Chemical Stimulators Research Articles

L-2L ladder digital-to-analogue converter for dynamics generation of chemical concentrations.

Cellular response to dynamic chemical stimulation encodes rich information about the underlying reaction pathways and their kinetics. Microfluidic chemical stimulators play a key role in generating dynamic concentration waveforms by mixing several aqueous solutions. In this article, we propose a multi-layer microfluidic chemical stimulator capable of modulating chemical concentrations by a simple binary logic based on the electronic-hydraulic analogy of electronic R-2R ladder circuits. The proposed device, which we call L-2L ladder digital-to-analogue converter (DAC), allows us to systematically modulate 2 n levels of concentrations from single sources of solution and solvent by a single operation of 2n membrane valves, which contrasts with existing devices that require complex channel geometry with multiple input sources and valve operations. We fabricated the L-2L ladder DAC with n = 3 bit resolution and verified the concept by comparing the generated waveforms with computational simulations. The response time of the proposed DAC was within the order of seconds because of its simple operation logic of membrane valves. Furthermore, detailed analysis of the waveforms revealed that the transient concentration can be systematically predicted by a simple addition of the transient waveforms of 2n = 6 base patterns, enabling facile optimization of the channel geometry to fine-tune the output waveforms.

Exploration and characterization of chemical stimulators to maximize the wax ester production by Euglena gracilis

Euglena gracilis, a phototrophic protist, is a valuable biomass producer that is often employed in sustainable development efforts. E.gracilis accumulates wax esters as byproducts during anaerobic ATP production via the reductive tricarboxylic acid cycle, utilizing the storage carbohydrate β-1,3-glucan paramylon as the carbon source. Here, we report a library screening for chemical stimulators that accelerate both wax ester production and paramylon consumption. Among the 115 compounds tested, we identified nine compounds that increased wax ester production by more than 2.0-fold relative to the solvent control. In the presence of these nine compounds, the paramylon content decreased compared with the control experiment, and the residual paramylon content varied between 7% and 26% of the initial level. The most active compound, 1,4-diaminoanthracene-9,10-dione (OATQ008), stimulated wax ester production up to 2.7-fold within 24h, and 93% of the cellular paramylon was consumed. In terms of the structural features of the chemical stimulators, we discuss the potential target sites to stimulate wax ester production in mitochondria under anaerobic conditions.

Patients- and tissue-specific bio-inks with photoactivated PRP and methacrylated gelatin for the fabrication of osteochondral constructs

In osteochondral tissue engineering, while the biochemical and mechanical properties of hydrogels guide stem cell proliferation and differentiation, physical and chemical stimulators also affect the differentiation of stem cells. Herein, we presented a patient and tissue-specific strategy for the development of biomimetic osteochondral constructs with gradient compositions. Osteochondral constructs were fabricated by gradually printing of bio-inks consisting of therapeutic platelet-rich plasma (PRP), adipose tissue-derived mesenchymal stem cells (AdMSCs), and extracellular matrix (ECM) mimetic hydrogel, microwave-assisted methacrylated gelatin (Gel-MA). Periodic application of light in the near infrared region (600–1200 nm wavelength) was used to induce platelet activation and also AdMSCs' differentiation. Gel-MA has the same structure as type I collagen and PRP has cartilage tissue-specific bioactive components, so they provide the appropriate environment for the differentiation of AdMSCs to osteochondral tissue. Histology, immunocytochemistry, and biochemical analyses indicated enhanced glycosaminoglycan (GAG) and calcium content, mineralization, and ECM production. Furthermore, RT-PCR results indicated the expressions of bone- and cartilage-specific genes. In conclusion, the periodically photoactivated hydrogels with relatively low degradation rate and high mechanical strength, and tissue-specific biomimetic structure promoted in-vitro osteochondral tissue formation including hyaline and hypertrophic cartilage and bone phases.

Methods for the discovery of small molecules to monitor and perturb the activity of the human proteasome.

Regulating protein production and degradation is critical to maintaining cellular homeostasis. The proteasome is a key player in keeping proteins at the proper levels. However, proteasome activity can be altered in certain disease states, such as blood cancers and neurodegenerative diseases. Cancers often exhibit enhanced proteasomal activity, as protein synthesis is increased in these cells compared with normal cells. Conversely, neurodegenerative diseases are characterized by protein accumulation, leading to reduced proteasome activity. As a result, the proteasome has emerged as a target for therapeutic intervention. The potential of the proteasome as a therapeutic target has come from studies involving chemical stimulators and inhibitors, and the development of a suite of assays and probes that can be used to monitor proteasome activity with purified enzyme and in live cells.

