Synergistic Effect

It is well known in the practice of S otation that mixtures of various collectors often behave with greater effectiveness than would be expected from their individual known characteristics. This phenomenon is a classical example of synergism in S otation, in which the combined effect exceeds the sum of the linearly weighted partial effects. Such phenomena are not only consciously applied by adding mixtures of reagents, especially collectors, but may also occur inadvertently since many indus- trial reagents are synthesized from less than absolute- ly pure chemicals, resulting in the presence of small amounts of different product molecules which are often capable of having a positive synergistic effect on the S otation behaviour. Such synergism can have a signi R cant effect not only on the recovery but also on the selectivity of speci R c min- erals in differential S otation. The manner in which reagents interact in order to achieve a synergis- tic effect is a complex function of their chemical nature as well as their chemisorptive or physisorptive properties. The former will determine whether the chemical composition of the reagent changes when another compound is present through, for example, a dimerization reaction. The latter will determine how competitive or synergistic adsorption will in S u- ence the ultimate S otation behaviour. The analysis of synergism between reagents in S otation is compli- cated by the fact that the roles and interactions of the different classes of reagents are dif R cult to isolate due to the complexity of the S otation process, viz. the frother is added to stabilize the froth zone but can also interact with the collector and affect the performance of the collection zone.

of Ca on DOM sequestration to 2-line ferrihydrite. However, the question remains as to what processes are controlling the increase in DOM sorption in the pres- ence of Ca. Antelo et al. through a combination of batch reaction and modeling studies with ferrihydrite, Ca, and arsenate/phosphate, attributed the synergistic effect of Ca on phosphate sorption to Fe–Ca-phosphate ternary complex formation [33]. Organic carbon sorption enve- lope data paired with corresponding aqueous Ca data (Figs.  2, 3, respectively) were observed to have similar trends that were observed for phosphate in Anetelo et al. Results from both systems show that Ca addition limits the decrease in OC, or phosphate, sorption with increas- ing pH. The congruent results of both systems suggest that our system may also facilitate the occurrence of ter- nary complexes. Also, the formation of Ca-bridging at high pH has been thought to potentially have an effect on OM sorption to iron oxides due to the decrease in positively charged surface sites, and subsequent increase in negatively charged surface sites at pH  ≥  7 [23, 38]. Significant concentrations of a divalent cation such as Ca 2+ in the presence of negatively charged OM and a

The combined effects of chemical and radiation have mostly been studied in unborn babies because of their high sensitivity to these toxicants. The general aspect of the interaction between radiation and chemicals during prenatal development were summarized [1] and later reviewed by Streffer and Muller [2] on the interaction between ionizing radiation and lead. Teratogenic interactions also studied between radiation and cadmium in mice [3]. Combined effect of radiation and cadmium on mouse kidney was studied and found synergistic effect [4]. There are indications that additive or synergistic relationships exist between in vivo application of cadmium and radiation [5].

Some medicinal plants are used traditionally in Saudi Arabia to treat many bacterial infections. Three plants, lemongrass ( Oymbopogon citrates ), lantana ( Lantana ca- mara ), and wild olive leaves ( Olea europaea ) were collected, identified, extracted with either hot water or organic solvents (methanol, diethyl ether, ethyl acetate and n-butanol) to investigate their antibacterial activities against E. coli . The methanol extracts of lemongrass, lantana and olive showed the highest activities against Eshe- richia coil while aqueous extract exhibited the lowest activities. Thus, the antibacteri- al activities of the methanolic extract of the three tested plants were determined using agar well diffusion method against some bacterial pathogens, isolated from urine samples. The highest antibacterial activity was recorded for themethanolic extract of lemongrass against all tested bacteria, E. coli , K. pneumoniae , P. aeuroginosa , P. mi- rabilis , E. faecalis and S. aureus. The tested bacteria differed with regard to their sus- ceptibility to plant extracts. Lemongrass was the most active extract followed by lan- tana and wild olive extracts. Minimal inhibitory concentrations (MICs) of the me- thanolic extract of Lemongrass and some used antibiotics, Erythromycin, Tetracyc- line, Amoxicillin, Ciprofloxacin and Chloramphenicol were determined usingfluo- rescein diacetate method. Synergistic effect of the methanolic extract of lemongrass with the previous antibiotics against the tested clinical bacterial isolates was deter- mined and the Fractional inhibitory concentrations (FIC) of different combination of the extract and the antibiotics were determined. FIC index (FICI) was calculated and it was ranged from 0.08 - 0.98. The interaction between the tested plant extract and the tested antibiotics was either synergistic or additive effects and no antagonistic ef- fect was recorded. In conclusion, methanolic extract of lemongrass singly or in com- bination with some antibiotics can be used to treat pathogenic bacteria that cause urinary tract infections.

