Initial Phase Of Response Research Articles

A Study of High-Altitude Hypoxia-Induced Cell Stress in Murine Model

We evaluated the effects of high-altitude hypoxic stress in the murine model. For this purpose, 36 CR-mice in group A were maintained at the altitude of 3,820 m for hypoxia-induced factor (HIF)-1α expression analysis by immunohistochemistry. The 36 Wistar rats in group B were maintained in low-pressure (400-420 kPa) oxygen chamber, and the effects of hypoxia on myocardial mitochondria were studied. In the 36 CR-mice of group C, plasma vascular endothelial growth factor (VEGF) levels were determined using strept-avidin-biotin complex/diaminobenzidine method after exposure to different altitudes/O(2)-concentrations. The data show that in experimental group A1, endothelin (ET)-1α concentrations gradually increased whereas HIF-1α expression in myocardial cells was higher (P < 0.01) than in control group A2. In rats of group B, the myocardial mitochondria numbers were reduced during the initial phase of acute stress response to hypoxia and cellular injury but, later, mitochondrial numbers were restored to normal values. In mice of experimental group C1, plasma VEGF concentrations increased under hypoxia, which were significantly higher (P < 0.01) than those of control group C2. We, therefore, concluded that high-altitude hypoxia: (i) induced HIF-1α expression; (ii) prompted adaptation/acclimatization after initial stress and cellular injury; and (iii) enhanced VEGF expression in murine.

Behaviour of human physeal chondro-progenitorcells in early growth plate injury response in vitro

The aim of this study was to investigate the proliferation and differentiation behaviour of a defined cell population gained from the human growth plate, namely, chondro-progenitorcells (CPCs), in the initial inflammatory phase of growth plate injury response in vitro. Growth plate cells were sorted via FACS and differentiated along adipogenic and osteogenic lineage to confirm their progenitor features. To mimic the inflammatory phase of injury response at the growth plate they were treated with IL-1β and exposed to cyclic mechanical loading. A BrdU assay was used to investigate CPC proliferation. CPC differentiation behaviour was analysed by RT-PCR. CPCs (CD45-, CD34-, CD73+, CD90+, and CD105+) showed a successful differentiation along adipogenic and osteogenic lineage. Under conditions simulating the inflammatory phase of injury response at the growth plate in vitro CPCs differentiated towards hypertrophy while chondrogenesis and ossification were inhibited. Proliferation was not significantly altered. This study showed that CPCs can be isolated from the human growth plate and expanded in vitro. In the first phase of injury response at the growth plate these cells differentiate towards hypertrophy. As longitudinal growth is obtained by chondrocyte proliferation and volume increase during hypertrophy this maturation might be the first step towards post-traumatic growth disorders such as unwanted premature ossification of the growth plate.

Peripheral tolerance induced by apoptotic cells and PD-1+ CD8 T cells

Self tolerization in peripheral is critical to prevent autoimmune diseases including arthritis and here we focus on the role of PD-1 in tolerance induction against the antigen associated with apoptotic cellsdelivered intravenously (i.v.). We accessed delayed type hypersensitivity (DTH) reaction against hapten (TNP) as antigen specific immune response, in which the injection of TNP-apoptotic cells i.v. suppressed DTH in wild type mice but we found not in PD-1 KO mice (Figure ​(Figure1).1). Adaptive transfer of CD8 T cells into PD-1 KO mouse from wild type mice tolerated with TNP-apoptotic cells suppresses DTH. This result shows PD-1 functions on CD8 T cells for immune suppression. Additionally we neutralized the PD-1 with antibody to determine the phase when PD-1 functions for immune tolerance by apoptotic cells, and identified PD-1 functions particularly at the initial phase of antigen specific immune response. We are further studying the mechanism of suppressive role of PD-1+ CD8 T cells that should be activated with apoptotic cells. Figure 1 PD-1 is essential for tolerance induced by apoptotic cells. TNP-apoptotic cells were injected intravenously into PD-1 hetero- or homo- deficient mice. The mice were immunized with TNP (Filled bar) or preconditioned with apoptotic cells before immunization ...