Bezold Jarisch Reflex- New Interest, Old Phenomenon

Bezold Jarisch reflex (BJR) is an eponym for a triad of responses namely: bradycardia, hypotension and vasodilation that develops upon stimulation of intracardiac mechanoreceptors and is mediated by vagal afferent nerve fibers. Though it was first reported in 1867 it remains a topic of discussion due to its implications in various clinical scenarios. The reflex can be stimulated either by mechanical or chemical stimulators. Often considered a physiologic response, if identified by the clinician at earlier phase, can avoid cardiac complication, it also acts as a prognostic indicator in various diseases. This review focuses on the physiology of the BJR and its possible physiologic role in several clinical situations. We used evidence obtained from a computerized literature of medical databases search using PubMed/Medline/NIH (all articles till October 2019). The search was carried out with MeSH phrase “Bezold Jarisch reflex” and articles were limited to English language only. The relevant published reports, abstracts and human studies with clinical cases to determine the clinical implications of BJR were considered for the review. It has been concluded that BJR is a physiologic response that can occur in number of clinical scenarios. Therefore, simultaneous occurrence of bradycardia and hypotension should alert clinicians to the possibility of BJR.

Gas-Sensing Properties of Thin Films Grown on the Surface of InP Single Crystals by Thermal Oxidation

Thin nanofilms have been grown on the surface of single-crystal InP wafers using PbO + V2O5 mixtures in the gas phase. The oxide mixtures used as chemical stimulators have been shown to accelerate the thermal oxidation of InP. The resultant films exhibit gas-sensing properties for ammonia (concentration of 140 ppm) and carbon monoxide (95 ppm). The highest gas sensitivity is near 1.2 arb. units, at temperatures in the range 200–240°C.

Biometric Indicators and Yield of Tomato under Conventional and Unconventional Biostimulators

The research consisted of an experiment applying unconventional stimulators to tomato crop, as a measure against chemical stimulators, known as having negative effects on human health. In our research there have been used four unconventional stimulators (Ecostim, AuCl4-50μg, AuCl4-30μg and Chitosan) and a conventional stimulator BNOA, all compared with the untreated control.Application of stimulators in unconventional farming determined lower productions compared to conventional farming, but is an alternative because determined healthy products. In three of the four unconventional variants, the content of macro- and microelements in plants was higher.

CHEMICAL AND BIOLOGICAL SEED TREATMENT AND THEIR EFFECT ON SOYBEAN DEVELOPMENT AND YIELD

ABSTRACT In the search for homogeneous planting density and satisfactory results in soybean development and yield, the treatment of seeds can be carried out using a combination of chemical fungicides, growth stimulators, and other biological agents. The objective of this study is to evaluate the effect of chemical and biological inputs for soybean seed treatment on crop development and yield. Experiments were carried out in the 2010/2011 growing season in three municipalities of Rio Grande do Sul using the following treatments: fungicide fludioxonil, Trichoderma spp., fludioxonil + Trichoderma spp., fludioxonil + Trichoderma spp. + the growth stimulator Biozyme®, and a control (untreated). The total number of pods in treatment with Trichoderma spp. and the other treatments were up to 77% higher than that of the control. The grain yield of treatments with fludioxonil, fludioxonil + Trichoderma spp., and fludioxonil + Trichoderma spp. + Biozyme® was up to 14% higher than that of the control. These results indicate that fludioxonil combined with the fungus Trichoderma spp. and Biozyme® is indicated for treating soybean seeds and increases crop development and grain yield.

Selection and Validation of Reference Genes for Gene Expression Studies by RT-PCR in Dalbergia odorifera

Perennial tree Dalbergia odorifera T. Chen could form the precious heartwood used to produce chinese traditional medicine, rosewood furniture and fragrances. However the formation of heartwood is time-consuming and low efficient, leading to the severe destruction of its wild resources. Thus, it is urgent to study the molecular mechanism of heartwood formation in D. odorifera. But till now, there is no report about the reference gene selection in this species. In this study, the expression stability of nine candidate reference genes were evaluated across different tissues and stems treated by wound and chemical stimulators. Four algorithms were applied to obtain the robust genes. The results support HIS2, GAPDH, and CYP to be the most stable reference genes in samples under different wound treatments while DNAj was the least stable. In different tissues, HIS2, UBQ, and RPL were the most stable reference genes while DNAj was the least stable. The selected reference genes were validated through the normalization of the qRT-PCR data of six heartwood related genes in terpene biosynthesis pathway and ethylene signal pathway. The results showed that their expression levels were accurate when they were normalized by the most stable reference gene HIS2, or by the combination of the two or three most stable reference genes. These results demonstrated that these selected reference genes are reliable.

