High Degree Of Inhibition Research Articles

Molecular docking and dynamics of Annona muricata L. megastigmanes and metabolites on enzyme markers of breast cancer and their effect on heterodimer formation

Objective: To analyze the molecular docking of secondary metabolites of soursop on the enzyme markers of breast cancer. Design/Methodology/Approach: Crystals of PARP2 and PRMT5 enzymes were obtained from RCSB-PDB. Both crystals were processed using bioinformatic tools (e.g., SWISS-MODEL, UCSF-Chimera, and ScanProsite), prior to molecular docking and dynamics. The Annona muricata L. metabolites were obtained from Pubchem for their use in several in silico analysis. The Autodock algorithm was used to obtain the molecular docking. Once the most stable conformations were obtained for the ligands of each enzyme, their complexes were subjected to 10 ns of molecular dynamics using GROMACS. Meanwhile, the HPF1-PARP2 and the MEP50-PRMT5 heterodimeric interactions were carried out using the HDOCK server. Finally, the possible biotransformation reactions were studied using QSAR models. Results: The kaempferol-3-O-rutinoside metabolite showed potential biopharmaceutical use as an inhibitor of the PARP2 enzyme. The coreximin ligand showed potential biopharmaceutical use as an inhibitor of the PRMT5 enzyme. The inhibitor impacted the PRMT5-MEP50 interaction. The QSAR models indicated that methylation, O-glucuronidation, and O-dealkylation were the most likely biotransformation reactions among the metabolites with the highest degree of inhibition. Study Limitation/Implications: in silico analysis on inhibition of key proteins. Findings/Conclusions: The kaempferol-3-O-rutinoside chemical compound showed potential as a PARP2 inhibitor. The coreximin chemical compound showed potential as a PRMT5 inhibitor. The protein-protein interaction between PRMT5 and MEP50 was impacted by the inhibitor; however, this was not the case with the PARP2 enzyme.

The Inhibitory Activity of Lactobacillus plantarum Supernatant against Enterobacteria, Campylobacter, and Tumor Cells.

Cell-free supernatant of Lactobacillus plantarum exhibit a strong antimicrobial effect against a number of pathogenic enterobacteria (E. coli, Shigella flexneri, Salmonella typhimurium, Proteus mirabilis, and Campylobacter jejuni). The degree of growth inhibition in broth culture reached a high level for all tested bacteria. The highest rates were noted for P. mirabilis (by 13 times) and the lowest for S. flexneri (by 5 times) and C. jejuni (by 4.5 times). Significant antiproliferative effect of the supernatant on cells of tumor-derived epithelial cell lines was shown. The highest degree of inhibition (by 22 times) was observed for HT-29 cells (colon carcinoma). Thus, inclusion of probiotics in traditional treatment schemes can increase the effectiveness of antibacterial and antitumor drug therapy.

Interactive effects of drought and cadmium stress on adzuki bean seedling growth, DNA damage repair, and Cd accumulation

Cadmium (Cd) is one of the most toxic heavy metal pollutants that seriously affects crop survival and human health. Drought is a common abiotic stress that affects crop production and yield. However, appropriate drought treatment can be used as a tillage measure to reduce the growth inhibition and toxic accumulation of Cd in plants. In this study, Adzuki bean (Vigna angularis L., cultivar Pearl red) seedlings were hydroponically grown to investigate the effects of Cd (2.5 mg·L-1 CdCl2), drought (D, 5 % (W/V) PEG6000), and combined stress of Cd and drought (Cd+D) on the plant growth. Compared with the control group, Cd, D, and Cd+D stress significantly inhibited the growth of adzuki bean seedling plants, among which Cd+D stress had the highest degree of inhibition. Compared with Cd stress, Cd+D treatment significantly up-regulated the expression levels of Cd ion transport-related genes in adzuki bean seedling roots, resulting in a decrease in Cd accumulation. In addition, Cd+D treatment significantly increased the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), but significantly decreased the activities of peroxidase (POD) and catalase (CAT) enzymes, which led to a decrease in superoxide anion (O2-) content and an increase in hydrogen peroxide (H2O2) content in seedling roots. Compared with Cd stress, Cd+D treatment slowed down the G1/S phase of root cells; however, promoted the G2/M phase. Although Cd+D treatment up-regulated the expression levels of DNA damage repair genes in the roots of adzuki bean seedlings under Cd stress, but not significantly reduce the degree of DNA damage, which may due to the existence of a DNA damage tolerance mechanism. This may also be the main reason for the inhibition of the adzuki bean growth.