A Civilian Reporting Service to Guide Converging Resources for Search and Rescue in Disaster Response

During disaster response, prioritization of limited resources is one of the most important but challenging tasks. At the same time, it is imperative to timely provide to the rescuers with the adequate heavy equipment to facilitate lifesaving operations. However, supply of high demand equipment is usually insufficient during the initial phase of disaster response, challenging lifesaving operations. At the same time, resources outside of the disaster affected zone converge into the area to assist the response efforts, which is the effect of convergence that often made resource coordination challenging in large scale disasters. Meanwhile, the initial condition of the disaster is usually best known by civilians already at the area before and during impact of the disaster. The knowledge of the civilians is not always received and considered by the responding organizations. With the help of these civilians, critical information such as victim location, infrastructure damage, and risk condition could be better know before any response actions are taken. To efficiently collect information and utilize the converging resources, this paper proposes a geospatial information repository for initial condition reporting and update to guide search and rescue operations and deployment of equipment with safety considerations for the rescuers in large scale disaster response scenarios.

Pro-apoptotic and anti-inflammatory properties of the green tea constituent epigallocatechin gallate increase photodynamic therapy responsiveness

A polyphenol constituent of green tea, epigallocatechin gallate (EGCG), has anti-carcinogenic properties. A growing number of studies document EGCG-mediated induction of apoptotic pathways and inhibition of pro-survival factors when combined with chemotherapy or radiation. We evaluated the efficacy of EGCG in modulating photofrin (PH)-mediated photodynamic therapy (PDT) responses. Mouse mammary carcinoma (BA) cells and transplanted BA tumors growing in C3H mice were treated with PH-mediated PDT. Select groups of treated cells and mice also received EGCG and then cytotoxicity, tumor response, and expression of survival molecules were evaluated in all experimental groups. EGCG increased apoptosis and cytotoxicity in BA cells exposed to PH-mediated PDT. The initial pro-survival phase of the unfolded protein response (UPR), characterized by increased expression of the 78 kDa glucose-regulated protein (GRP-78), was induced by PDT. The second pro-apoptotic phase of the UPR, characterized by phospho-c-Jun N-terminal kinase (p-JNK) expression, activation of caspases-3 and 7, poly ADP ribose polymerase (PARP) cleavage, and expression of C/EBP homologous protein was observed when PDT was combined with EGCG. EGCG also decreased the expression of the pro-survival proteins GRP-78 and survivin, and attenuated PDT-induced prostaglandin E2 (PGE2 ) expression in PDT-treated cells. Comparable responses also were observed when BA tumors were treated with PDT and EGCG. In addition, PDT-induced expression of metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) was down-regulated in treated tumor tissue by EGCG. The polyphenol EGCG improves PDT efficacy by increasing tumor apoptosis and decreasing expression of pro-survival and angiogenic molecules within the tumor microenvironment.

Investigations on N-rich protein (NRP) of Arabidopsis thaliana under different stress conditions

Stress response and adaptation are important physiological mechanisms in plants. As plants are not able to avoid stressful environments by moving away, as animals, they have developed diverse mechanisms to respond to stressful situations. One of the genes involved in these mechanisms is NRP (Asparagine-rich protein or N-rich protein). In this study, NRP expression, protein localization and nrp knockout plants were investigated for further understanding of NRP function. NaCl-induced salt stress, oxidative stress (ozone exposure) and mechanical perturbation (touch treatment) were used to induce abiotic stress. NRP expression was up-regulated in the early phase of stress response to all three elicitors. Stressed nrp knockout seedlings revealed a more pronounced growth inhibition compared to wildtype (salt and osmotic stress). Seedlings showed NRP-GFP expression in the apical meristem, leaf veins, central cylinder, root hair zone and root tip. Analyses of NRP-GFP localization in root cells and protoplasts revealed cytosolic distribution under non-stress conditions and translocation of NRP-GFP to mitochondria due to stress response. Summarizing, our findings point to a contribution of NRP in signal transduction of the initial phase of general stress response in Arabidopsis thaliana.

