Multidrug-resistant bacteria such as extended-spectrum beta-lactamase (ESBL), Enterobacteriaceae, and methicillin-resistant
(MRSA) pose a challenge to the human health care system. MRSA is among the ...major causes of hospital-acquired and community infections.
Therefore, in the present study, we evaluated the antibacterial activity of silver nanoparticles synthesized by
(AgNP
) in combination with simvastatin against reference and multidrug-resistant bacterial strains.
Simvastatin showed a minimal inhibitory concentration (MIC) ranging from 0.062 to 0.25 mg mL
against MRSA. AgNP
with a size of 77.68± 33.95 nm and zeta potential -34.6 ± 12.7 mV showed an MIC of 0.212 mg mL
against
including MRSA strains. The checkerboard assay and time-kill curves exhibited a synergistic effect of the simvastatin-AgNP
combination on antibacterial activity against MRSA strains. The combination of simvastatin and AgNP
demonstrated antibacterial activity against
producing ESBL. Scanning electron microscopy showed the formation of cell surface protrusions after treatment with AgNP
and the formation of a large amorphous mass after treatment with simvastatin, both in MRSA.
Our results indicate that the combination of AgNP
and simvastatin could be a great future alternative in the control of bacterial infections, where, when combined with simvastatin, smaller doses of AgNP
are required, with the same antibacterial activity.
Several studies have tested antimicrobial activity of combinations of honey and various substances. In this study, we tested a combination of two stingless bee honeys against various bacterial ...strains. In particular: the antibacterial activity of honeys produced by Scaptotrigona bipunctata (SB) and Scaptotrigona postica (SP) was evaluated against Gram-positive and Gram-negative bacterial strains by agar well diffusion assays, minimum inhibitory concentration (MIC) assessment, construction of growth and viability curves and scanning electron microscopy (SEM). The interaction of the two honeys was also evaluated by the checkerboard assay. Inhibition zones ranged from 8 to 22 mm. The MIC values of the individual honeys ranged from 0.62 to 10% (v v(-1)) and decreased to 1/4 to 1/32 when the honeys were combined. SEM images showed division inhibition and cell wall disruption for the SB and SP honeys, respectively, and these alterations were observed in same field when the SB and SP honeys were combined. This study demonstrated that the natural honeys possess in vitro antimicrobial activity against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. Combination of the SB and SP honeys could lead to the development of new broad-spectrum antimicrobials that have the potential to prevent the emergence of resistant bacterial strains.
Recent evidence suggests that nitric oxide (NO) may function as a second messenger in the intracellular signal transduction pathways. We explored the possibility that NO was involved in the signal ...for triggering apoptosis in smooth muscle cells (SMCs). Chemical NO donors induced SMCs apoptosis in a concentration- and time-dependent manner. The membrane-permeable cGMP analogue, dibutyryl-cGMP, did not induce SMCs apoptosis, and the highly selective inhibitor of cGMP-dependent protein kinase, KT5823, was unable to inhibit the induction of NO-induced SMCs apoptosis. Inhibitor of ADP-ribosyltransferase slightly attenuated the induction of SMCs apoptosis by S-nitroso-N-acetyl penicillamine (SNAP). The inhibitor of Na+-H+antiporter, amiloride, completely inhibited the induction of SMCs apoptosis by SNAP. These results demonstrate for the first time that NO can induce apoptosis in SMCs, suggesting that NO acts as a mediator in the development of atherosclerosis lesion via alterations in the number of SMCs. In addition, the results suggest that NO exert these effects through a pathway that does not involve guanylate cyclase and cGMP-dependent protein kinase.
The effect of wortmannin, which inhibits phosphatidylinositol 3-kinase (PI 3-kinase), on adipocytic differentiation of 3T3-L1 cells was examined. The extent of differentiation was evaluated by the ...staining of adipocytes with Oil Red O and measurement of glycerol 3-phosphate dehydrogenase (GPDH) activity. Wortmannin, at over 100 nM, significantly inhibited adipogenesis of cells treated with isobutyl-methylxanthine, dexamethasone, and insulin with an IC50 value about 50 nM. These results suggest that PI 3-kinase plays a role in adipocytic differentiation of 3T3-L1 cells.