The answer to the question “What does synergism actually mean?” is generally vague, as it is obvious in the following concept definitions. “An interaction between two or more agents, entities, factors, or sub- stances that produces an effect greater than the sum of their individual effects. Also called synergetic effect or synergistic effect, it is the opposite of antagonism” (Antony 2003). An example of antagonistic effect is the effect between the opposing actions of insulin and glucagon to the blood sugar level. While insu- lin lowers the blood sugar, glucagon raises it. Thus, regulating the major physiological function of these two chemicals is crucial in order to keep up a healthy level of glucose in blood.

Results: In this study, H. pylori were isolated from 53 (53%) biopsy specimens. Of these, 49 (5.92%) were resistant to metronidazole, 14 (26%) to amoxicillin, 10 (19%) to clarithromycin, 7 (13%) to tetracycline, 13 (5/24%) to furazolidone and 7 (13%) to ciprofloxacin. In survey of synergistic effect, an increase in inhibition zone diameter around of combined disks was seen up to 5mm compared to the most effective antibiotic.

The present study deals with green synthesis of AgNPs using leaves extract of an important agricultural weed, Amaranthus retroflexus. On the basis of the available literature, we hypothesized that agricultural weeds can be utilized for the preparation of nanoparticles which shows the additional advantages of this study to make the use of agricultural waste. On the other hand, several pathogenic bacteria have developed resistance against various antibiotics and the development of resistant pathogens has become a major problem. With the prevalence and increase of microorganism’s resistant to multiple antibiotics, many researchers have tried to develop new, effective antimicrobial reagents, free of resistance and cost-effective. According to such problems and needs in this study antibacterial activity of biosynthesized AgNPs and its synergistic effect with antibiotic was studied against some of the antibiotic resistant human and plant pathogenic bacteria, considering the lower propensity of AgNPs to induce microbial resistance.

Cement systems require special design attention, modified testing procedures and special systems. Accurate data collection is key to a successful job design. Cement tests are done in the cementing laboratory using the pressure and temperature at well total depth. It is also recommended to utilize the maximum temperature in the annular space where the cement slurry is going to be placed during the temperature simulation. Whatever the case might be, it is imperative to understand the combined effect of temperature and pressure on cement slurry during and after placement. This study has been able to demonstrate that thickening time of cement slurry reduces as temperature and pressure increases.

Repaglinide is a hypoglycemic drug and is poorly soluble in water, which affects bioavailability. As per BCS classification, bioavailability depends on both solubility and permeability of drug. In the present work, the possibility of improving solubility of repaglinide by complexation with cyclodextrins and then complex formation of drug with Hydroxypropyl β-cyclodextrin (HP β-CD) in solid form were investigated. The effect of basic pH and co-solvent, ethanol on solubilization of repaglinide by HP β-CD were also studied. The phase solubility studies indicated formation of repaglinide-β-CD and repaglinide-HP β-CD inclusion complexes at 1:1 M ratio in solutions with stability constant of 182.18 M -1 and 374.54 M -1 respectively. The solubility was markedly enhanced in basic pH and by addition of co-solvent ethanol.