Evaluation of Phytochemical Profile and In Vitro Antioxidant, Anti-bacterial and Anti-inflammatory activity of Piper schmidtii Hook. fil. A Wild Edible Fruit

Aim: The present study aims at screening the phytochemical components and evaluates the antioxidant, anti-bacterial, and anti-inflammatory activity of fruit of Piper schmidtii, an endemic plant species from The Nilgiris, Tamil Nadu. Materials and Method: The different polar solvents such as petroleum ether, chloroform, ethyl acetate, methanol, and water were used and extraction was carried out using the soxhlet apparatus. The extracts were screened for qualitative and quantitative phytochemical analysis. The extracts of P. schmidtii were also subjected to in vitro-antioxidant activity by DPPH assay, Phosphomolybdenum assay, Ferric reducing antioxidant power (FRAP), superoxide radical scavenging activity, and reducing power assay. Results: Among all the extracts, methanol extract exhibited the maximum amount of phenolics (731.91 mg GAE/g extract), tannin (726.6 milligrams of Gallic acid equivalent/g extract), and ethyl acetate extract depicted the maximum quantity of flavonoids (698.17 mg QE/g extract). Methanol extract of P. schmidtii revealed the higher antioxidant activity in all the assays with IC50 values of 15.19 μg/ml (DPPH), 135.67 mg AAE/g (Phosphomolybdenum assay), 380.98 mM Fe/mg (FRAP), 60.94% (Superoxide) and higher reducing power was depicted in the ethyl acetate extract, respectively. Further anti-bacterial activity revealed that the methanol extract shows highest inhibitory activity against the tested bacterial pathogens. The methanol extract showed high degree of inhibition (71.24%) in anti-inflammatory assay. Conclusion: Thus, the result support that P. schmidtii is a potential source of natural antioxidant that can inhibit bacterial growth and subside inflammation.

Anti-Inflammatory Effect of Three Novel Hydroxy Flavones

Aim: The aim of the present study was to evaluate the anti-inflammatory effect of three 7-hydroxy flavone derivatives; 7-HF, 7,3’,4’-THF, and 7,8,3’-THF,
 Materials and Methods: The acute anti-inflammatory effect of 7-hydroxy flavones was the effect of 7-hydroxy flavones on certain mediators of pain and inflammation like cyclooxygenases (COX-1 and COX-2), and pro-inflammatory cytokines (IL-1b and TNF- were investigated by using in vitro tests.
 Results: The investigated 7hydroxy flavones produced a significant, the test compounds inhibited both the isoforms of cyclooxygenase, a higher degree of inhibition on COX-2 was evident. Concentration-dependent inhibition of other inflammatory cytokines like tumour necrosis factor-a and interleukin-1b was identified in the present study
 Conclusion: conclusion of the present study reveal the pain and anti-inflammatory action of the investigated 7hydroxy flavones. The inhibitory effects of 7hydroxy flavone on various pro-inflammatory cytokines provide evidence for the mechanism of action of these compounds against pain and inflammation.

3,4-dihydroxytoluene, a metabolite of rutin, suppresses the progression of nonalcoholic fatty liver disease in mice by inhibiting p300 histone acetyltransferase activity.

3,3',4',5,7-Pentahydroxyflavone-3-rhamnoglucoside (rutin) is a flavonoid with a wide range of pharmacological activities. Dietary rutin is hardly absorbed because the microflora in the large intestine metabolize rutin into a variety of compounds including quercetin and phenol derivatives such as 3,4-dihydroxyphenolacetic acid (DHPAA), 3,4-dihydroxytoluene (DHT), 3,4-hydroxyphenylacetic acid (HPAA) and homovanillic acid (HVA). We examined the potential of rutin and its metabolites as novel histone acetyltransferase (HAT) inhibitors. DHPAA, HPAA and DHT at the concentration of 25 μM significantly inhibited in vitro HAT activity with DHT having the strongest inhibitory activity. Furthermore, DHT was shown to be a highly efficient inhibitor of p300 HAT activity, which corresponded with its high degree of inhibition on intracellular lipid accumulation in HepG2 cells. Docking simulation revealed that DHT was bound to the p300 catalytic pocket, bromodomain. Drug affinity responsive target stability (DARTS) analysis further supported the possibility of direct binding between DHT and p300. In HepG2 cells, DHT concentration-dependently abrogated p300-histone binding and induced hypoacetylation of histone subunits H3K9, H3K36, H4K8 and H4K16, eventually leading to the downregulation of lipogenesis-related genes and attenuating lipid accumulation. In ob/ob mice, administration of DHT (10, 20 mg/kg, iv, every other day for 6 weeks) dose-dependently improved the NAFLD pathogenic features including body weight, liver mass, fat mass, lipid accumulation in the liver, and biochemical blood parameters, accompanied by the decreased mRNA expression of lipogenic genes in the liver. Our results demonstrate that DHT, a novel p300 histone acetyltransferase inhibitor, may be a potential preventive or therapeutic agent for NAFLD.

