Reversal of depressed miduterine arterial flow during hyperthermia-induced respiratory alkalosis

The influence of ambient and arterial PCO2 on miduterine arterial flow of pregnant sheep acutely exposed to hot environments was investigated. Five mixed-breed ewes between 120 and 130 days of gestation were subjected to hot environments (increasing from thermoneutral 23 to 40 degrees C), and arterial blood pH, PCO2, and PO2 were determined at 5-min intervals. Respiratory rate, heart rate, rectal temperature, blood pressure, and miduterine arterial flow were continuously monitored prior to and during elevation of ambient air temperature. When miduterine arterial flow had decreased to 50% of thermoneutral control levels, ambient air CO2 was increased to 2.5%. Elevated ambient inspired CO2 caused a reversal in arterial pH and PCO2 to near thermoneutral levels. Miduterine arterial flow increased to 77% of the control levels following the elevated ambient PCO2 period. Respiratory rate also decreased when ambient CO2 was increased but remained 136% greater than the thermoneutral control level. All other parameters remained near their heat stress (40 degrees C) level during the elevation of ambient CO2. These data indicate that heat-stress-induced depression of miduterine arterial flow is vasoactively regulated, and cause-effect related to both arterial pH and PCO2, and thermoregulatory shunting of blood to heat-dissipating surfaces.     

Prevention of hyperthermia-induced seizures in immature rats by a hydantoin derivative of naloxone

The non-specific opiate antagonist naloxone protects immature rats from hyperthermic seizures which occur when the animals are exposed to an environment of 40 degrees C and 55% humidity. Most of the currently used antiepileptic therapeutic agents can be said to contain either a hydantoin or a moiety stereochemically closely related to one. We have added a hydantoin group to naloxone and created a new combined chemical, naloxyl-6-alpha spirohydantoin. The new compound was ten times as effective as naloxone against hyperthermic seizures in 15-day old rat pups. Unlike naloxone, the new naloxone-hydantoin derivative retained a protective effect 24 hrs after injection.     

Ring chromosome 18 in a child with febrile seizures

Ring chromosomes are uncommon cytogenetic findings but have meanwhile been reported for nearly all human chromosomes. Among the rare observations of ring chromosomes in man, the diagnosis of ring chromosome 18 represents a prominent group. We here describe on the cytogenetic analysis results obtained for a 9 years old male patient of non-consanguineous parents. He had growth and developmental delay, mental and motor retardation, microcephaly, microphtalmia, triangle face, small dysplastic ears, strabismus, epicanthal folds on the left, short stature, cryptorchidism, spasticity, pes equinovarus, pes planus, hypothroidism, stereotypic movements and febrile seizures. Also he had hypomyelinization and multiple hyperintense focuses within the white matter on the MRI. The generalized epileptiform abnormality originated from bilateral Centroparietal region. The metabolic investigations including blood and urine amino acids and lysosomal screening tests were normal. The chromosome analysis identified [46,XY,r(18)/46,XY] in 35% of cells a ring 18 and in 65% of cells normal karyotype in peripheral blood cells examined by standard G-bands by Trypsin using Giemsa (GTG) analysis. The dysmorphic features of the presented patient are discussed to the identification of the genotype-phenotype correlation related to his karyotype.     

Long-term plasticity of endocannabinoid signaling induced by developmental febrile seizures

Febrile (fever-induced) seizures are the most common form of childhood seizures, affecting 3%-5% of infants and young children. Here we show that the activity-dependent, retrograde inhibition of GABA release by endogenous cannabinoids is persistently enhanced in the rat hippocampus following a single episode of experimental prolonged febrile seizures during early postnatal development. The potentiation of endocannabinoid signaling results from an increase in the number of presynaptic cannabinoid type 1 receptors associated with cholecystokinin-containing perisomatic inhibitory inputs, without an effect on the endocannabinoid-mediated inhibition of glutamate release. These results demonstrate a selective, long-term increase in the gain of endocannabinoid-mediated retrograde signaling at GABAergic synapses in a model of a human neurological disease.     