Loss of H3 K79 Trimethylation Leads to Suppression of Rtt107-dependent DNA Damage Sensitivity through the Translesion Synthesis Pathway

Genomic integrity is maintained by the coordinated interaction of many DNA damage response pathways, including checkpoints, DNA repair processes, and cell cycle restart. In Saccharomyces cerevisiae, the BRCA1 C-terminal domain-containing protein Rtt107/Esc4 is required for restart of DNA replication after successful repair of DNA damage and for cellular resistance to DNA-damaging agents. Rtt107 and its interaction partner Slx4 are phosphorylated during the initial phase of DNA damage response by the checkpoint kinases Mec1 and Tel1. Because the natural chromatin template plays an important role during the DNA damage response, we tested whether chromatin modifications affected the requirement for Rtt107 and Slx4 during DNA damage repair. Here, we report that the sensitivity to DNA-damaging agents of rtt107Δ and slx4Δ mutants was rescued by inactivation of the chromatin regulatory pathway leading to H3 K79 trimethylation. Further analysis revealed that lack of Dot1, the H3 K79 methyltransferase, led to activation of the translesion synthesis pathway, thereby allowing the survival in the presence of DNA damage. The DNA damage-induced phosphorylation of Rtt107 and Slx4, which was mutually dependent, was not restored in the absence of Dot1. The antagonistic relationship between Rtt107 and Dot1 was specific for DNA damage-induced phenotypes, whereas the genomic instability caused by loss of Rtt107 was not rescued. These data revealed a multifaceted functional relationship between Rtt107 and Dot1 in the DNA damage response and maintenance of genome integrity.

The role of store-operated Ca 2+ channels in adrenocorticotropin release by rat pituitary cells

In this study, we investigated the role of store-operated Ca 2+ channels (SOCC) on ACTH release using microperifusion system. The SOCC blockers, SKF96365 and MRS1845, did not affect the ACTH response to single AVP stimulation. After the depletion of intracellular Ca 2+ stores by treating with ionomycin, SOCC blockers reduced the initial spike phase of ACTH response to AVP, which is mediated by inositol 1,4,5-trisphosphate-induced intracellular Ca 2+ release from the endoplasmic reticulum (ER). The sustained plateau phase of ACTH response, which is mediated by protein kinase C leading Ca 2+ influx via L-type voltage-dependent Ca 2+ channels, was not affected. Addition of L-type voltage-dependent Ca 2+ channel blocker nimodipine with the SOCC blockers reduced both the initial spike and sustained phases of ACTH response to AVP. Even after ER Ca 2+ depletion, the SOCC blockers did not affect the ACTH response to CRH, which is mediated by cAMP-dependent protein kinase A. Transient receptor potential (TRP) C channel is the strongest candidate for SOCC, and RT-PCR revealed that all types of TRPC homologue mRNA were expressed in rat anterior pituitary cells. In conclusion, the SOCC mediates the initial spike phase of ACTH response to AVP, possibly via ER Ca 2+ store refilling to induce maximum response.

Identification of an apoplastic protein involved in the initial phase of salt stress response in rice root by two-dimensional electrophoresis.

The apoplast of plant cells, which carries out multiple functions in plant metabolism and signaling, is not only a barrier but also the linker between the environment and the protoplast. To investigate the role of apoplastic proteins in the salt stress response, 10-d-old rice (Oryza sativa) plants were treated with 200 mM NaCl for 1, 3, or 6 h, and the soluble apoplast proteins were extracted for differential analysis compared with untreated controls using two-dimensional electrophoresis. Ten protein spots that increased or decreased significantly in abundance were identified by mass spectrometry. These proteins included some well-known biotic and abiotic stress-related proteins. Among them, an apoplastic protein, with extracellular domain-like cysteine-rich motifs (DUF26), O. sativa root meander curling (OsRMC), has shown drastically increased abundance in response to salt stress during the initial phase. OsRMC RNA interference transgenic rice has been generated to assess the function of OsRMC in the salt stress response. The results show that knocking down the expression level of OsRMC in transgenic rice led to insensitive seed germination, enhanced growth inhibition, and improved salt stress tolerance to NaCl than in untransgenic plants. These results indicate that plant apoplastic proteins may have important roles in the plant salt stress response.