Two Novel Peptide Toxins from the Spider Cyriopagopus longipes Inhibit Tetrodotoxin-Sensitive Sodium Channels.

Sodium channels play a critical role in the generation and propagation of action potentials in excitable tissues, such as nerves, cardiac muscle, and skeletal muscle, and are the primary targets of toxins found in animal venoms. Here, two novel peptide toxins (Cl6a and Cl6b) were isolated from the venom of the spider Cyriopagopus longipes and characterized. Cl6a and Cl6b were shown to be inhibitors of tetrodotoxin-sensitive (TTX-S), but not TTX-resistant, sodium channels. Among the TTX-S channels investigated, Cl6a and Cl6b showed the highest degree of inhibition against NaV1.7 (half-maximal inhibitory concentration (IC50) of 11.0 ± 2.5 nM and 18.8 ± 2.4 nM, respectively) in an irreversible manner that does not alter channel activation, inactivation, or repriming kinetics. Moreover, analysis of NaV1.7/NaV1.8 chimeric channels revealed that Cl6b is a site 4 neurotoxin. Site-directed mutagenesis analysis indicated that D816, V817, and E818 observably affected the efficacy of the Cl6b-NaV1.7 interaction, suggesting that these residues might directly affect the interaction of NaV1.7 with Cl6b. Taken together, these two novel peptide toxins act as potent and sustained NaV1.7 blockers and may have potential in the pharmacological study of sodium channels.

The effects of combination treatments on drug resistance in chronic myeloid leukaemia: an evaluation of the tyrosine kinase inhibitors axitinib and asciminib

BackgroundChronic myeloid leukaemia is in principle a treatable malignancy but drug resistance is lowering survival. Recent drug discoveries have opened up new options for drug combinations, which is a concept used in other areas for preventing drug resistance. Two of these are (I) Axitinib, which inhibits the T315I mutation of BCR-ABL1, a main source of drug resistance, and (II) Asciminib, which has been developed as an allosteric BCR-ABL1 inhibitor, targeting an entirely different binding site, and as such does not compete for binding with other drugs. These drugs offer new treatment options.MethodsWe measured the proliferation of KCL-22 cells exposed to imatinib–dasatinib, imatinib–asciminib and dasatinib–asciminib combinations and calculated combination index graphs for each case. Moreover, using the median–effect equation we calculated how much axitinib can reduce the growth advantage of T315I mutant clones in combination with available drugs. In addition, we calculated how much the total drug burden could be reduced by combinations using asciminib and other drugs, and evaluated which mutations such combinations might be sensitive to.ResultsAsciminib had synergistic interactions with imatinib or dasatinib in KCL-22 cells at high degrees of inhibition. Interestingly, some antagonism between asciminib and the other drugs was present at lower degrees on inhibition. Simulations revealed that asciminib may allow for dose reductions, and its complementary resistance profile could reduce the risk of mutation based resistance. Axitinib, however, had only a minor effect on T315I growth advantage.ConclusionsGiven how asciminib combinations were synergistic in vitro, our modelling suggests that drug combinations involving asciminib should allow for lower total drug doses, and may result in a reduced spectrum of observed resistance mutations. On the other hand, a combination involving axitinib was not shown to be useful in countering drug resistance.