Attenuation of febrile seizures in epileptic chicks by N-methyl-D-aspartate receptor antagonists

Experimental febrile seizures can be evoked in epileptic chicks by elevation of their body temperature. Both competitive N-methyl-D-aspartate (NMDA) receptor antagonists [(3-(+/- )2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), DL-2-amino-7-phosphosphonoheptanoic acid (APH), DL-2-amino-5-phosphonovaleric acid (APV), D-alpha-aminoadipic acid (AAA), and DL-alpha, epsilon-diaminopimelic acid (DAP)] and the noncompetitive NMDA antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5, 10-imine maleate (MK-801) produced dose-dependent increases in latency to the onset of seizures. Of the drugs tested, MK-801 had the highest potency followed in order by CPP = APH greater than APV much greater than AAA greater than DAP. There was a high correlation (r = 0.995) between the dose capable of doubling seizure latency and the affinity of the competitive NMDA antagonists for the NMDA receptor as determined by in vitro binding assays. These data suggest that NMDA receptor mediated mechanisms may be involved in the production of seizures in response to hyperthermia.     

Hydrogen sulfide may improve the hippocampal damage induced by recurrent febrile seizures in rats

The aim of the present study was to investigate the possible role of hydrogen sulfide (H(2)S) in the pathogenesis of recurrent febrile seizures (FS) in rats. On a rat model of recurrent FS, the ultrastructure of hippocampal neurons, the plasma level of H(2)S, the expressions of cystathionine b-synthase (CBS) and c-fos, and the development of mossy fiber sprouting (MFS) in hippocampus were examined after treatment with NaHS, a donor of H(2)S, or hydroxylamine (HA), an inhibitor of CBS. We found that the plasma level of H(2)S increased significantly, the expressions of CBS and c-fos increased markedly, and MFS was evident in hippocampus in FS group. NaHS alleviated the neuronal damage of recurrent FS rats, decreased the expression of c-fos, and inhibited MFS obviously. HA aggravated the neuronal damage of recurrent FS rats, further increased the expression of c-fos, and enhanced the mossy fiber outgrowth. The results showed that endogenous H(2)S system was involved in the development of FS. Exogenous H(2)S may exert beneficial effect on the pathogenesis of FS-related brain damage.     

Enhancement of hyperthermia-induced apoptosis by a new synthesized class of benzocycloalkene compounds

The aim of this study was to examine whether, a new synthesized class of benzocycloalkene derivatives (BCs), enhances apoptosis induced by hyperthermia. The combined effects of hyperthermia (44°C, 20 min) and BCs on apoptosis in human lymphoma U937 cells were investigated. Among the tested compounds (BC1 ∼ 9), the combined treatment of 10 μM BC2 or BC4 and hyperthermia showed the largest potency to induce DNA fragmentation at 6 h after hyperthermia. And enhancement of hyperthermia-induced apoptosis by BC2 or BC4 in a dose-dependent manner was observed. When the cells were treated first with BC2 or BC4 at a nontoxic concentration of 20 μM, and exposed to hyperthermia afterwards, a significant enhancement of heat-induced apoptosis was evidenced by DNA fragmentation, morphological changes and phosphatidylserine externalization. Flow cytometry revealed an increase of intracellular superoxide due to BC2 or BC4, which was further increased when hyperthermia was combined. Mitochondrial membrane potential was decreased and the activation of caspase-3 and caspase-8 was enhanced in the cells treated with the combination. The activation of Bid, but no change of Bax and Bcl-2 were observed after the combined treatment. The release of cytochrome c from mitochondria to cytosol, which was induced by hyperthermia, was enhanced by BC2 or BC4. An increase in the intracellular Ca²⁺ concentration [Ca²⁺]_i, externalization of Fas, and decrease in Hsp70 were observed following the combined treatment. These results indicate that the intracellular superoxide generated by BC2 or BC4 is involved in the enhancement of apoptosis through Fas-mitochondria caspase and [Ca²⁺]_i-dependent pathways, and a decrease in Hsp70 also contributed to the enhancement of apoptosis.     