Neonatal caffeine induces sex-specific developmental plasticity of the hypoxic respiratory chemoreflex in adult rats

Caffeine is widely used to treat apneas of prematurity during the neonatal period; however, the potential consequences of administering a neonatal caffeine treatment (NCT) during a critical period for respiratory control development are unknown. The present study therefore determined whether NCT in rats alters the hypoxic respiratory chemoreflex measured at adulthood. Newborn rats received either caffeine (15 mg/kg) or water (control) each day from postnatal day 3 to 12. The ventilatory response to a hypoxic challenge (inspired O(2) fraction = 0.12) was first evaluated in awake adult female and male rats using whole body plethysmography. Results showed that NCT increased the initial phase of the breathing frequency response to hypoxia in males only. This result was confirmed in anesthetized and artificially ventilated adult male rats where NCT also increased the phrenic burst frequency response to hypoxia. RT-PCR assessment of mRNA encoding for adenosine A(1A) and A(2A) receptors, dopamine D(2) receptors, and tyrosine hydroxylase in the rat carotid bodies showed that NCT enhanced mRNA expression levels of adenosine A(2A), dopamine D(2) receptors, and tyrosine hydroxylase of males but not females. Subsequent experiments on awake male rats showed that injection of the adenosine A(2A) receptor antagonist ZM2413855 (1 mg/kg ip) before ventilatory measurements abolished, in NCT rats, the enhanced respiratory frequency response observed during the early phase of hypoxia. We propose that NCT elicits a sex-specific increase in the hypoxic respiratory chemoreflex, which is related, at least partially, to an enhancement in adenosine A(2A) receptors in the rat carotid body.

Immunosuppressive effect of cyclosporin A on insect humoral immune response

Cyclosporin A suppressed humoral immune response of Galleria mellonella larvae. Insects were immunized with LPS Pseudomonas aeruginosa and then injected with cyclosporin A. Immunosuppressive effects were expressed both, in larvae treated with cyclosporin A at the initial phase of immune response and at the effector phase of antibacterial immunity. Cyclosporin A moderately decreased lysozyme activity and significantly decreased antibacterial activity peptides against Escherichia coli. Immunosuppressive effects of cyclosporin A were observed after immunoblotting with antibodies anti- G. mellonella lysozyme. Tricine SDS/PAGE shown that synthesis of antibacterial peptides of larvae treated with cyclosporin A was considerably inhibited. Insects of impaired immune response by cyclosporin A action lost protective immunity to insect bacterial pathogen P. aeruginosa.

Effect of short-term peroral administration of synthetic trypsin inhibitor on endocrine secretion in the isolated perfused rat pancreas.

The effects of peroral treatment with synthetic trypsin inhibitor on endocrine secretion in response to four different stimuli were investigated in the isolated perfused rat pancreas. After 10 days' treatment pancreatic wet weights and protein and amylase contents in the pancreas were significantly increased. On the other hand, total contents of IRI and IRG in the T.I.-treated and control pancreas were nearly the same. In spite of the lack of alteration in hormone contents, a lower initial phase of IRI response to 8.3 mM glucose, glucose plus 0.1 ng/ml caerulein or 20 mM arginine was observed in the T.I.-treated pancreas. Furthermore, the IRI response to 10 mM theophylline was both slower and the most reduced in the T.I.-treated pancreas. From these observations, it is suggested that short-term peroral administration of synthetic trypsin inhibitor not only has no trophic effect on pancreatic B-cell and A-cell in the rat but also may affect some pathway of insulin secretion from the B-cell to reduce IRI responses to secretagogues.

Does the understanding of immune activation by RNA predict the design of safe siRNAs?

The innate immune system uses pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) to recognize conserved pathogen-associated molecular patterns (PAMPs) expressed by microbes and to activate the initial phase of immune response. Both bacterial and viral nucleic acids activate TLRs resulting in cytokines and interferon production. Recent studies indicated that unmodified small interfering RNAs (siRNAs) corresponding to either mammalian (self) or microbial (non-self) RNA sequences can activate immunity through TLR7/8 in a sequence-dependent manner. Hence, the use siRNAs in humans will require understanding the mechanisms involved in the discrimination between self and non-self RNAs. In the case where immunostimulation is not wanted, chemical modifications can prevent immune activation and reduce off-target effects, while preserving siRNA silencing potency. Interestingly, 2'-O-methyl modified RNAs not only evade immune sensing, but antagonize with immunostimulatory single- or double-stranded siRNAs to activate innate immunity. This review highlights the recent progress in understanding the siRNA sensing by innate immunity and presents a range of strategies allowing either the design of siRNAs with minimal or maximal immunostimulatory potency for therapeutic applications.