Determination of EEG for smell sensitive brain’s areas by using chemical stimulators

The electroencephalogram (EEG) is a unique and valuable measure of the brain’s electrical functions. It is a graphic display of a difference in voltages from two sites of brain function recorded over time. Physical, chemical and mechanical stimulators appear as wave frequency, action potential amplitude changes which are reaching different areas in the brain. Each area is responsible to record a certain type of stimulator whether it is chemical that is received by smelling, and test senses, physical stimulator by hearing, , and vision senses, or touching stimulator. This research is concentrated on the determination of the most sensitive areas (the correct channels of electrodes placement system) of the brain that are responsible to receive the highest chemical stimulation due to the action of Lavender perfume stimulator (Lavender perfume with concentration of 50 % ), for normal males and females subjects for smelling sense. Ten males and the same numbers of females all subjects selected within the age range between (25- 30) years old. It has been found that T3 and T4 are the best channels connections for smelling sense for both male and female, and that the mean relative action potential (The ratio of action potential amplitude after to that before exposure of perfume stimulation) for males are higher than that for females, these results reflect that males are more sensitive than females in this type of perfume and may be it is not in other type, and the mean relative action potential amplitude for the channels T3, T4, T5, T6, P3, and P4 are 2.05, 1.80, 1.12, 1.20, 1.10, and 1.10 for males and 1.96, 1.76, 1.12, 1.11, 1.09, 1.09 for females respectively.

Chemically stimulated synthesis of gas-sensing films on the surface of GaAs

Thin nanofilms have been grown on the surface of GaAs via chemically stimulated thermal oxidation. The thickness of the oxide films on the surface of GaAs has been shown to be a nonlinear function of the composition of the mixture of the chemical oxide stimulators. The oxide films obtained, consisting predominantly of Ga2O3, contain small amounts (≤3 at %) of Sb2O3 and V2O5 and exhibit gas-sensing properties in ammonia and carbon monoxide atmospheres, with the highest NH3 sensitivity of 1.29 in the temperature range 200–240°C and the highest CO sensitivity of 1.26 in the range 180–220°C.

Po2 cycling protects diaphragm function during reoxygenation via ROS, Akt, ERK, and mitochondrial channels.

Po2 cycling, often referred to as intermittent hypoxia, involves exposing tissues to brief cycles of low oxygen environments immediately followed by hyperoxic conditions. After experiencing long-term hypoxia, muscle can be damaged during the subsequent reintroduction of oxygen, which leads to muscle dysfunction via reperfusion injury. The protective effect and mechanism behind Po2 cycling in skeletal muscle during reoxygenation have yet to be fully elucidated. We hypothesize that Po2 cycling effectively increases muscle fatigue resistance through reactive oxygen species (ROS), protein kinase B (Akt), extracellular signal-regulated kinase (ERK), and certain mitochondrial channels during reoxygenation. Using a dihydrofluorescein fluorescent probe, we detected the production of ROS in mouse diaphragmatic skeletal muscle in real time under confocal microscopy. Muscles treated with Po2 cycling displayed significantly attenuated ROS levels (n = 5; P < 0.001) as well as enhanced force generation compared with controls during reperfusion (n = 7; P < 0.05). We also used inhibitors for signaling molecules or membrane channels such as ROS, Akt, ERK, as well as chemical stimulators to close mitochondrial ATP-sensitive potassium channel (KATP) or open mitochondrial permeability transition pore (mPTP). All these blockers or stimulators abolished improved muscle function with Po2 cycling treatment. This current investigation has discovered a correlation between KATP and mPTP and the Po2 cycling pathway in diaphragmatic skeletal muscle. Thus we have identified a unique signaling pathway that may involve ROS, Akt, ERK, and mitochondrial channels responsible for Po2 cycling protection during reoxygenation conditions in the diaphragm.