Two major proteins from locust plasma are involved in coagulation and are specifically precipitated by laminarin, a ß-1,3-glucan

Incubation of plasma of the locust Locusta migratoria, with laminarin induced the precipitation of two major proteins with molecular masses of about 260 000 (P260) and 85 000 Da (P85). This precipitation was not observed when other polysaccharides, such as curdlan, dextran, chitin, cellulose or mannan were used. P260 and P85 were purified to homogeneity by a single step on heparin-sepharose chromatography. Since all attempts to separate P260 from P85, other than the use of sodium dodecyl sulfate, were unsuccessful, it is likely that these two molecules form a complex non-covalently associated. Treatment of P260–P85 complex with N-glycosidase F showed that P260 did not appear to be glycosylated whereas 6% of P85 molecular mass was due to N-linked carbohydrates. On the other hand, no change in molecular masses of P260 or P85 was observed once the complex had been treated with lipase. SDS-PAGE and Western blots of plasma and serum stained with blue Coomassie for proteins or with highly specific polysera to P260 or P85, respectively, showed that P260 was only present in plasma and P85 remained in both samples. This indicates that P260 is likely to be one of the most abundant plasma proteins directly involved in the coagulation process in Locusta migratoria. The addition of plasma or P260–P85 complex to a hemocyte lysate supernatant prior to its activation by laminarin induced a lower protease as well as phenoloxidase activity compared with the control. This reduction of activities was not observed in the presence of serum or when P260–P85 complex was added to a fully activated proPO system.     

Enhancement of hyperthermia-induced apoptosis by a new synthesized class of furan-fused tetracyclic compounds

The combined effects of hyperthermia (44 degrees C, 20 min) or X-rays (10 Gy) and a new class of furan-fused tetracyclic synthesized compounds (DFs), on apoptosis in human lymphoma U937 cells were investigated. Among the tested compounds (DF1 approximately 6), the combined treatment of 10 microM DF with TIPS (triisopropylsilyloxy) (Designated #3 DF3) and hyperthermia showed the largest potency to induce DNA fragmentation at 6 h after hyperthermia but no enhancement was observed if it was combined with X-rays. Enhancement of hyperthermia-induced apoptosis by DF3 in a dose-dependent manner was observed. When the cells were treated first with DF3 at a nontoxic concentration of 20 microM, and exposed to hyperthermia afterwards, a significant enhancement of heat-induced apoptosis was evidenced by DNA fragmentation, morphological changes and phosphatidylserine externalization. The activation of Bid, but no change of Bax and Bcl-2 were observed after the combined treatment. The release of cytochrome c from mitochondria to cytosol, which was induced by hyperthermia, was enhanced by DF3. Mitochondrial transmembrane potential was decreased and the activation of caspase-3 and caspase-8 was enhanced in the cells treated with the combination. Externalization of Fas was observed following the combined treatment. Flow cytometry revealed rapid and sustained increase of intracellular superoxide due to DF3, and showed subsequent and transient increase in the formation of intracellular hydrogen peroxide (H(2)O(2)), which was further increased when hyperthermia was combined. These results indicate that the intracellular superoxide and H(2)O(2) generated by DF3 enhance the hyperthermia-induced apoptosis via the Fas-mediated mitochondrial caspase-dependent pathway.     

Transitions in insect respiratory patterns are controlled by changes in metabolic rate

We examined the respiratory patterns of Rhodnius prolixus and Gromphadorhina portentosa as metabolic rates varied with temperature to determine whether insects transition from discontinuous (DGC), cyclical and continuous respiration as a response to increasing aerobic demand. Using flow through respirometry we: (1) determined the effects of temperature on metabolic rate; (2) objectively defined periods of spiracular closure; (3) observed whether there was a correlation between metabolic rate and length of spiracular closure. At low temperatures both species exhibit lengthy periods of spiracular closure reflecting a discontinuous respiratory pattern. As metabolic rate increased, periods of spiracular closure decreased and insects displayed a more cyclical pattern of respiration. As metabolic rates increased even further under the highest experimental temperatures, periods of spiracular closure decreased even more and a continuous respiratory pattern was employed by both species. Our results suggest that the three described respiratory patterns in insects are not distinct but are instead a continuum of respiratory responses driven by the metabolic demand experienced by the insect.     