Bio-active sesquiterpenoids and norsesquiternoids from the Red Sea octocoral Rhytisma fulvum fulvum

Three previously undescribed nardosinane-type sesquiterpenes (1–3), together with six known compounds (4–9) were isolated from the alcyonacean soft coral Rhytisma fulvum fulvum. 2 and 3 are 13-nornardosinane, and 6,7-seco-13-nornardosinane derivatives, respectively. 2 could be an artifact due to C-6 epimerization of the known one 4. Chemical structures were elucidated based on 1 D, 2 D NMR and MS spectral data. Compounds 1-8 showed cytotoxic activity against NCI-H1299, HepG2 and MCF-7 with IC50 values between 0.0352–0.0974, 0.0717–0.3745 and 0.0341–0.1325 mM, respectively. The antibacterial activity of all isolated compounds have examined against a number of Gram-positive (Bacillus cereus, Staphylococcus aureas) and Gram-negative (Escherichia coli, Klebsiella pneumoniae and Pseudomonas sp.) bacteria. Compounds 6 and 7 showed a high degree of inhibition against B. cereus, S. aureus and Pseudomonas sp. Interestingly, neolemnane (6) showed strong inhibition against two fungi, Aspergillus niger and Fusarium oxysporum; while 8 showed positive inhibition against Fusarium oxysporum at 150 µg/mL.

Physicochemical properties and structure of hydrothermally modified starches

The paper presents a study on physicochemical and structure changes of waxy corn and tapioca starches after hydrothermal modification. It was found that with an increase of the degree of inhibition (low < medium < high) the viscosity of gels decreased. The process of inhibition slows down the retrogradation of starch gels, as opposed to native starches. Inhibited starches are characterised by a nearly 15% increase of the water solubility index. With increase in the degree of inhibition, tapioca starches are characterised by increasing values of surface area (SBET H2O), while for waxy corn starches it decreases. It was demonstrated that in the case of tapioca starches the differences in electron density distribution and SAXS scattering decrease with increase in the degree of inhibition (low < medium < high), and increase for the waxy corn starches. In the case of waxy corn starches, the capacity for iodine complexation decreased with low < medium < high degree of inhibition.

Phytotoxic analysis of coastal medicinal plants and quantification of phenolic compounds using HPLC

Medicinal plants are rich sources of bioactive phytochemicals. Production of such chemicals usually increased under unfavorable conditions. This study investigated the phytotoxic potential of 105 medicinal plants distributed in arid/semiarid areas along Arabian Sea coast of Pakistan. Total polyphenols, flavonoids, tannins and composition of individual phenolic compounds were also determined in species which showed high phytotoxic potential. Sandwich method was used to determine the phytotoxicity of medicinal plants on the growth of lettuce seedlings. Radicle growth was inhibited more than the hypocotyl growth. In general, halophytes showed higher phytotoxic potential than non-halophytes. Capparis cartilaginea, Indigofera hochstetteri, Parkinsonia aculeata and Prosopis glandulosa showed highest degree of inhibition. Higher amount of total phenols (16.35–25.33 mg GAE g−1), flavonoids (3.32-6.41 mg QE g−1) and tannins (1.54–2.54 mg TAE g−1) were found in these species. Pyrocatechol, quercetin, gallic, hydroxybenzoic and ferulic acids were detected as major phytotoxins, of which, gallic acid, pyrocatechol and quercetin were most abundant. These phytochemicals could be used for the production of natural, safe, healthy and eco-friendly agro-chemicals. Furthermore, these plants can be grown without encroaching agricultural lands, and can convert vast areas of arid/saline lands into economically viable resources, which also helps to halt climate change and desertification.

Caracterización de un aislado bacteriano causante de manchado rojizo en Sechium edule (Jacq.) Sw.

Existen escasos reportes de enfermedades bacterianas en el cultivo de chayote Sechium edule (Jacq.) Sw , casi todas se atribuyen a otros patógenos, principalmente hongos. El objetivo del proyecto fue Caracterizar e identificar bioquímicamente el aislado bacteriano pigmentado obtenido en Sechium edule (Jacq.) Sw (chayote). Se realizó una colecta de frutos de chayote en mercados de la región seleccionandolos de acuerdo a la sintomatología que consiste en la observación de manchas rojizas a nivel superficial del fruto. Se realizaron cortes que se desinfestaron con hipoclorito de sodio al 3% para eliminar organismos asociados a la infección ubicados superficialmente, se lavaron 5 veces con agua destilada estéril a fin de eliminar el hipoclorito. Las muestras desinfestadas se maceraron en un mortero estéril con un poco de agua destilada, posteriormente se sembraron por la técnica de extensión de placa con varilla acodada diluciones de 10-1 a la 10-7 en cajas con agar nutritivo y papa dextrosa agar. Posteriormente se incubaron a 28° C durante 24 horas. La purificación se llevó a cabo mediante resiembras sucesivas del primo aislamiento. El perfil exoenzimático realizado pone de manifiesto que este microorganismo posee 8 enzimas: Amilasa, esterasas, colagenasas, fosfolipasa, lipasa, caseínasa, DNAsa y quitinasa. De la prueba de sensibilidad bacteriana realizada con antibiograma se observó que la bacteria presentó alto grado de inhibición a los antibióticos: levofloxacina (LEV), netilmicina (NET), gentamicina (GE), trimetropim o sulfametoxazol (SXT), amikacina (Ak), y ceftriaxona (CRO). Con alto grado de resistencia a los antibióticos: cefeprime (FEP), cefotaxima (CTX), y amplicilina (AM). Las pruebas de identificación morfológica, microscópica y bioquímica, dieron como resultado, que el microorganismo problema corresponde a Serratia marcescens.

