One-hour Exposure Research Articles

A Novel Combined Approach of Short-Chain Sphingolipids and Thermosensitive Liposomes for Improved Drug Delivery to Tumor Cells.

Despite the advantages of liposomal drug delivery, the bioavailability of the chemotherapeutic drugs to tumor cells is limited by their slow release from nanocarriers and low drug permeability across cell membranes. Drug encapsulation into stealth thermosensitive liposomes can improve drug delivery to tumors by combining efficient accumulation at tumors and the active release of the payload following remote heat triggering. Short-chain sphingolipids are known to enhance cellular uptake of amphiphilic drugs. We hypothesized that short-chain sphingolipids could be utilized to further improve intracellular drug delivery from a thermoresponsive formulation by enhancing the cell membrane passage of released drug. The following two strategies were investigated: (1) co-delivery of C8-glucosylceramide and doxorubicin within the thermosensitive liposomes and (2) pretreatment with glucosylceramide-enriched drug-free liposomes and subsequent treatment with doxorubicin loaded thermosensitive liposomes. Liposomes were prepared and extensively characterized. Drug uptake, cell cytotoxicity and live cell imaging were performed under normothermic and hyperthermic conditions in melanoma cells. In these studies, hyperthermia improved drug delivery from doxorubicin loaded thermosensitive formulations. However, the results from cell experiments indicated that there was no additional benefit in the co-delivery strategy using doxorubicin loaded glucosylceramide-enriched thermosensitive liposomes. In contrast, cellular studies showed significantly higher doxorubicin internalization in the pretreatment strategy. One-hour exposure of the cells to C8-glucosylceramide before applying hyperthermia caused improved doxorubicin uptake and cytotoxicity as well as an almost instantaneous cellular entry of the doxorubicin released from thermosensitive liposomes. This novel, two-step drug delivery approach can be potentially beneficial for the intracellular delivery of cell impermeable chemotherapeutics.

The immediate effects of acoustic trauma on excitation and inhibition in the inferior colliculus: A Wiener-kernel analysis

Noise-induced tinnitus and hyperacusis are thought to correspond to a disrupted balance between excitation and inhibition in the central auditory system. Excitation and inhibition are often studied using pure tones; however, these responses do not reveal inhibition within the excitatory pass band. Therefore, we used a Wiener-kernel analysis, complemented with singular value decomposition (SVD), to investigate the immediate effects of acoustic trauma on excitation and inhibition in the inferior colliculus (IC).Neural responses were recorded from the IC of three anesthetized albino guinea pigs before and immediately after a one-hour bilateral exposure to an 11-kHz tone of 124 dB SPL. Neural activity was recorded during the presentation of a 1-h continuous 70 dB SPL Gaussian-noise stimulus. Spike trains were subjected to Wiener-kernel analysis in which the second-order kernel was decomposed into excitatory and inhibitory components using SVD.Hearing thresholds between 3 and 22 kHz were elevated (13–47 dB) immediately after acoustic trauma. The presence and frequency tuning of excitation and inhibition in units with a low characteristic frequency (CF; < 3 kHz) was not affected, inhibition disappeared whereas excitation was not affected in mid-CF units (3 < CF < 11 kHz), and both excitation and inhibition disappeared in high-CF units (CF > 11 kHz). This specific differentiation could not be identified by tone-evoked receptive-field analysis, in which inhibitory responses disappeared in all units, along with excitatory responses in high-CF units.This study is the first to apply Wiener-kernel analysis, complemented with SVD, to study the effects of acoustic trauma on spike trains derived from the IC. With this analysis, a reduction of inhibition and preservation of good response thresholds was shown in mid-CF units immediately after acoustic trauma. These neurons may mediate noise-induced tinnitus and/or hyperacusis. Moreover, an immediate profound high-frequency hearing loss was reflected by reduced evoked firing rates and loss of both excitation and inhibition in high-CF units.

