The interplay between receptor capping and cytoskeleton remodeling in Entamoeba histolytica.
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Animals↗
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Opposing interplay between Neuropeptide FF and nitric oxide in antinociception and hypothermia.
This study examined the ability of the anti-opioid Neuropeptide FF (NPFF) to modify the endogenous activity of nitric oxide (NO). Antinociceptive and hypothermic effects of 1DMe (D.Tyr-Leu-(n.Me)Phe-Gln-Pro-Gln-Arg-Phe-NH(2)), an NPFF agonist, and of L-NAME (N(omega)nitro-L-arginine methyl ester), an inhibitor of nitric oxide synthase, were investigated in mice. Intraperitoneal (i.p.) injection of L-NAME induced, in the hot plate test, a dose-dependent antinociception not reversed by naloxone, an opioid antagonist, but inhibited by L-Arg, the NO synthesis precursor. Intracerebroventricular (i.c.v.) injections of 1DMe inhibit the antinociceptive activity of L-NAME in a dose-dependent manner. On the contrary, L-NAME markedly potentiated hypothermia induced by 1DMe injected in the third ventricle. These data show that Neuropeptide FF receptors exert a dual effect on endogenous NO functions and could modulate pain transmission independently of opioids.
Analgesics, Opioid↗
Interplay between high energy impulse noise (blast) and antioxidants in the lung.
High-energy impulse noise (BLAST) is a physical event characterized by an abrupt rise in atmospheric pressure above ambient lasting for a very short period, but potentially causing significant material and biological damage. Exposure to high-level BLAST can be destructive and lethal. Low-level BLAST similar to what is encountered repeatedly by military personnel during training and combat from detonation of munitions and firing of large caliber weapons, and during occupational use of explosives and some heavy machinery, can also cause significant injury. Globally, civilians are increasingly exposed to BLAST resulting from terrorist bombings or abandoned unmarked mines following numerous wars and conflicts. We have shown previously in several animal models that exposure to non-lethal BLAST results in pathological changes, mostly to the hollow organs characterized in the lungs, the most sensitive organ, by rupture of alveolar septa, and pulmonary hemorrhage and edema. These events potentially can cause alveolar flooding, respiratory insufficiency and adult respiratory distress syndrome (ARDS), leading to varying degrees of hypoxia, antioxidant depletion and oxidative damage. We have also observed progressive formation of nitric oxide in blood and other tissues. The totality of these observations supports our general hypothesis that exposure to BLAST can lead to antioxidant depletion and oxidative damage. Understanding the mechanism(s) of BLAST-induced oxidative stress may have important implications that include a potential beneficial role for antioxidants as a prophylaxis or as secondary treatment of injury after exposure alongside other protective and therapeutic modalities. In addition, it suggests a role for endogenous nitric oxide in the injury. This report reviews experimental evidence of BLAST-induced antioxidant depletion, and the potential benefit from antioxidant supplementation before exposure.
Animals↗
Interplay between membrane dynamics, diffusion and swelling pressure governs individual vesicular exocytotic events during release of adrenaline by chromaffin cells.
Release of adrenaline by chromaffin cells occurs through a process involving docking and then fusion of a secretory vesicle to the cytoplasmic membrane of the cell. Fusion proceeds in two main stages. The first one leads to the creation of a stable fusion pore passing through the two membranes and which gives a constant release flux of neurotransmitter (pore-release stage). After a few milliseconds, this initial stage which is not investigated here proceeds through a sudden enlargement of the initial pore (full-fusion stage) up to the complete incorporation of the vesicle membrane into that of the cell and total exposure of the initial matrix vesicle core to the extracellular fluid. The precise time-resolved dynamics of the release and of the vesicle membrane during the full-fusion phase can be extracted with a precision never achieved so far by de-convolution of experimental chronoamperometric currents monitored during individual exocytotic secretion events. The peculiar dynamics of the vesicle membrane proves that exocytotic events are powered by the swelling of the matrix polyelectrolyte core of the vesicle, although they are kinetically regulated by diffusion in the matrix and by the dynamics of the vesicle and cell membranes. Two simple theoretical models based on the dynamics of pores are developed to account for these dynamics and are shown to predict behaviors which are essentially identical to the experimental ones. This offers a new view of the kinetic grounds which control the full-fusion stage, and therefore provides a new interpretation of the sudden transition between the pore-release and the full-fusion stages. This transition occurs when the increasing membrane surface tension energy due to the refrained internal swelling pressure overcomes the edge energy of the pore, so that the initial fusion pore becomes unstable and is disrupted. This new view predicts that secretory vesicles which contain matrixes energetically similar to those of the adrenal cells investigated here can be separated into two classes according to their radius and catecholamine content. Small vesicles (less than ca. 25 nm radius, and containing less than ca. 20000 molecules) should always release through pores. Larger vesicles should always end into fusing except if another mechanism closes the pore before ca. 10000 molecules of catecholamines have been released.