Using only pairs of viability values of outbred and inbred progenies computed from Analysis I, the values of A , B, and the B / A ratio were estimated by the method of M[r]

NPs have been previously reported to inhibit gram-positive bacteria such as Staphylococcus spp [11, 12] Streptococcus spp. [13], and Bacillus spp [14, 15], and gram-negative bacteria such as Escherichia spp [16], Pseudomonas spp [17], Salmonella spp [18], Shigella spp [17, 21], Proteus spp. [21, 22], and Vibrio spp. [21, 23]. More promising, NPs have also shown potential to inhibit antibiotic-resistant bacteria such as Methicillin-resistant S. aureus (MRSA) [24, 25] and drug-resistant E. coli [26]. Previous studies have also manifested the diverse mechanisms for the silver Nanoparticles’ bactericidal effect. Besides that AgNPs interact with the surface of the membrane, they can also penetrate into the bacterial cell membrane [27]. Moreover, silver Nanoparticles can attach to the DNA inside the bacterial cells, suppressing its replication or interaction with the bacterial ribosome [28]. It has been observed that silver Nanoparticles have the ability to damage the structure of the bacterial cell membranous enzymes, which cause bacterial death eventually [29]. The goal of this study is to develop new therapeutic antibacterial drug using silver Nanoparticles to combat the growing threat of antibiotic-resistant bacteria.

Abstract: Gambogic acid (GA) has a significant anticancer effect on a wide variety of solid tumors. Recently, many nanoparticles have been introduced as drug-delivery systems to enhance the efficiency of anticancer drug delivery. The aim of this study was to investigate the potential benefit of combination therapy with GA and magnetic nanoparticles of Fe 3 O 4 (MNPs-Fe 3 O 4 ). The proliferation of K562 cells and their cytotoxicity were evaluated by MTT assay. Cell apoptosis was observed and analyzed by microscope and flow cytometry, respectively. Furthermore, real- time polymerase chain reaction and Western blotting analyses were performed to examine gene transcription and protein expression, respectively. The results showed that MNPs-Fe 3 O 4 dramati- cally enhanced GA-induced cytotoxicity and apoptosis in K562 cells. The typical morphological features of apoptosis treated with GA and MNPs-Fe 3 O 4 were observed under an optical micro- scope and a fluorescence microscope, respectively. The transcription of caspase-3 and bax gene in the group treated with GA and MNPs-Fe 3 O 4 was higher than that in the GA-alone group or MNPs-Fe 3 O 4 -alone group, but the transcription of bcl-2, nuclear factor-κB, and survivin degraded as did the expression of corresponding proteins in K562 cells. Our data suggests a potential clinical application of a combination of GA and MNPs-Fe 3 O 4 in leukemia therapy.

4OH ¹ . 6) The results indicate that although acidic pH is more suitable for chemical Se removal by ZVI alone, as was reported by Yoon et al., 5) to optimize the condition for the synergistic effect by T. selenatis and ZVI, the pH should be set at around 7 which is optimal for growth of T. selenatis. 22) Figure 4(c) again indicates that aerobic respiration by T. selenatis quickly consumes dissolved oxygen during the first 20 hours, which is then switched to anaerobic Se(VI) respiration.

Kiirika et al. (2013) reported for the first time the synergistic effect of mixture of chitosansilica induced resistance in tomato against bacterial wilt caused by Ralstonia solanacearum [16]. To the best of our knowledge, no research on the effect of mixture of oligochitosannanosilica for plants has been reported yet. With the aim of contribution to promoting organic farming, in the present study, oligochitosan was prepared by gamma Co-60 irradiation degradation of chitosan in solution and nanosilica was prepared from rice husk. The effect of foliar application of oligochitosan and mixture of oligochitosannanosilica on the enhancement of soybean seed yield was investigated.

The disk diffusion susceptibility test was carried out to analyze the effect of the essential oil on antibiotic activi- ty. The essential oil was studied at a 4% concentration, which corresponds to the MIC determined in previous studies for the microorganisms tested here [2-4,13,24-26]. The disks containing the antibiotics in their respective concentrations were impregnated with 20 μL of 4% es- sential oil (MIC), and then placed on sterile Petri plates containing Mueller-Hinton agar inoculated with 1 mL of bacterial suspensions. After incubating the plates at 37˚C for 48 h, the effect of the essential oil MIC on the activity of antibiotics was observed. Synergistic effect was con- sidered when inhibition zones ≥2 mm diameter were ob- served surrounding disks containing the essential oil (EO) and the antibiotic (AB). Antagonistic effect was consi- dered when an inhibition zone of smaller diameter was observed around the disks with AB and EO, compared to that developed by the AB disks. Indifferent effect was considered when there was a zone of inhibition sur- rounding the disks with AB and EO, with a diameter equal to that resulting from the application of the AB alone [27]. All assays were performed in duplicate and the results were obtained by averaging the results of the parallel tests.

