid exhibited the same microbicidal activity whether the earthworms were feeding on soil or sterile sand. This indicates that the microbicidal agents are formed within the earthworm's body, rather than by soil microorganisms. The effect of the digestive fluid from the anterior and middle divisions is selective in relation to different microorganisms. Of 42 strains of soil bacteria, seven were susceptible to the microbicidal action of the fluid (Alcaligenes.faecalis 345-1, Microbacterium sp. 423-1, Arthrobacter sp. 430-1, Bacillus megaterium 401-1, B. megaterium 413-1, Kluyvera ascorbata 301-1, Pseudomonas reactans 387-2). The remaining bacteria did not die in the digestive fluid. Of 13 micromycetes, the digestive fluid inhibited spore germination in Aspergillus terreus and Paecilomyces lilacinus and the growth of hyphae in Trichoderma harzianum and Penicillium decumbens. The digestive fluid stimulated spore germination in Alternaria alternata and the growth of hyphae in Penicillium chrysogenum. The reaction of the remaining micromycetes was neutral. The gut fluid from the posterior division of the abdominal tract did not possess microbicidal activity. No relation was found between the reaction of microorganisms to the effects of the digestive fluid and the taxonomic position of the microorganisms. The effects revealed are similar to those shown earlier for millipedes and wood lice in the following parameters: quick action of the digestive fluid on microorganisms, and the selectivity of the action on microorganisms revealed at the strain level. The selective effect of the digestive gut fluid of the earthworms on soil microorganisms is important for animal feeding, maintaining the homeostasis of the gut microbial community, and the formation of microbial communities in soils.     

Synthesis of benzenepropanamine analogues as non-detergent spermicides with antitrichomonas and anticandida activities

Fifteen analogues of benzenepropanamine were synthesized and evaluated for their spermicidal as well as microbicidal activities against Trichomonas vaginalis and Candida spp. Several compounds showed appreciable dual activities. Compound 12 exhibited good spermicidal (MEC=0.1%) along with substantial anticandidal (MIC=0.05%) activities, while compounds 3 and 6 showed significant microbicidal activities with moderate spermicidal effect. The SAR of these structures is being discussed here in this communication. It is concluded that suitable structural modifications in this class of compounds at 3-amino position may lead to a potent spermicide with associated microbicidal activity.