Effects of Three Months of Aerobic Endurance Training on Motor Cortical Excitability in Schizophrenia Patients and Healthy Subjects

Background: Aerobic endurance training has been discussed to induce brain plasticity and improve cognitive functions in healthy subjects and patients with neuropsychiatric disorders. For schizophrenia, a motor cortical inhibitory deficit has been established as one aspect of impaired plasticity, especially involving impairments in GABAergic interneuron networks, but the possibility to restore these deficits via exercise-induced plasticity has not been evaluated yet. Methods: 17 schizophrenia patients and 16 matched healthy controls underwent 3 months of aerobic endurance training (30 min, 3 times a week) on bicycle ergometers. After 6 weeks, computer-assisted cognitive remediation training (30 min, 2 times a week) was added. Transcranial magnetic stimulation of the left and right hemispheres was performed at baseline and at the end of the intervention. We evaluated the intensity to induce a motor-evoked potential of 1 mV (S1mV), the resting motor threshold (RMT), the cortical silent period (CSP) at an intensity of 120 and 150% of the individual RMT, short-latency interval intracortical inhibition (3 ms), and intracortical facilitation (7 and 15 ms). Depending on the variable and hemisphere, follow-up data was available for 7–15 schizophrenia patients and for 10–12 healthy controls. Results: Repeated measures ANOVA revealed no significant time × group interactions for any of the analyzed variables. A significant increase in S1mV and CSP duration at 150% RMT of the left hemisphere could be observed in both groups over time. Conclusion: Regular ergometer training over 3 months increases motor cortical inhibition as displayed by an increase in CSP. The increase in S1mV may also indicate a higher degree of inhibition after the intervention. We could not establish a difference between schizophrenia patients and healthy controls. Due to the limited sample size, our results have to be considered as preliminary and need to be replicated in future trials.

A single- and multiple-dose study to investigate the pharmacokinetics and pharmacodynamics of opicapone, a novel COMT inhibitor, in rat

Opicapone is a novel catechol-O-methyltransferase (COMT) inhibitor that emerged to fulfil the need of a safer and more efficacious COMT inhibitor. The present study was carried out in order to assess and compare the pharmacokinetics and pharmacodynamics (COMT inhibition) of opicapone after single and multiple oral administrations (30 mg/kg) to Wistar rats. For this purpose, at predefined time points up to 72 h post-dosing, blood, liver and kidneys were collected and, then, the concentrations of opicapone and its active metabolite (BIA 9–1079) were determined in plasma and in liver and kidney tissues, as well as the erythrocyte, liver and kidney COMT activity. No systemic, renal or hepatic accumulation of opicapone was observed following repeated administration. Furthermore, the tissue-systemic exposure relationships to opicapone suggested a low drug exposure in the liver and kidneys. After single-dosing, COMT inhibition profiles were reasonably comparable in all the studied matrices; although similar results were found after multiple-dosing, a higher degree of inhibition was observed, indicating a continuous peripheral COMT inhibition when opicapone is administered once-daily. Despite having a short elimination half-life (≤2.94 h), opicapone showed a strong and long-lasting COMT inhibition in both studies, since more than 50% of the COMT activity was still inhibited at 24 h post-dosing.