Sunlight inhibits growth and induces markers of programmed cell death in Plasmodium falciparum in vitro

BackgroundPlasmodium falciparum is responsible for the majority of global malaria deaths. During the pathogenic blood stages of infection, a rapid increase in parasitaemia threatens the survival of the host before transmission of slow-maturing sexual parasites to the mosquito vector to continue the life cycle. Programmed cell death (PCD) may provide the parasite with the means to control its burden on the host and thereby ensure its own survival. Various environmental stress factors encountered during malaria may induce PCD in P. falciparum. This study is the first to characterize parasite cell death in response to natural sunlight.MethodsThe 3D7 strain of P. falciparum was cultured in vitro in donor erythrocytes. Synchronized and mixed-stage parasitized cultures were exposed to sunlight for 1 h and compared to cultures maintained in the dark, 24 h later. Mixed-stage parasites were also subjected to a second one-hour exposure at 24 h and assessed at 48 h. Parasitaemia was measured daily by flow cytometry. Biochemical markers of cell death were assessed, including DNA fragmentation, mitochondrial membrane polarization and phosphatidylserine externalization.ResultsSunlight inhibited P. falciparum growth in vitro. Late-stage parasites were more severely affected than early stages. However, some late-stage parasites survived exposure to sunlight to form new rings 24 h later, as would be expected during PCD whereby only a portion of the population dies. DNA fragmentation was observed at 24 and 48 h and preceded mitochondrial hyperpolarization in mixed-stage parasites at 48 h. Mitochondrial hyperpolarization likely resulted from increased oxidative stress. Although data suggested increased phosphatidylserine externalization in mixed-stage parasites, results were not statistically significant.ConclusionThe combination of biochemical markers and the survival of some parasites, despite exposure to a lethal stimulus, support the occurrence of PCD in P. falciparum.

Mineralocorticoid exposure and receptor activity modulate microvascular endothelial function in African Americans with and without hypertension.

Prior work suggests blood pressure in African Americans is more sensitive to the effects of aldosterone than in Caucasians. This mechanism may relate to a negative response of the vascular endothelium to aldosterone, including reduced glucose-6-phosphate dehydrogenase (G6PD) activity. Thirty-three African Americans (11 hypertensives, 22 controls) without evidence of diabetes or metabolic syndrome completed the protocol. The protocol included measurement of in vivo microvascular endothelial function by digital pulse arterial tonometry and ex vivo measurement of endothelial function by videomicroscopy of arterioles obtained from these same subjects with and without exposure to aldosterone or spironolactone. Systemic and arteriolar G6PD activities were also measured. In vivo and ex vivo microvascular endothelial function were impaired in African Americans with hypertension. One-hour exposure with aldosterone impaired endothelium-dependent vasodilation in arterioles from normotensive subjects, while 1 hour of spironolactone exposure reversed endothelial dysfunction in arterioles from hypertensive subjects. G6PD activity was impaired in hypertensive arterioles. Aldosterone-related endothelial dysfunction may be responsible for at least a portion of the greater blood pressure sensitivity to aldosterone in African Americans. This may be in part related to vascular suppression of G6PD activity.

Environmental Stability and Residual Stresses in Zirconia Femoral Head for Total Hip Arthroplasty: In Vitro Aging versus Retrieval Studies.

The objective of this study was to compare the low temperature degradation (LTD) behavior of femoral heads made of 3Y-TZP as observed on retrievals with that induced in vitro upon prolonged exposures to a hydrothermal environment. The time-dependent evolution of tetragonal-to-monoclinic transformation and the related residual stresses were nondestructively monitored by Raman microspectroscopy. An increasing intensification of tensile and compressive stresses was detected with increasing hydrothermal aging duration in tetragonal and monoclinic phases, respectively. The dependence of monoclinic fraction upon exposure time was rationalized through the Mehl-Avrami-Johnson (MAJ) formalism in order to interpret the LTD process according to a two-step mechanism of formation and growth of monoclinic nuclei. In vitro results were compared to in vivo monoclinic contents in the same type of 3Y-TZP head retrievals after implantation periods of 1.6–16.6 y, also including literature data previously reported by other authors. One-hour exposure under the selected aging condition is estimated to correspond to in vivo exposures of 4 and 2 years according to ISO and ASTM criteria, respectively. A critical review of these two criteria according to the present analyses revealed that the ASTM simulation predicts more closely the in vivo results as compared to the ISO one.

Repellent and insecticidal efficacy of a new combination of fipronil and permethrin against stable flies (Stomoxys calcitrans).