and molecular phenomenon of cancer cells. Two or more agents used in combination chemotherapy should perform synergistic effect, either act on the same target or not. An example for clinically accepted combination chemotherapy is combination of trastuzumab and docetaxel for HER2 positive breast cancer (Bullock and Blackwell, 2008). Trastuzumab triggers HER2 internalization and degradation as well as cause antibody-dependent cellular cytotoxicity. The most recognized mechanism of trastuzumab is to inhibit the MAPK and PI3K/Akt pathways, leading to an increase in cell cycle arrest, and the inhibition of cell growth and proliferation (Vu and Claret, 2012).

The synergistic enhancement factor, R, was determined using Error! Reference source not found. and presented in Table 1. Synergistic enhancement determines whether the binary extraction system creates synergism or antagonism. If R>1 means synergistic extraction occur whereas R<1 means antagonism. The results indicate that synergistic reaction takes place at all three ions with Y been the highest and the synergistic effect is increase with increasing ionic radii of the rare earth.

Nanotechnology has emerged as one the most prominent field of study among researchers nowadays and nanoparticles have the potential to be a viable and good option in combating bacterial resistance that has become a growing concern among health practitioners. Silver nanoparticles in particular have been in the spotlight due to its unique properties and excellent antimicrobial properties. Current study reported the synthesis of silver nanoparticles from the aqueous extract of Hibiscus sabdariffa plant belongs to family malvaceae. Addition of silver nitrate to cell free extract showed quickly change in color that indicates the production of nanoparticles. The UV-Visible spectroscopy analysis showed the absorption peak at 422.15 nm that confirms the presence of silver nanoparticles. TEM analysis revealed spherically shaped nanoparticle, well distributed with size ranges from 19 mm to 50 mm. The synthesized silver nanoparticles showed good antibacterial effect when tested against Salmonella enterica, Escherichia coli, Bacillus cereus and Staphylococcus aureus. These nanoparticles showed good synergistic effect along with levofloxacin and amikacin.

The synergistic effect of the STAT3 inhibitor LY5 and the EGFR inhibitor erlotinib on human CRC cells was inves- tigated in the HCT116 and DLD-1 CRC cell lines treated with STAT3 inhibitor LY5 and erlotinib, separately or in combination, for 48 or 72 h, by evaluating cell viability using the MTT assay. The inhibitory effect of the combi- nation of LY5 with erlotinib on CRC cells was statistically signi fi cant and more pronounced than that of LY5 or erlotinib alone, with almost all of combination index CI <0.5 (Figure 1A and B). Also, as anticipated, in HCT116, DLD-1 and RKO cells, the cell scratch test demonstrated that the combination of LY5 or another STAT3 inhibitor napabucasin and erlotinib synergistically inhibited cell migration more signi fi cantly than that either inhibitor alone (Figure 2A – C). Moreover, napabucasin combined with erlotinib had a more obvious inhibitory effect on migration factor MMP-2 than napabucasin or erlotinib alone in RKO cells (Figure 2D).Together, these results showed that the combination of STAT3 inhibitor and EGFR inhibitor exerted a signi fi cant synergistic cell growth inhibitory on human CRC cells.

NXF1 provides a key molecular link between mRNA and components of the nuclear pore complex. A possible model to explain the synergistic effect of RTE and CTE is that the duplication of these export elements may provide an improved target for NXF1 resulting in more efficient nucleocytoplasmic mRNA transport. Using in vitro gel- shift assays, we found that the binding of NXF1 (aa 61– 372) to radiolabeled CTE is competed similarly by both excess cold CTE as well as RTEm26-CTE RNAs (data not shown). These data indicate that NXF1 binds to CTE as well as to the RTEm26-CTE RNA targets with similar affin- ity. We have previously shown that NXF1 is not a high affinity binder of RTE when compared to the CTE [6], sug- gesting the role of a distinct cellular protein mediating RTE RNA export. It is plausible that this putative factor tethers the RTE-RNAs directly or indirectly to the NXF1 pathway. Therefore, it is likely that the putative RTE-bind- ing protein and NXF1 may act cooperatively. Studies are on-going to delineate the detailed mechanism of function mediating this cooperativity.