Animals↗
The interplay between covalent and non-covalent regulation of glycogen phosphorylase. The role of different effectors of phosphorylase b on the phosphorylase b to a conversion rate.
Glycogen phosphorylase b is converted to glycogen phosphorylase a, the covalently activated form of the enzyme, by phosphorylase kinase. Glc-6-P, which is an allosteric inhibitor of phosphorylase b, and glycogen, which is a substrate of this enzyme, are already known to have respectively an inhibiting and activating effect upon the rate of conversion from phosphorylase b to phosphorylase a by phosphorylase kinase. In the former case, this effect is due to the binding of glucose-6-phosphate to glycogen phosphorylase b. In order to investigate whether or not the rate of conversion of glycogen phosphorylase b to phosphorylase a depends on the conformational state of the b substrate, we have tested the action of the most specific effectors of glycogen phosphorylase b activity upon the rate of conversion from phosphorylase b to phosphorylase a at 0 degrees C and 22 degrees C : AMP and other strong activators, IMP and weak activators, Glc-6-P, glycogen. Glc-1-P and phosphate. AMP and strong activators have a very important inhibitory effect at low temperature, but not at room temperature, whereas the weak activators have always a very weak, if even existing, inhibitory effect at both temperatures. We confirmed the very strong inhibiting effect of Glc-6-P at both temperatures, and the strong activating effect of glycogen. We have shown that phosphate has a very strong inhibitory effect, whereas Glc-1-P has an activating effect only at room temperature and at non-physiological concentrations. The concomitant effects of substrates and nucleotides have also been studied. The observed effects of all these ligands may be either direct ones on phosphorylase kinase, or indirect ones, the ligand modifying the conformation of phosphorylase b and its interaction with phosphorylase kinase. Since we have no control experiments with a peptidic fragment of phosphorylase b, the interpretation of our results remains putative. However, the differential effects observed with different nucleotides are in agreement with the simple conformational scheme proposed earlier. Therefore, it is suggested that phosphorylase kinase recognizes differently the different conformations of glycogen phosphorylase b. In agreement with such an explanation, it is shown that the inhibiting effect of AMP is mediated by a slow isomerisation which has been previously ascribed to a quaternary conformational change of glycogen phosphorylase b. The results presented here (in particular, the important effect of glycogen and phosphate) are also discussed in correlation with the physiological role of the different ligands as regulatory signals in the in vivo situation where phosphorylase is inserted into the glycogen particle.
Adenosine Monophosphate↗
Functional characterisation of Eskimo dog hemoglobin: II. The interplay of HCO(3)- and Cl-.