BackgroundA laboratory study was conducted to assess the repellent and insecticidal efficacy of a new combination of fipronil and permethrin (Frontline Tri- Act®/Frontect® Merial) against Stomoxys calcitrans (stable flies).MethodsSixteen dogs were allocated to two treatment groups. Eight dogs were treated with a new topical spot-on formulation containing 6.76% w/v fipronil + 50.48% w/v permethrin on Day 0 and eight dogs served as untreated controls. Each dog was exposed to approximately 100 stable flies on Days 1, 7, 14, 21, 28 and 35. After a one-hour exposure period, live flies were carefully aspirated into a vial, anesthetized with CO2 and crushed to determine feeding status (fed or unfed). Any dead flies remaining on the dog or in the cage were crushed to determine feeding status and counted as fed or unfed. Repellency was defined as the percent reduction in the number of fed flies in the treated group as compared to the untreated control group, and insecticidal efficacy was defined as the reduction in the number of live flies at the end of each exposure period in the treated group as compared to the control group.ResultsPercent repellency was ≥96.6% through Day 28, and 88.7% on Day 35. Percent insecticidal efficacy was ≥ 98.3% through Day 35.ConclusionsA single topical administration of a new combination of fipronil and permethrin provides protection (repellency and insecticidal efficacy) from S. calcitrans on dogs for at least 5 weeks.

Disruption of ion-trafficking system in the cochlear spiral ligament prior to permanent hearing loss induced by exposure to intense noise: possible involvement of 4-hydroxy-2-nonenal as a mediator of oxidative stress.

Noise-induced hearing loss is at least in part due to disruption of endocochlear potential, which is maintained by various K+ transport apparatuses including Na+, K+-ATPase and gap junction-mediated intercellular communication in the lateral wall structures. In this study, we examined the changes in the ion-trafficking-related proteins in the spiral ligament fibrocytes (SLFs) following in vivo acoustic overstimulation or in vitro exposure of cultured SLFs to 4-hydroxy-2-nonenal, which is a mediator of oxidative stress. Connexin (Cx)26 and Cx30 were ubiquitously expressed throughout the spiral ligament, whereas Na+, K+-ATPase α1 was predominantly detected in the stria vascularis and spiral prominence (type 2 SLFs). One-hour exposure of mice to 8 kHz octave band noise at a 110 dB sound pressure level produced an immediate and prolonged decrease in the Cx26 expression level and in Na+, K+-ATPase activity, as well as a delayed decrease in Cx30 expression in the SLFs. The noise-induced hearing loss and decrease in the Cx26 protein level and Na+, K+-ATPase activity were abolished by a systemic treatment with a free radical-scavenging agent, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, or with a nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester hydrochloride. In vitro exposure of SLFs in primary culture to 4-hydroxy-2-nonenal produced a decrease in the protein levels of Cx26 and Na+, K+-ATPase α1, as well as Na+, K+-ATPase activity, and also resulted in dysfunction of the intercellular communication between the SLFs. Taken together, our data suggest that disruption of the ion-trafficking system in the cochlear SLFs is caused by the decrease in Cxs level and Na+, K+-ATPase activity, and at least in part involved in permanent hearing loss induced by intense noise. Oxidative stress-mediated products might contribute to the decrease in Cxs content and Na+, K+-ATPase activity in the cochlear lateral wall structures.

Effects of melatonin on Wi-Fi-induced oxidative stress in lens of rats

Introduction:Melatonin has been considered a potent antioxidant that detoxifies a variety of reactive oxygen species in many pathophysiological states of eye. The present study was designed to determine the effects of Wi-Fi exposure on the lens oxidant, antioxidant redox systems, as well as the possible protective effects of melatonin on the lens injury induced by electromagnetic radiation (EMR).Materials and Methods:Thirty-two rats were used in the current study and they were randomly divided into four equal groups as follows: First and second groups were cage-control and sham-control rats. Rats in third group were exposed to Wi-Fi (2.45 GHz) for duration of 60 min/day for 30 days. As in the third group, the fourth group was treated with melatonin. The one-hour exposure to irradiation in second, third and fourth took place at noon each day.Results:Lipid peroxidation levels in the lens were slightly higher in third (Wi-Fi) group than in cage and sham control groups although their concentrations were significantly (P < 0.05) decreased by melatonin supplementation. Glutathione peroxidase (GSH-Px) activity was significantly (P < 0.05) lower in Wi-Fi group than in cage and sham control groups although GSH-Px (P < 0.01) and reduced glutathione (P < 0.05) values were significantly higher in Wi-Fi + melatonin group than in Wi-Fi group.Conclusions:There are poor oxidative toxic effects of one hour of Wi-Fi exposure on the lens in the animals. However, melatonin supplementation in the lens seems to have protective effects on the oxidant system by modulation of GSH-Px activity.