Negative regulation of the LKB1/AMPK pathway by ERK in human acute myeloid leukemia cells

Adenosine monophosphate-activated protein kinase (AMPK) is a sensor for cellular energy status. When the cellular energy level is decreased, AMPK is activated and functions to suppress energy-consuming processes, including protein synthesis. Recently, AMPK has received attention as an attractive molecular target for cancer therapy. Several studies have revealed that the activation of AMPK by chemical stimulators, such as metformin, induces apoptosis in a variety of hematologic malignant cells. From another perspective, these results suggest that the function of AMPK is impaired in hematologic tumor cells. However, the precise mechanisms by which this impairment occurs are not well understood. In melanoma cells, oncogenic BRAF constitutively activates the extracellular signal-regulated kinase (ERK) pathway and phosphorylates liver kinase B1, an upstream activator of 5' adenosine monophosphate-activated protein kinase (AMPK), resulting in the inactivation of liver kinase B1 and AMPK. In this study, we analyzed whether ERK is involved in the suppression of AMPK activity using established and primary human leukemia cells. We found an inverse correlation between the intensity of ERK activity and the degree of AMPK activation after stimulation with either glucose deprivation or metformin. We also found that the inhibition of ERK activity by U0126 restored AMPK activation after metformin treatment. Furthermore, a combined treatment with metformin and U0126 enhanced the antileukemic activity of metformin. Importantly, metformin induced ERK activation by suppressing the protein levels of dual specificity phosphatase 6, a negative regulator of ERK. This crosstalk between AMPK and ERK could diminish the antileukemic activity of metformin. Taken together, our present observations suggest a novel therapeutic strategy for improving the efficacy of metformin in treating leukemia.

Control of resin production in Araucaria angustifolia, an ancient South American conifer.

Araucaria angustifolia is an ancient slow-growing conifer that characterises parts of the Southern Atlantic Forest biome, currently listed as a critically endangered species. The species also produces bark resin, although the factors controlling its resinosis are largely unknown. To better understand this defence-related process, we examined the resin exudation response of A.angustifolia upon treatment with well-known chemical stimulators used in fast-growing conifers producing both bark and wood resin, such as Pinus elliottii. The initial hypothesis was that A.angustifolia would display significant differences in the regulation of resinosis. The effect of Ethrel(®) (ET - ethylene precursor), salicylic acid (SA), jasmonic acid (JA), sulphuric acid (SuA) and sodium nitroprusside (SNP - nitric oxide donor) on resin yield and composition in young plants of A.angustifolia was examined. In at least one of the concentrations tested, and frequently in more than one, an aqueous glycerol solution applied on fresh wound sites of the stem with one or more of the adjuvants examined promoted an increase in resin yield, as well as monoterpene concentration (α-pinene, β-pinene, camphene and limonene). Higher yields and longer exudation periods were observed with JA and ET, another feature shared with Pinus resinosis. The results suggest that resinosis control is similar in Araucaria and Pinus. In addition, A.angustifolia resin may be a relevant source of valuable terpene chemicals, whose production may be increased by using stimulating pastes containing the identified adjuvants.

Assessment of decreasing of allelopathic effect of Juglans regia on germination properties of Melilotus officinalis under Influence of chemical stimulators

This test was conducted on laboratory condition to investigate the allelopathic effect of Juglans regia on germination and early seedling growth of Melilotus officinalis. Pretreatment with gibberellic acid and salicylic acid also was used to decrease the adverse effect of allelopathic components. Three levels of gibberellic acid (125, 250 and 500 ppm) and salicylic acid (100, 200 and 300 mg/L) and five extract levels of Juglans regia (0, 25, 50, 75 and 100 %) was used in the test. This experiment was carried out as factorial experiment based on a randomized completely design with four replications. The results of ANOVA and compare mean test showed that Juglans regia extract had inhibitive effect on germination and early seedling growth of Melilotus officinalis. Early seedling growth of Melilotus officinalis increased by pretreatment of seeds in chemical stimulators so that the highest effect was observed in gibberellic acid. Interaction effects of allelopathic and pretreatment with chemical stimulators were significance on germination percentage and speed, root, shoot and plant length and seed vigour index.