Hemoglobin (Hb) from the Eskimo dog (belonging to Canis lupus familiaris) showed similar Bohr effect (delta log P50/delta pH) to human HbA in the presence of 100 mmol l-1 NaCl at 20 degrees C. The presence of 7% carbon dioxide in the desalted condition caused a positive (reversed) Bohr effect in the pH range 7.1-7.5 on Eskimo dog Hb, whereas in human HbA there was no Bohr effect within this pH range. A positive Bohr effect on Eskimo dog Hb in this condition was also observed at 37 degrees C. This could indicate differences in the pK values of the amino terminal residues of the two hemoglobins, with possible pH-dependent binding of both bicarbonate (HCO(3)-) and carbamate. Analysis of the effect of CO2 on oxygen affinity of Eskimo dog Hb in the pH range 6.7-7.6 in the presence of chloride and/or 2,3-diphosphoglycerate (2,3-DPG) support this theory. Our results indicate a competition between HCO(3)- and Cl- in affecting oxygen binding. Thermodynamic analysis reveals that bicarbonate binding lowers the apparent heat of oxygenation in Eskimo dog Hb nearly as much as chloride does in the presence of 2,3-DPG at physiological pH. This safeguards an effective oxygen unloading at lowered red blood cell concentrations of chloride. Moreover, we show that the oxygen affinity at high O2 saturation is less dependent on temperature in the presence than in the absence of CO2-.
Animals↗
Growth factors and steroid hormones: a complex interplay in the hypothalamic control of reproductive functions.
The mechanisms through which LHRH-secreting neurons are controlled still represent a crucial and debated field of research in the neuroendocrine control of reproduction. In the present review, we have specifically considered two potential signals reaching these hypothalamic neurons: steroid hormones and growth factors. Examples of the relevant physiological role of the interactions between these two families of biologically acting molecules have been provided. In many cases, these interactions occur at the level of hypothalamic astrocytes, which are presently accepted as functional partners of the LHRH-secreting neurons. On the basis of the observations here summarized, we have formulated the hypothesis that a functional co-operation of steroid hormones and growth factors occurring in the hypothalamic astrocytic compartment represents a key factor in the neuroendocrine control of reproductive functions.
Animals↗
A study on the interplay between energy and matter transformation: the effect of elevated temperatures on the leaf morphology of Vitis vinifera var. Merlot.
This investigation explores the relationship between increased energy levels and leaf morphology. It tests the idea that the causal agent of development is the dissipation of energy into transformed matter. The energy under which leaves developed was modified by increasing temperatures in grape cordons through wrapping them in clear plastic sleeves in the early spring. At the higher temperatures, and energy levels, there was a small but statistically significant decrease in leaf size and a change in organization the leaves. The decrease in leaf size may be due to a reallocation of resources, either to greater shoot growth as a previous study demonstrated or to the appearance of more vectors of development in the leaves, i.e. the appearance of more developmental subsystems. The leaves that grew under the higher temperature regime were more complex, perhaps indicating that the grapes on those same vines may produce more complex juice, another expression of more developmental subsystems. The change in organization in these leaves that developed at higher temperature argues that the causal agent in plant development is energy dissipation and the concomitant transformation of matter, the latter expressed in the appearance of more growth vectors.
Plant Leaves↗
The interplay between theta and alpha oscillations in the human electroencephalogram reflects the transfer of information between memory systems.
The exchange of information between the working and long-term memory system (WMS and LTMS) was investigated. We analyzed evoked theta and upper alpha desynchronization in a special memory task, designed to study the transfer of information between both memory systems. The results show that during attempts to retrieve information from the LTMS, evoked theta oscillations spread from anterior to posterior recording sites. When information actually is retrieved, the direction reverses and theta spreads to frontal sites. This time point--when direction reverses--varies between subjects to a large extent but is significantly correlated with memory performance and the onset of upper alpha desynchronization. We conclude that this phenomenon reflects the transfer of information between the WMS and LTMS
Adult↗
Pyretic and antipyretic signals within and without fever: a possible interplay.
Current concepts on the pathogenesis of fever emphasize the importance of the cytokine-prostaglandin cascade. This humoral line mediates nonthermal signals to the brain, while the thermal signals supply feedback from the thermoreceptors. However, the humoral line cannot alone account for the whole febrile response. Here, we hypothesize that, besides this humoral mediatory mechanism, nonthermal neural signals of abdominal origin conveyed mainly by the vagus nerve are also important pro-pyretic factors. The pro-pyretic mechanisms are proposed to be in a dynamic balance with endogenous antipyretic mechanisms that also form an integral part of the normal reaction to pyrogens. Further, it is hypothesized that the role of such neural and humoral signals either for elevation or depression of body temperature is not limited to fever but has an important role also in nonfebrile thermoregulation.