Skin can control solar UVR-induced mutations through the epidermis-specific response of mutation induction suppression

Skin exposure to solar ultraviolet radiation (UVR) has been a major public concern because of its genotoxicity. We established recently three action spectra of UVR biological effects using inflammation, mutagenicity, and mutation induction suppression (MIS) as indicators to evaluate UVR risk for mammalian skin. MIS is an antigenotoxic epidermis-specific response by which the increase of the mutant frequency (MF) levels off above a certain UVR dose. Here, based on these spectra, the mutation load of the skin after sunlight exposure was evaluated utilizing the spectral solar-UVR intensity data which had been measured at Tsukuba, Japan by the Japan Meteorological Agency. We estimated the daily variation of the solar-UVR effectiveness (effect per second) for the three indicators, and revealed that the effectiveness efficiency (effect per dose) of midday sunlight is 3-4-fold higher than those in the early morning and late afternoon. Based on the daily variations of mutagenicity and MIS effectiveness, we further estimated MFs induced after every one-hour sunlight exposure and reached a remarkable prediction that MFs should be suppressed to a constant level during 9:00-15:00 by MIS. The estimates agreed well with the equivalent values directly determined at Sendai, a site close to Tsukuba, although a small difference was detected for the epidermis at the dose range where the suppressed MFs were predicted. We propose the use of observed minimum inflammation/erythema doses to improve the difference. Our method could provide reliable estimates of sunlight genotoxicity to evaluate skin cancer probabilities.

Expression of maternal behavior and activation of the bed nucleus of the stria terminalis during predatory threat exposure: Modulatory effects of transport stress

Past work has established that levels of maternal care provided to rat pups during the postpartum period plays an important role in shaping development of the stress response system, such that high levels of pup licking and grooming and active nursing behaviors are associated with more efficient hypothalamic–pituitary–adrenal responses to stressors in adulthood. Furthermore, a prior study from our laboratory has demonstrated facilitation of maternal care for five days following a one-hour predator odor exposure on the day of giving birth. The present study was an investigation of the effects on maternal care during a one-hour predator odor exposure administered on the day of giving birth, with or without the addition of transport stress immediately prior to the odor exposure. Stress-induced activation of the medial preoptic area (MPOA) and the bed nucleus of the stria terminalis (BNST), two brain regions involved in regulating maternal behaviors, were also quantified using c-Fos immunohistochemistry. Our results show that predator odor exposure soon after birth does not significantly alter expression of maternal behaviors during the hour-long exposure period, unless the dams are also exposed to transport stress, in which case maternal behaviors are reduced during the first 10min of the exposure but not significantly different during the final 10min. Predator odor exposure (with or without additional transport stress) increased c-Fos immunoreactivity in the BNST, but not the MPOA, relative to control odor exposure, suggesting that the BNST may play an important role in integration of threat cues and transduction of their meaning into long-term effects on expression of maternal care. Future experiments should be designed to test the effects of temporary inactivation of the BNST during postpartum predator odor exposure.

Changes in ion transport through membranes, ATPase activity and antibiotics effects in Enterococcus hirae after low intensity electromagnetic irradiation of 51.8 and 53.0 GHz frequencies

It was ascertained that one-hour exposure of Enterococcus hirae ATCC9790 bacteria grown under anaerobe condition during sugar (glucose) fermentation to coherent electromagnetic irradiation (EMI) of 51,8 and 53,0 GHz frequencies or millimeter waves (5,79 and 5,66 mm wavelengths) of low-intensity (flux capacity of 0,06 mW/sm2) caused a significant decrease in energy-dependent H+ and K+ transports across the membranes of whole cells. Therewith, K+ influx into cells was appreciably less at the frequency of 53,0 GHz. Likewise, a significant decrease of total and N,N'-dicyclohexylcarbodiimide-sensitive ATPase activity of the membrane vesicles occurred after EMI of 51,8 and 53,0 GHz. These results indicated the input of membranous changes in bacterial action of low intensity extremely high frequency EMI, when the F0F1-ATPase was probably playing a key role. Additionally, the enhancement of the effects of antibiotics--ceftriaxone, kanamycin and ampicillin at their minimal inhibitory concentrations (100, 200 and 1,4 microM, correspondingly) on the bacterial growth by these irradiations was shown. Also, combined action of EMI and antibiotics depressed strongly H+ and K+ fluxes across membrane. Especially, H+ flux was more sensitive to the action of ceftriaxone, but K+ flux was sensitive to kanamycin. All these made the assumption that EMI of 51,8 and 53,0 GHz frequencies, especially 53,0 GHz, was followed by change in bacterial sensitivity toward antibiotics that was more obvious with ceftriaxone and ampicillin.