Substantiation of feasibility of using black chokeberry in the technology of products from shortcake dough

The feasibility of using black chokeberry fruit in processing the products from shortcake dough was theoretically substantiated and experimentally proved. The influence of black chokeberry additive on the basic formulation component of shortcake dough – wheat flour – was investigated. It was found that the black chokeberry additive not only contributes to enhancing the nutritive value of shortcake dough, but also makes it possible to improve the quality of shortcake dough. The influence of physiologically active compounds of BCA on the quality of wheat flour gluten was explored. BCA in the form of powder and its water extract weakens flour gluten, which is a positive factor for the formation of shortcake dough. The gluten capability to stretch increases by 9…23 %, and dough becomes more plastic and does not require any addition of starch, which is often added to formulations with the aim of enhancing plasticity of the formulation mixture. Polyphenol substances of BCA were found to prevent gluten proteins of wheat flour from swelling due to a decrease in its water-retaining capacity, which provides the possibility of its storing for a long time before baking. We established a higher degree of inhibition of amylases in wheat flour by the extract of black chokeberry fruit or its juice compared to the powder from dry fruit. Water-soluble phenolic compounds of black chokeberry in reaction mixture interact with metal cations, existing there, and bind them in strong complexes. The obtained experimental data allow us not only to control hydrolytic processes in the dough semi-finished product, but also to extend the possibility of using wheat flour of lower grades after neutralizing the harmful action of enzymes in it.

NADPH oxidase 4 regulates vascular inflammation in aging and atherosclerosis

We recently reported that increased NADPH oxidase 4 (NOX4) expression and activity during aging results in enhanced cellular and mitochondrial oxidative stress, vascular inflammation, dysfunction, and atherosclerosis. The goal of the present study was to elucidate the molecular mechanism(s) for these effects and determine the importance of NOX4 modulation of proinflammatory gene expression in mouse vascular smooth muscle cells (VSMCs). A novel peptide-mediated siRNA transfection approach was used to inhibit Nox4 expression with minimal cellular toxicity. Using melittin-derived peptide p5RHH, we achieved significantly higher transfection efficiency (92% vs. 85% with Lipofectamine) and decreased toxicity (p<0.001 vs. Lipofectamine in MTT and p<0.0001 vs. Lipofectamine in LDH assays) in VSMCs. TGFβ1 significantly upregulates Nox4 mRNA (p<0.01) and protein (p<0.01) expression in VSMCs. p5RHH-mediated Nox4 siRNA transfection greatly attenuated TGFβ1-induced upregulation of Nox4 mRNA (p<0.01) and protein (p<0.0001) levels and decreased hydrogen peroxide production (p<0.0001). Expression of pro-inflammatory genes Ccl2, Ccl5, Il6, and Vcam1 was significantly upregulated in VSMCs in several settings cells isolated from aged vs. young wild-type mice, in atherosclerotic arteries of Apoe−/− mice, and atherosclerotic human carotid arteries and correlated with NOX4 expression. p5RHH-mediated Nox4 siRNA transfection significantly attenuated the expression of these pro-inflammatory genes in TGFβ1-treated mouse VSMCs, with the highest degree of inhibition in the expression of Il6. p5RHH peptide-mediated knockdown of TGFβ-activated kinase 1 (TAK1, also known as Map3k7), Jun, and Rela, but not Nfkb2, downregulated TGFβ1-induced Nox4 expression in VSMCs. Together, these data demonstrate that increased expression and activation of NOX4, which might result from increased TGFβ1 levels seen during aging, induces a proinflammatory phenotype in VSMCs, enhancing atherosclerosis.

Aging in Ghana

Interferon (IFN)-gamma production, stimulated by the addition of exogenous interleukin (IL) 2, T cell mitogens, or tuberculin purified protein derivative (PPD) was studied in cultures of separated human mononuclear cells or unseparated peripheral blood leukocytes (PBL). IFN-gamma was induced by the addition of IL 2 to cultures of otherwise unstimulated cells. The minimal concentration of exogenous IL 2 required to cause a reproducible stimulation of IFN-gamma was about 10 U/ml, i.e., approximately 50 times the minimal concentration required to stimulate proliferation in an IL 2-dependent murine cytotoxic T cell line. Approximately 500 to 1000 IL 2 U/ml were required to produce maximal stimulation of IFN-gamma production in otherwise unstimulated cultures. Monoclonal antibody anti-Tac, specific for an epitope associated with the IL 2 receptor (IL 2 R), inhibited IFN-gamma induction by exogenous IL 2 less strongly than induction by phytohemagglutinin (PHA) or concanavalin A (Con A). The highest degree of inhibition was exerted by anti-Tac on IFN-gamma production stimulated with PPD. Stimulation of IFN-gamma induction by exogenous IL 2 and the inhibitory action of anti-Tac on IFN-gamma production were also seen in cultures of irradiated (2000 R) cells. Treatment of cells with subinducing doses of Con A or phorbol myristate acetate increased IFN-gamma induction by exogenous IL 2. Taken together, the data suggest that endogenously generated IL 2 is a major mediator of IFN-gamma induction in PBL cultures stimulated with antigens or T cell mitogens.