Experimental evidence that aboveground predators are sustained by underground detritivores

Detrital infusion into grazing food web is considered to be important in terrestrial communities, but there is hardly any experimental evidence showing that generalist predators aboveground are sustained by belowground detritivores. We established two types of experimental plots in the forest floor, one with sheets on the ground to prevent the emergence of belowground arthropods and the other without sheet, to test the hypotheses that 1) reduced input of detrital arthropods decreases the abundance and species richness of web spiders (major generalist predators in terrestrial ecosystems) and 2) lower number of spiders increases the abundance of herbivorous arthropods. We found that spiders were less abundant in plots where the emergence of detrital arthropods was reduced, while the abundance of herbivores did not significantly increase in these plots. These results provide empirical evidence that organisms moving from underground to aboveground may be important for the maintenance of aboveground predators, although the cascading effect of predator abundance on the grazing food chain was not detected in the present study.     

Contractions of specific abdominal muscles in postural tasks are affected by respiratory maneuvers

Hodges, Paul W., Simon C. Gandevia, and Carolyn A. Richardson. Contractions of specific abdominalmuscles in postural tasks are affected by respiratory maneuvers.J. Appl. Physiol. 83(3): 753-760, 1997.The influence of respiratory activity of the abdominal muscleson their reaction time in a postural task was evaluated. Theelectromyographic (EMG) onsets of the abdominal muscles and deltoidwere evaluated in response to shoulder flexion initiated by a visualstimulus occurring at random throughout the respiratory cycle.Increased activity of the abdominal muscles was produced by inspiratoryloading, forced expiration below functional residual capacity, and astatic glottis-closed expulsive maneuver. During quiet breathing, thelatency between activation of the abdominal muscles and deltoid was notinfluenced by the respiratory cycle. When respiratory activity of theabdominal muscles increased, the EMG onset of transversus abdominis andinternal oblique, relative to deltoid, was significantly earlier formovements beginning in expiration, compared with inspiration [by97-107 ms (P < 0.01) and64-90 ms (P < 0.01),respectively]. However, the onset of transversus abdominis EMGwas delayed by 31-54 ms (P < 0.01) when movement was performed during a static expulsive effort,compared with quiet respiration. Thus changes occur in earlyanticipatory contraction of transversus abdominis during respiratorytasks but they cannot be explained simply by existing activation of themotoneuron pool.

     

Experimental neonatal respiratory failure induced by lysophosphatidylcholine: effect of surfactant treatment

The purpose of this study was to characterize the toxic effectsof lysophosphatidylcholine (lyso-PC) on neonatal lung function. Variousdoses of lyso-PC (from 0 to 40 mg/kg) were administered to near-termnewborn rabbits. Lung-thorax compliance during mechanical ventilationwas significantly decreased by doses 10 mg/kg, and static lungvolumes during deflation were decreased by doses 20 mg/kg. Using thesame experimental model, we investigated the effects of modifiedporcine surfactant (Curosurf, 200 mg/kg). Animals exposed to lyso-PC atbirth and treated simultaneously with surfactant showed a satisfactorytherapeutic response, whereas those treated after 30 min failed torespond. These animals also had a much larger leak of albumin into theair spaces and an elevated minimum surface tension of the lavage fluidin a pulsating bubble surfactometer, suggesting inactivation of theexogenous surfactant. Timing of surfactant administration may thus beessential for the therapeutic effect in this experimental model ofacute lung injury.     