Rapid Cytotoxicity of Antimicrobial Peptide Tempoprin-1CEa in Breast Cancer Cells through Membrane Destruction and Intracellular Calcium Mechanism

Temporin-1CEa is an antimicrobial peptide isolated from the skin secretions of the Chinese brown frog (Rana chensinensis). We have previously reported the rapid and broad-spectrum anticancer activity of temporin-1CEa in vitro. However, the detailed mechanisms for temporin-1CEa-induced cancer cell death are still weakly understood. In the present study, the mechanisms of temporin-1CEa-induced rapid cytotoxicity on two human breast cancer cell lines, MDA-MB-231 and MCF-7, were investigated. The MTT assay and the LDH leakage assay indicated that one-hour of incubation with temporin-1CEa led to cytotoxicity in a dose-dependent manner. The morphological observation using electronic microscopes suggested that one-hour exposure of temporin-1CEa resulted in profound morphological changes in both MDA-MB-231 and MCF-7 cells. The membrane-disrupting property of temporin-1CEa was further characterized by induction of cell-surface exposure of phosphatidylserine, elevation of plasma membrane permeability and rapid depolarization of transmembrane potential. Moreover, temporin-1CEa evoked intracellular calcium ion and reactive oxygen species (ROS) elevations as well as collapse of mitochondrial membrane potential (Δφm). In summary, the present study indicates that temporin-1CEa triggers rapid cell death in breast cancer cells. This rapid cytotoxic activity might be mediated by both membrane destruction and intracellular calcium mechanism.

Metabolic Alterations of the Zebrafish Brain after Acute Alcohol Treatment by1H Nuclear Magnetic Resonance Spectroscopy

The purpose of this study is to investigate the metabolic alterations associated with acute alcohol treatment in zebrafish by1H nuclear magnetic resonance spectroscopy (NMRS). The brain metabolism of zebrafish was investigated after acute alcohol treatment (one-hour long exposure of adult fish to 0.00%, 0.25%, 0.50%, or 1.00% ethyl alcohol) with whole brain extraction. The results of this study showed that glutamate (Glu) was significantly decreased, scyllo-inositol (sIns) showed a small apparent increase only in the highest acute treatment dose group, and myoinositol (mIns) showed a significant decrease. [Glu]/[tCr] and [mIns]/[tCr] levels were significantly reduced regardless of the alcohol dose, and [sIns]/[tCr] was increased in the highest alcohol treatment dose group. The present NMR study revealed that specific metabolites, such as Glu and mIns, were substantially decreased in case of acute alcohol exposed zebrafish brain.

Secondhand smoke exposure induces acutely airway acidification and oxidative stress

Previous studies have shown that secondhand smoke induces lung function impairment and increases proinflammatory cytokines. The aim of the present study was to evaluate the acute effects of secondhand smoke on airway acidification and airway oxidative stress in never-smokers. In a randomized controlled cross-over trial, 18 young healthy never-smokers were assessed at baseline and 0, 30, 60, 120, 180 and 240min after one-hour secondhand smoke exposure at bar/restaurant levels. Exhaled NO and CO measurements, exhaled breath condensate collection (for pH, H(2)O(2) and NO(2)(-)/NO(3)(-) measurements) and spirometry were performed at all time-points. Secondhand smoke exposure induced increases in serum cotinine and exhaled CO that persisted until 240min. Exhaled breath condensate pH decreased immediately after exposure (p<0.001) and returned to baseline by 180min, whereas H(2)O(2) increased at 120min and remained increased at 240min (p=0.001). No changes in exhaled NO and NO(2)/NO(3) were observed, while decreases in FEV(1) (p<0.001) and FEV(1)/FVC (p<0.001) were observed after exposure and returned to baseline by 180min. A 1-h exposure to secondhand smoke induced airway acidification and increased airway oxidative stress, accompanied by significant impairment of lung function. Despite the reversal in EBC pH and lung function, airway oxidative stress remained increased 4h after the exposure. Clinical trial registration number (EudraCT): 2009-013545-28.