Anti-inflammatory effect of certain dimethoxy flavones.

The aim of the present study was to evaluate the anti-inflammatory effect of four dimethoxy flavone derivatives; 7,2'-dimethoxy flavone, 7,3'-dimethoxy flavone, 7,4'-dimethoxy flavone and 7,8,-dimethoxy flavone and to investigate the possible cellular mechanisms involved. The acute anti-inflammatory effect of dimethoxy flavones was investigated by carrageenan induced hind paw oedema in rats. Further, the effect of dimethoxy flavones on certain mediators of pain and inflammation like cyclooxygenases (COX-1 and COX-2), pro-inflammatory cytokines (IL-1β and TNF-α) and free radical scavenging activity (NO and LPO) were investigated by using in vitro tests. The investigated dimethoxy flavones produced a significant, dose and time dependent reduction of carrageenan induced paw oedema in rats with a maximum inhibition of 52.4% observed for 7,4'-dimethoxy flavone. Although, the test compounds inhibited both the isoforms of cyclooxygenase, a higher degree of inhibition on COX-2 was evident. A concentration dependent inhibition of other inflammatory cytokines like tumor necrosis factor-α and interleukin-1β was identified in the present study. 7,4'-dimethoxy flavone was found to be maximally effective in inhibiting nitrite ion free radical generation and 7,8-dimethoxy flavone was more active in inhibiting lipid peroxidation than the other compounds. The results of the present study reveal the anti-inflammatory action of the investigated dimethoxy flavones. Inhibition of cyclooxygenases, cytokines and reactive oxygen species, observed in subsequent experiments may be suggested as possible mechanisms involved in the action of these compounds.

Reduced parasite motility and micronemal protein secretion by a p38 MAPK inhibitor leads to a severe impairment of cell invasion by the apicomplexan parasite Eimeria tenella.

E. tenella infection is associated with a severe intestinal disease leading to high economic losses in poultry industry. Mitogen activated protein kinases (MAPKs) are implicated in early response to infection and are divided in three pathways: p38, extracellular signal-regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK). Our objective was to determine the importance of these kinases on cell invasion by E. tenella. We evaluated the effect of specific inhibitors (ERK: PD98059, JNKII: SP600125, p38 MAPK: SB203580) on the invasion of epithelial cells. Incubation of SP600125 and SB203580 with epithelial cells and parasites significantly inhibited cell invasion with the highest degree of inhibition (90%) for SB203580. Silencing of the host p38α MAPK expression by siRNA led to only 20% decrease in cell invasion. In addition, when mammalian epithelial cells were pre-treated with SB203580, and washed prior infection, a 30% decrease in cell invasion was observed. This decrease was overcome when a p38 MAPK activator, anisomycin was added during infection. This suggests an active but limited role of the host p38 MAPK in this process. We next determined whether SB203580 has a direct effect on the parasite. Indeed, parasite motility and secretion of micronemal proteins (EtMIC1, 2, 3 and 5) that are involved in cell invasion were both decreased in the presence of the inhibitor. After chasing the inhibitor, parasite motility and secretion of micronemal proteins were restored and subsequently cell invasion. SB203580 inhibits cell invasion by acting partly on the host cell and mainly on the parasite.

Inhibitive effect of potassium methylsiliconate on hydration swelling of montmorillonite

Herein we report on a study on the inhibition effect of potassium methylsiliconate on hydration swelling of montmorillonite. The results of linear swelling tests showed that potassium methylsiliconate exhibits a high performance as an effective shale inhibitor in drilling fluids. The inhibition mechanism was investigated by means of a variety of methods including Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and zeta potential measurements. The high degree of inhibition is a result of the synergy of action of potassium cations and methylsiliconate anions. Methylsiliconate anions form a hydrophobic shell around each montmorillonite particle through the adsorption on the edge sites, thus inhibiting the penetration of water into the interlayer. The potassium ions promote the formation of a less hydratable structure of montmorillonite through cation-exchange interaction.