Analgesics, Non-Narcotic↗
An interplay of Sp1, GKLF and CREB-2 controls human Pre-alpha-Inhibitor gene (ITIH3) transcription.
Pre-alpha-Inhibitor is a plasma protease inhibitor and a heterodimeric molecule whose one polypeptide chain is encoded by the ITIH3 gene. In order to understand the expression of this protein that is regulated in health and disease, we have analyzed the 5' flanking region of ITIH3, specifically focussing on its proximal promoter. A combination of methods including wild-type (wt) or mutant promoter linked to a reporter cat gene, co-transfections of cat constructs with expression plasmids for nuclear factors and electrophoretic mobility shift assays revealed that two antagonistic sets of regulatory elements and nuclear proteins are critical for the activity of this promoter. Indeed, several overlapping Sp1/Sp3-binding sites are required for a sustained activity. However, a tripartite complex including CREB-2 and two molecules of the gut-enriched, Krüppel-like factor cooperate to bind to an upstream area whose 3' end overlaps the Sp1-binding sites. The resulting competition between this tripartite complex and Sp1 results in impaired occupancy of Sp1-binding sites by Sp1 and a consequent reduction in ITIH3 transcription. Competition between Sp1 and a Krüppel-like factor for GC-rich sites has been previously reported, but this is the first description of an elaborate tripartite cooperation of two Krüppel-like factors and CREB as a key step in such a competition.
Activating Transcription Factor 4↗
The NMR microimaging studies of the interplay of mass transport and chemical reaction in porous media.
PFG NMR is employed to perform a comparative study of the filtration of water and propane through model porous media. It is shown that the dispersion coefficients for water are dominated by the holdup effects even in a bed of nonporous glass beads. It is demonstrated that correlation experiments such as VEXSY are applicable to gas flow despite the large diffusivity values of gases. The PFG NMR technique is applied to study the gravity driven flow of liquid-containing fine solid particles through a porous bed. The NMR imaging technique is employed to visualize the propagation of autocatalytic waves for the Belousov-Zhabotinsky reaction which is carried out in a model porous medium. It is demonstrated that the wave propagation velocity decreases as the wave crosses the boundary between the bulk liquid and the flooded bead pack. The images detected during the catalytic hydrogenation of alpha-methylstyrene on a single catalyst pellet at elevated temperatures have revealed that the reaction and the accompanying phase transition alter the distribution of the liquid phase within the pellet.
Glass↗
Substance use disorder-PTSD comorbidity. Patients' perceptions of symptom interplay and treatment issues.
Forty-two patients with both a current substance use disorder (SUD) and posttraumatic stress disorder (PTSD) were asked about the interrelationship of their two disorders, their treatment preferences and experiences, as well as possible deterrents to receiving PTSD treatment. Patients perceived their two disorders to be functionally related. They reported that when one disorder worsened, their other disorder was more likely to worsen; when one disorder improved, the other disorder similarly improved. Consistent with these perceptions, SUD-PTSD patients favored simultaneous treatment of their two disorders. The majority of SUD-PTSD patients were never referred to PTSD treatment. Although several possible deterrents to PTSD treatment were identified, only lack of trust appeared to differentiate PTSD treatment compliers versus noncompliers. Implications of these findings on referral and treatment practices are discussed.
Adolescent↗
Repair of 8-oxoguanine in Saccharomyces cerevisiae: interplay of DNA repair and replication mechanisms.