Effect of Seed Priming on Improvement of Germination of Vicia Villosa Under Allelopathic Components of Eucalyptus Camaldulensis

AbstractThe objective of this study was to evaluate the effectiveness of seed priming in improving seed germination and seedling vigor ofVicia villosaunder laboratory conditions. Chemical stimulators included: gibberel-lic acid (125,250 and 500 ppm), salicylic acid (100,200 and 300 mg/lit) and extract ofEucalyptus camaldulen-sis(0, 25, 50, 75 and 100 %). This experiment was carried out as factorial experiment based on a randomized completely design, with four replications. The results showed thatEucalyptus camaldulensisextract had in-hibitive effect on germination and early seedling growth ofVicia villosa. Early seedling growth ofVicia villosaincreased by pretreatment of seeds in chemical stimulators so that the highest effect was observed in gibberellic acid (250 ppm). The chemical stimulators don’t have any effect on germination speed. Interaction effects of allelopathic and pretreatment with chemical stimulators were significance on germination percentage, root, shoot and plant length and seed vigor index.

Influence of the physicochemical nature of chemical stimulators and the way they are introduced into a system on the mechanism of the thermal oxidation of GaAs and InP

Studies of the chemically stimulated thermal oxidation of GaAs and InP demonstrate that the physicochemical nature of the chemical stimulator determines the mechanism of the process and the possibility of introducing it into the system in different ways. It has been shown that, when a chemical stimulator is introduced through the gas phase or applied to a semiconductor surface by mild methods, the oxidation process follows an oxygen transfer mechanism. When harsh methods are used to apply chemical stimulators that ensure persistent cyclic behavior of the process, it follows a synchronous catalytic mechanism.

Stages based molecular mechanisms for generating cholangiocytes from liver stem/progenitor cells

Except for the most organized mature hepatocytes, liver stem/progenitor cells (LSPCs) can differentiate into many other types of cells in the liver including cholangiocytes. In addition, LSPCs are demonstrated to be able to give birth to other kinds of extra-hepatic cell types such as insulin-producing cells. Even more, under some bad conditions, these LSPCs could generate liver cancer stem like cells (LCSCs) through malignant transformation. In this review, we mainly concentrate on the molecular mechanisms for controlling cell fates of LSPCs, especially differentiation of cholangiocytes, insulin-producing cells and LCSCs. First of all, to certificate the cell fates of LSPCs, the following three features need to be taken into account to perform accurate phenotyping: (1) morphological properties; (2) specific markers; and (3) functional assessment including in vivo transplantation. Secondly, to promote LSPCs differentiation, systematical attention should be paid to inductive materials (such as growth factors and chemical stimulators), progressive materials including intracellular and extracellular signaling pathways, and implementary materials (such as liver enriched transcriptive factors). Accordingly, some recommendations were proposed to standardize, optimize, and enrich the effective production of cholangiocyte-like cells out of LSPCs. At the end, the potential regulating mechanisms for generation of cholangiocytes by LSPCs were carefully analyzed. The differentiation of LSPCs is a gradually progressing process, which consists of three main steps: initiation, progression and accomplishment. It's the unbalanced distribution of affecting materials in each step decides the cell fates of LSPCs.

Influence of some chemical compounds on germination and early seedling growth of two range species under allelopathic conditions

Seed priming technique has been known to improve germination and seedling emergence under different environment stresses. The objective of this study was to evaluate the effectiveness of seed priming in improving the seed germination and seedling vigor of Agropyron elongatum and Bromus inermis in response to five concentrations of the allelopathic extract of Thymus kotschyanus (0, 5%, 25%, 50% and 75%) under laboratory conditions. Pretreatments included gibberellic acid (250, 500 and 1000 ppm), potassium nitrate (0.1%, 0.2% and 0.3%) and salicylic acid (100, 200 and 300 mg/L). This experiment was carried out as a factorial experiment based on a completely randomized design with four replications. The results showed that seed germination, germination speed and seedling vigor were significantly decreased (P < 0.01) by increasing extract concentrations of Thymus kotschyanus allelopathic compounds in unprimed seed (control) compared with primed seeds. Seed priming enhanced germination percentage, germination speed and initial growth. Overall, the results of this study showed that the response of both species to pretreatment of seeds was positive. Therefore, pretreatments of seeds with the aforementioned chemical stimulators before planting can significantly reduce the negative effect of allelopathic compounds in Thymus kotschyanus during the germination stage and contribute to plant establishment by increasing germination speed and growth of embryos.

Hücre İçi Sinyal Yolakları ve Klinik Yansımaları

Cellular signaling pathways have important roles in cellular growth, differentiation, inflammatory response and apoptosis and in regulation of cellular responses under various chemical stimulators. Different proteins which belong to these pathways may be exposed to loss-of-function or gain-of-function mutations; this may lead to many clinical phenotypes including primarily cancer. In this review information about basic working principles of these pathways and diseases related to them are included.