Exposure of Pseudomonas aeruginosa to green tea polyphenols enhances the tolerance to various environmental stresses

Green tea polyphenols (GTP) are widely used as food preservatives and are considered to be extremely safe. However, the bacterial response to GTP has not been well studied. Here we investigated whether short exposure of Pseudomonas aeruginosa to sub-lethal dose of GTP could lead to cross-resistance to some environmental stresses. One-hour exposure of P. aeruginosa to 1 mg/ml GTP significantly increased the tolerance to oxidants (2 mM H(2)O(2), 4 mM tert-butylhydroperoxide), low pH solution (pH 4.0) containing various organic acids (60 mM citric, acetic, propionic or lactic acid) and other stress conditions (47 °C, 25 % NaCl, 12 % ethanol and 150 μg/ml crystal violet). The development of H(2)O(2) tolerance in GTP-exposed cells was prevented by chloramphenicol, a well-known inhibitor of protein synthesis in prokaryotic cells. Furthermore, we observed significantly increased catalase activity after GTP exposure, suggesting that P. aeruginosa develops GTP-induced cross-resistance by increasing synthesis of protective protein. These observations raise concerns over the underlying risks associated with using GTP as food preservatives.

A higher illuminance induces alertness even during office hours: Findings on subjective measures, task performance and heart rate measures

Nocturnal white light exposure has shown marked results on subjective and objective indicators of alertness, vitality and mood, yet effects of white light during daytime and under usual office work conditions have not been investigated extensively. The current study employed a mixed-group design (N=32), testing effects of two illuminance levels (200lx or 1000lx at eye level, 4000K) during one hour of morning versus afternoon exposure. In four repeated blocks, subjective reports, objective performance and physiological arousal were measured. Results showed effects of illuminance on subjective alertness and vitality, sustained attention in tasks, and heart rate and heart rate variability. Participants felt less sleepy and more energetic in the high versus the low lighting condition, had shorter reaction times on the psychomotor vigilance task and increased physiological arousal. Effects of illuminance on the subjective measures, as well as those on heart rate were not dependent on time of day or duration of exposure. Performance effects were most pronounced in the morning sessions and towards the end of the one-hour exposure period. The effect on heart rate variability was also most pronounced at the end of the one-hour exposure. The results demonstrate that even under normal, i.e., neither sleep nor light deprived conditions, more intense light can improve feelings of alertness and vitality, as well as objective performance and physiological arousal.

Long lasting macrophage cytokine suppression by alpha 7 nAChR requires JAK/STAT (138.23)

Abstract The central nervous system regulates innate immunity reflexively, as action potentials transmitted in the vagus nerve suppress cytokine release during endotoxemia. The mechanism of cytokine release by this neural circuit requires signaling through the alpha 7 nicotinic acetylcholine receptor (a7 nAChR), but the duration of this protection is incompletely understood. Electrical vagus nerve stimulation (VNS) in mice significantly inhibited serum TNF levels during endotoxemia, even when endotoxin was given 2, 24 or 48 h after VNS. This inhibition of TNF was abolished in a7 nAChR deficient mice, confirming the mechanism that requires this receptor. One-hour exposure of human macrophages to acetylcholine in vitro reduced endotoxin-induced increases in IKKbeta, IkappaBalpha activity and TNF release for up to 24 h after removal of acetylcholine. Levels of Supressor of Cytokine Signaling 1-3, A20, BCL3, IkappaBNS and IkappaBzeta were not altered in human macrophages 15 min to 8 h after exposure to acetylcholine, but exposure of macrophages to the selective JAK/STAT inhibitor AG490 abolished the cytokine suppressing effect of acetylcholine. Together with previous work indicating that JAK/STAT forms a signaling complex with a7 nAChR, these results suggest that JAK/STAT activation is required for long lasting suppression of macrophage cytokine release after transient exposure to acetylcholine.