8-Oxo-7,8-dihydroguanine (8-oxoG) is produced abundantly in DNA exposed to free radicals and reactive oxygen species. The biological relevance of 8-oxoG has been unveiled by the study of two mutator genes in Escherichia coli, fpg, and mutY. Both genes code for DNA N-glycosylases that cooperate to prevent the mutagenic effects of 8-oxoG in DNA. In Saccharomyces cerevisiae, the OGG1 gene encodes a DNA N-glycosylase/AP lyase, which is the functional homologue of the bacterial fpg gene product. The inactivation of OGG1 in yeast creates a mutator phenotype that is specific for the generation of GC to TA transversions. In yeast, nucleotide excision repair (NER) also contributes to the release of 8-oxoG in damaged DNA. Furthermore, mismatch repair (MMR) mediated by MSH2/MSH6/MLH1 plays a major role in the prevention of the mutagenic effect of 8-oxoG. Indeed, MMR acts as the functional homologue of the MutY protein of E. coli, excising the adenine incorporated opposite 8-oxoG. Finally, the efficient and accurate replication of 8-oxoG by the yeast DNA polymerase eta also prevents 8-oxoG-induced mutagenesis. The aim of this review is to summarize recent literature dealing with the replication and repair of 8-oxoG in Saccharomyces cerevisiae, which can be used as a paradigm for DNA repair in eukaryotes.
8-Hydroxy-2'-Deoxyguanosine↗
An interplay between two EGF-receptor ligands, Vein and Spitz, is required for the formation of a subset of muscle precursors in Drosophila.
Activation of the Drosophila EGF-receptor (DER) is spatially and temporally controlled by the release of its various ligands. DER and its ligand Spitz mediate the formation of specific somatic muscle precursors. We show that a second DER ligand, Vein, complements the activity of Spitz in the development of various somatic muscle precursors. In vn mutant embryos, the DER-dependent muscle precursors do not form in some of the segments. This phenotype is significantly enhanced in embryos carrying only one copy of wild type spitz. Our analysis suggests that Vein activation of DER differs qualitatively from that of Spitz in that it does not lead to the expression of the inhibitory protein Argos, possibly leading to a continuous activation of the DER signaling pathway.
Animals↗
Food intake and gastrointestinal motility. A complex interplay.
The complex network between the central nervous system and the enteric nervous system plays a pivotal role in preparing the digestive tract to receive food, process it to activate digestion and control food intake itself. This field has always stimulated researchers and is now receiving notable impetus by the availability of sophisticated technologies able to provide an increasing amount of complex data. This article describes recent findings that underline the role of feeding and the gastrointestinal system in regulating food intake.
Digestion↗
Face off--the interplay between activating and inhibitory immune receptors.
The function of leukocytes is regulated by the integration of positive and negative signals received through cell surface receptors. Related receptors with similar extracellular domains and often binding the same ligands can transmit either inhibitory or activating signals. Studies are beginning to reveal how these 'paired receptors' control immune functions.
Animals↗
Interplay between two epigenetic marks. DNA methylation and histone H3 lysine 9 methylation.
BACKGROUND: The heterochromatin of many eukaryotes is marked by both DNA methylation and histone H3 lysine 9 (H3-K9) methylation, though the exact relationship between these epigenetic modifications is unknown. In Neurospora, H3-K9 methylation is required for the maintenance of all known DNA methylation. In Arabidopsis, H3-K9 methylation directs some of the CpNpG and asymmetric methylation. However, it is not known in any organism whether DNA methylation may also direct histone H3 methylation. RESULTS: Using chromatin immunoprecipitation (ChIP) assays, we show that Arabidopsis heterochromatin is associated with H3-K9 methylation. This histone methylation is dependent on the KRYPTONITE and DDM1 genes (SU[VAR]3-9 and SWI2/SNF2 homologs, respectively). We also find that a decrease in DNA methylation does not directly cause a loss of H3-K9 methylation. Instead, a decrease in H3-K9 methylation is only seen at loci where transcription is derepressed. CONCLUSIONS: We conclude that DNA methylation does not control the methylation of histone H3-K9. We propose that loss of H3-K9 methylation is due to transcriptional reactivation, coupled with deposition of unmethylated nucleosomes. These findings are consistent with recent observations of DNA replication-independent deposition of histone H3.3 in Drosophila. Our results also suggest that, in Arabidopsis, DNA methylation is sufficient for gene silencing, but H3-K9 methylation is not.
Arabidopsis↗