Enhancement of hyperthermia-induced apoptosis by 5Z-7-oxozeaenol,a TAK1 inhibitor,in A549 cells

KRAS mutant lung cancers have long been considered as untreatable with drugs. Transforming growth factor-β-activated kinase 1 (TAK1) appears to play an anti-apoptotic role in response to multiple stresses and has been reported to be a responsive kinase that regulates cell survival in KRAS-dependent cells. In this study, in order to find a useful approach to treat KRAS mutant lung cancer, we focused on the combined effects of 5Z-7-oxozeaenol, a TAK1 inhibitor, with hyperthermia (HT) in KRAS mutant lung cancer cell line A549. Annexin V-FITC/PI assay, cell cycle analysis, and colony formation assay revealed a significant enhancement in apoptosis induced by HT treatment, when the cells were pre-incubated with 5Z-7-oxozeaenol in a dose-dependent manner. The enhanced apoptosis by 5Z-7-oxozeaenol was accompanied by a significant increase in reactive oxygen species (ROS) generation and loss of mitochondrial membrane potential (MMP). In addition, western blot showed that 5Z-7-oxozeaenol enhanced HT-induced expressions of cleaved caspase-3, cleaved caspase-8, and HSP70 and decreased HT-induced expressions of Bcl-2, p-p38, p-JNK, and LC3. Moreover, 5Z-7-oxozeaenol pre-treatment resulted in a marked elevation of intracellular calcium level which might be associated with endoplasmic reticulum (ER) stress-related pathway. Taken together, our data provides further insights of the mechanism of action of 5Z-7-oxozeaenol and HT treatment, and their potential application as a novel approache to treat patients with KRAS mutant lung cancer.     

Th17 cytokines are critical for respiratory syncytial virus-associated airway hyperreponsiveness through regulation by complement C3a and tachykinins

Respiratory syncytial virus (RSV) infection is associated with serious lung disease in infants and immunocompromised individuals and is linked to development of asthma. In mice, acute RSV infection causes airway hyperresponsiveness (AHR), inflammation, and mucus hypersecretion. Infected cells induce complement activation, producing the anaphylatoxin C3a. In this paper, we show RSV-infected wild-type mice produce Th17 cytokines, a response not previously associated with viral infections. Mice deficient in the C3aR fail to develop AHR following acute RSV infection, and production of Th17 cytokines was significantly attenuated. Tachykinin production also has been implicated in RSV pathophysiology, and tachykinin receptor-null mice were similarly protected from developing AHR. These animals were also deficient in production of Th17 cytokines. Tachykinin release was absent in mice deficient in C3aR, whereas C3a levels were unchanged in tachykinin receptor-null animals. Thus, our data reveal a crucial sequence following acute RSV infection where initial C3a production causes tachykinin release, followed by activation of the IL-17A pathway. Deficiency of either receptor affords protection from AHR, identifying two potential therapeutic targets.     

CD8 T cells are essential for recovery from a respiratory vaccinia virus infection

The precise immune components required for protection against a respiratory Orthopoxvirus infection, such as human smallpox or monkeypox, remain to be fully identified. In this study, we used the virulent Western Reserve strain of vaccinia virus (VACV-WR) to model a primary respiratory Orthopoxvirus infection. Naive mice infected with VACV-WR mounted an early CD8 T cell response directed against dominant and subdominant VACV-WR Ags, followed by a CD4 T cell and Ig response. In contrast to other VACV-WR infection models that highlight the critical requirement for CD4 T cells and Ig, we found that only mice deficient in CD8 T cells presented with severe cachexia, pulmonary inflammation, viral dissemination, and 100% mortality. Depletion of CD8 T cells at specified times throughout infection highlighted that they perform their critical function between days 4 and 6 postinfection and that their protective requirement is critically dictated by initial viral load and virulence. Finally, the ability of adoptively transferred naive CD8 T cells to protect RAG(-/-) mice against a lethal VACV-WR infection demonstrated that they are both necessary and sufficient in protecting against a primary VACV-WR infection of the respiratory tract.