Phosphorylation of phosphatidylinositol-3-kinase-protein kinase B and extracellular signal-regulated kinases 1/2 mediate reoxygenation-induced cardioprotection during hypoxia

In vivo exposure to chronic hypoxia (CH) depresses myocardial performance and tolerance to ischemia, but daily reoxyenation during CH (CHR) confers cardioprotection. To elucidate the underlying mechanism, we tested the role of phosphatidylinositol-3-kinase-protein kinase B (Akt) and p42/p44 extracellular signal-regulated kinases (ERK1/2), which are known to be associated with protection against ischemia/reperfusion (I/R). Male Sprague-Dawley rats were maintained for two weeks under CH (10% O(2)) or CHR (as CH but with one-hour daily exposure to room air). Then, hearts were either frozen for biochemical analyses or Langendorff-perfused to determine performance (intraventricular balloon) and tolerance to 30-min global ischemia and 45-min reperfusion, assessed as recovery of performance after I/R and infarct size (tetrazolium staining). Additional hearts were perfused in the presence of 15 micromol/L LY-294002 (inhibitor of Akt), 10 micromol/L UO-126 (inhibitor of ERK1/2) or 10 micromol/L PD-98059 (less-specific inhibitor of ERK1/2) given 15 min before ischemia and throughout the first 20 min of reperfusion. Whereas total Akt and ERK1/2 were unaffected by CH and CHR in vivo, in CHR hearts the phosphorylation of both proteins was higher than in CH hearts. This was accompanied by better performance after I/R (heart rate x developed pressure), lower end-diastolic pressure and reduced infarct size. Whereas the treatment with LY-294002 decreased the phosphorylation of Akt only, the treatment with UO-126 decreased ERK1/2, and that with PD-98059 decreased both Akt and ERK1/2. In all cases, the cardioprotective effect led by CHR was lost. In conclusion, in vivo daily reoxygenation during CH enhances Akt and ERK1/2 signaling. This response was accompanied by a complex phenotype consisting in improved resistance to stress, better myocardial performance and lower infarct size after I/R. Selective inhibition of Akt and ERK1/2 phosphorylation abolishes the beneficial effects of the reoxygenation. Therefore, Akt and ERK1/2 have an important role to mediate cardioprotection by reoxygenation during CH in vivo.

Effect of Thai ‘koi-hoi’ food flavoring on the viability and infectivity of the third-stage larvae of Angiostrongylus cantonensis (Nematoda: Angiostrongylidae)

The effect of the food flavoring of ‘koi-hoi’, a popular Thai snail dish, on the viability and infectivity of Angiostrongylus (= Parastrongylus) cantonensis third-stage larvae was assessed in a mouse model. Groups of 50 each of actively moving, non-motile coiled, and extended larvae were obtained from experimentally infected snail meat, after one-hour exposure to standard ‘koi-hoi’ flavoring. These larvae and groups of 50 unexposed moving larvae (control) were individually fed to each group of three experimental BALB/c mice. The effect on Angiostrongylus worm burden was measured after 3 weeks of infection. Infectivity of the motile larvae after exposure to ‘koi-hoi’ food flavoring was 38 ± 5.29%. This was highly significantly lower than the infectivity (62 ± 7.21%) of the control (unexposed) third-stage larvae ( χ 2 = 17.28, P < 0.001). In the non-motile larvae resulting from exposure to the food flavoring, no adult worm was recovered from the extended larvae, indicating that they were no longer alive and unable to cause infection. A small proportion (3.33 ± 2.31%) of the coiled larvae developed into young adult worms, indicating that mobility alone is not a definitive indicator of viability. The present study confirms that the food flavoring components of ‘koi-hoi’ dish adversely affect the viability and infectivity of A. cantonensis larvae. Exposure of the third-stage larvae to ‘koi-hoi’ food flavoring resulted in decreased viability and eventually death. Prolonged treatment with food flavoring to inactivate/immobilize and then kill the infective, third-stage larvae of A. cantonensis in snail meat prior to consumption may be one of the possible economical means of reducing human infection.

The effect of low-intensity coherent extremely high frequency electromagnetic radiation on growth parameters for Enterococcus hirae bacteria

It is found that for Enterococcus hirae ATCC9790 bacteria grown in anaerobic conditions, one-hour exposure to low-intensity (radiant power of 0.06 mW/cm2) coherent extremely high frequency electromagnetic radiation (from 45 to 53 GHz), or millimeter electromagnetic radiation, leads to an appreciable increase in latent growth time and to a decrease in specific growth rate; herein, the effects intensify as the frequency increases from 49 to 53 GHz. The result is enhanced at an increase in the radiation duration from 30 min to 1 h; however, a further increase in the exposure time up to 2 h does not lead to intensification of the effect. It is shown that the effect of extremely high frequency electromagnetic radiation on Enterococcus hirae does not depend on pH of the medium (pH 6.0 or 8.0). It may be expected that these bacteria have protective or reparation mechanisms that compensate long-term action of this radiation; it is not improbable that various mechanisms of pH regulation are present as well.