The fate of effector CD8 T cells in vivo is controlled by the duration of antigen stimulation

What controls the fate of the T-cell response remains incompletely defined. Gain of effector function facilitated by costimulation has been thought to be a crucial factor in determining the outcome of the T-cell response, i.e. long-term memory in the presence of costimulation versus tolerance induction in the absence of costimulation. In this study, we show that while costimulation or cognate CD4 helps to promote the acquisition of effector function during the initial phase of the CD8 T-cell response, the fate of effector CD8 T cells is controlled by the duration of subsequent antigenic stimulation. Effector CD8 T cells differentiate into memory cells only after clearance of antigen, whereas in the presence of persistent antigen, effector CD8 T cells are tolerized. Furthermore, protective immunity against tumour cannot develop in the persisting antigen environment. These results suggest that removal of persisting antigen by other means might be a prerequisite for effective immunotherapy in cancer.

Human milk oligosaccharides affect P-selectin binding capacities: In vitro investigation

Objective In the initial phase of cellular immune response, selectins mediate the emigration of leukocytes from the blood stream into inflammatory regions. Human milk oligosaccharides (HMOs) possess binding epitopes of selectin ligands such as sialyl Lewis x and sialyl Lewis a and therefore might impair the interaction of selectins with cellular ligands. Neutral, acidic, sialylated, or fucosylated HMO fractions with polymerization degrees of 3 to 50 were investigated regarding this interaction in a dynamic flow chamber model that considers physiologic shear stress conditions. Methods Human milk oligosaccharides were compared with κ-carrageenans and pectin oligosaccharides to deduce structure-activity relations. Fucoidan and sialyl Lewis x served as positive controls. Results All HMO fractions affected P-selectin ligand binding capacity but were not comparable to fucoidan. The activity of the acidic HMO fraction resembled sialyl Lewis x in decreasing the binding of the ligand to P-selectin. Conclusion Human milk oligosaccharides modulate rather than block the function of P-selectin.

Contribution of lipid second messengers to the regulation of phosphatidylcholine synthesis during cell cycle re-entry

During entry into the cell cycle a phosphatidylcholine (PC) metabolic cycle is activated. We have examined the hypothesis that PC synthesis during the G 0 to G 1 transition is controlled by one or more lipid products of PC turnover acting directly on the rate-limiting enzyme in the synthesis pathway, CTP: phosphocholine cytidylyltransferase (CCT). The acceleration of PC synthesis was two- to threefold during the first hour after addition of serum to quiescent IIC9 fibroblasts. The rate increased to ∼15-fold above the basal rate during the second hour. The production of arachidonic acid, diacylglycerol (DAG), and phosphatidic acid (PA) preceded the second, rapid phase of PC synthesis. However, an increase in the cellular content of these lipid mediators was detected only for DAG. CCT activation and translocation to membranes accompanied the second phase of the PC synthesis acceleration. Bromoenol lactone (BEL), an inhibitor of calcium-independent phospholipase A 2 and PA phosphatase, blocked production of fatty acids and DAG, inhibited both phases of the PC synthesis response to serum, and reduced CCT activity and membrane affinity. The effect of BEL on PC synthesis was partially reversed by in situ generation of DAG via exogenous PC-specific phospholipase C to generate ∼2-fold elevation in PC-derived DAG. Exogenous arachidonic acid also partially reversed the inhibition by BEL, but only at a concentration that generated a supra-physiological cellular content of free fatty acid. 1-Butanol, which blocks PA production, had no effect on DAG generation, or on PC synthesis. We conclude that fatty acids and DAG could contribute to the initial slow phase of the PC synthesis response. DAG is the most likely lipid regulator of CCT activity and the rapid phase of PC synthesis. However, processes other than direct activation of CCT by lipid mediators likely contribute to the highly accelerated phase during entry into the cell cycle.

Possible mechanisms of action of the neutral extract from Bidens pilosa L. leaves on the cardiovascular system of anaesthetized rats.

The aim of this study was to investigate the hypotensive and cardiac effects of the neutral extract from Bidens pilosa leaves. Intravenous administration of the extract resulted in a biphasic dose-related hypotensive activity. In normotensive rats (NTR), B. pilosa decreased systolic blood pressure by 18.26%, 42.5% and 30% at doses of 10, 20 and 30 mg/kg, respectively. In spontaneously hypertensive rats (SHR), the decrease in systolic blood pressure was 25.77%, 38.96% and 28.64% at the above doses, respectively. These doses induced hypotension by 27%, 34.13% and 18.73% respectively in salt-loaded hypertensive rats. In NTR, B. pilosa reduced heart rate by 23.68% and 61.18% at doses of 20 and 30 mg/kg, respectively. The force of contraction of the heart was only affected at 30 mg/kg. The initial phase of hypotensive response was partially inhibited by atropine while propranolol increased this effect. These results suggest that B. pilosa exhibited its fi rst hypotensive effects by acting on the cardiac pump efficiency and secondly through vasodilation.

Psoralen and UVA Light: An in Vitro Investigation of Multiple Immunological Mechanisms Underlying the Immunosuppression Induction in Allograft Rejection

ABSTRACT Photopheresis (ECP) is a novel immunomodulatory therapy effectively used to treat several T-cell-mediated diseases and to reverse allograft rejection after organ transplantation. It consists of infusion of UVA-irradiated autologous leukocytes collected by apheresis and extracorporeally incubated with 8-methoxypsoralen (8-MOP). In this study we explored the potential immunological events for therapeutic efficacy of photopheresis in preventing allograft rejection by evaluating in vitro the combined effects of 8-MOP and UVA (PUVA) on multiple immunological parameters, such as induction of apoptosis, production of soluble mediators, and expression of cell antigens. Peripheral blood mononuclear cells (PBMCs) obtained from healthy subjects were treated with 8-MOP and UVA at the same doses as those clinically used in ECP. We demonstrate that PUVA treatment induced leukocyte hyporesponsiveness and a decrease in expression of co-stimulatory and adhesion molecules as well as of cytokine levels. Additionally, PUVA treatment induced apoptosis in both mononuclear cells (possibly through the Fas/FasL system and/or the CD38 pathway) and purified monocytes. In conclusion, our work focuses attention on the initial phase of immune response and identifies some new targets of therapy (e.g., costimulatory molecules) able to trigger final effects underlying therapeutic efficacy of photopheresis.

Evaluation of order and the spread of time constants for aperiodic processes using step response

A simple and effective method of parameter identification for a linear model of aperiodic processes with known time delay is presented in this paper. The process time lag order and, subsequently, the remaining model parameters are determined from a few samples of the initial phase of the process step response. The method enables one to evaluate tha gain and the mean time constant (whenusing Strejc.s model), as well as the spread of time constants and, subsequently, the individual time constants over the range (T min, T max) (when using the multi-time-lag model with different time constants. Test results regarding the identification of selected electroheated control plants, as well those regarding the autotuning of PID controllers, are given.

Erythrodynamics in fish: recovery of the goldfishCarassius auratusfrom acute anemia

Goldfish (Carassius auratus) were rendered anemic through immersion in phenylhydrazine∙HCl, a cohort of [3H]thymidine-labelled erythrocytes was established, and recovery followed over a 234-d period. Red blood cell (RBC), hemoglobin (Hb), and hematocrit (Hct) levels increased in biphasic fashion during recovery, rapid increases to plateau values being followed by more modest increases to levels equalling those observed prior to treatment. During the initial rapid phase of response, increased ventilatory and cardiovascular activities probably compensated for deficits in oxygen-carrying capacity but, by elevating blood O2tension, may have suppressed erythropoiesis. Continuing slow increases in RBC, Hb, and Hct may point to some as yet unidentified alternative mechanism for stimulating red cell formation. During maturation, mean erythrocytic volume decreased, while mean erythrocytic hemoglobin level increased. Cycles of division of circulating juvenile erythrocytes occurred at roughly 56-d intervals, but did not appear to play a major role in elevating blood O2-carrying capacity. Division and karyorrhexis or cell breakdown were loosely correlated. Under the conditions employed, red cell half-life was approximately 80 d.