"Topsoil samples were collected from 36 different paddy fields in West Japan. Each soil sample was incubated with a basal salt-medium containing 0.2% OPPEO. Twelve samples possessed OPPEO-degrading ...activity, from which twelve cultures of OPPEO-degrading bacteria were isolated. The isolated bacteria grew on a medium containing 0.2% OPPEO as the sole carbon source, and OP2EO and OP3EO were accumulated in the medium under aerobic conditions. OP1EO and octylphenol, which have often been identified in surface water together with OP2EO, were not observed in this experiment. The bacterial isolates were gram negative and tentatively identified as Pseudomonas putida (10 isolates) and Burkholderia cepacia (one isolate) by BIO-LOG and 16S rDNA RFLP analyses. "
Topsoil samples were collected from eight golf courses in Yamaguchi Prefecture, Japan, and enrichment cultures were carried out with a basal-salt medium containing 0.2% 4-tert-octylphenol ...polyethoxylate (OPPEO) as sole carbon source. OPPEO-degrading activity was detected in one of the samples, from which a strain of OPPEO-degrading bacterium was isolated. The isolated bacterium grew on a nutritionally enriched medium (NE medium) containing 0.2% OPPEO as sole carbon source, and accumulated 4-tert-octylphenol diethoxylate (OP2EO) (63%), 4-tert-octylphenol triethoxylate (OP3EO) (14%), and 4-tert-octylphenol monoettaoxylate (OP1EO) (2%) after 7d cultivation under aerobic conditions. The addition of clay mineral (vermiculite) to the medium accelerated the degradation of OP2EO (40%) and OP3EO (4%) to OP1EO (23%). This is the first report about bacteria that can degrade OPPEO to OP1EO under aerobic conditions. The strain was identified as Sphingomonas macrogohabidus, based on the homology of a 16S rDNA sequence.
Three silica gel sample systems, modified with 3-aminopropyltriethoxysilane (APTS), were prepared by sequentially sampling the reaction mixture at various time intervals, and the diffuse reflectance ...infrared Fourier transform (DRIFT) spectra of these samples were measured in the regions 2700-3500 and 1300-2000 cm^sup -1^. The IR bands observed at 1597 and 1629-1633 cm^sup -1^ were assigned to the deformation modes of NH^sub 2^ and NH^sub 3^^sup +^ groups, respectively. The intensities of these two bands are dependent on both the APTS concentration used in the preparation and the reaction time. The results are summarized as follows. For the sample systems in which smaller APTS concentration were used, most of the NH^sub 2^ groups of the aminopropyl segments are converted into the NH^sub 3^^sup +^ groups on the surface, showing that the SiO^sup -^ H^sup +^ NH^sub 2-^ type structure is predominantly stabilized on the surface of the silica gel. As the APTS concentration in the reaction mixture increases, the population of NH^sub 2^ groups in the silane layer coated onto the surface increases. Interpretation of the CH stretch region further suggests that cyclic structures may be formed on the surface as a consequence of the formation of NH^sub 3^^sup +^ groups.PUBLICATION ABSTRACT
Silica gel samples, modified with 3-mercaptopropyltriethoxysilane, and their S-S-bridged samples have been prepared. In order to characterize the microstructure of the surface of these silica gel ...samples, Raman scattering and diffuse reflectance Fourier transform IR spectra of these samples have been examined by comparison with Raman spectra of various n-alkyl disulfides and their related silane polymers. The S-S and C-S stretch modes characteristic of the CH^sub 2^SSCH^sub 2^ segment, in addition to the SH and C-S stretch modes of the CH^sub 2^SH segment, have been assigned for these silica gel samples. It has been found that, even on the surface of the silica gel, a specific conformer is stabilized about the CH^sub 2^SSCH^sub 2^ segment.PUBLICATION ABSTRACT
In the present study, we investigated the mechanism of phenylephrine (α1-adrenergic receptor agonist)-induced arachidonic acid release in Japanese white rabbit aortic smooth muscle cells (SMC). When ...introduced into permeabilized smooth muscle cells, guanosine S-γ-thio triphosphate (GTPγS), which activates GTP-binding proteins (G proteins), stimulated arachidonic acid (AA) release. Neomycin, an inhibitor of phospho-inositide (PI) turnover, was almost without effect on GTPγS stimulated AA release. In addition, pertussis toxin (PT) partially inhibited phenylephrine-stimulated AA release, suggesting that IAP (Islet activating protein)-sensitive G proteins mediate this process. Phenylephrine-stimulated AA release was also inhibited by decreased extracellular calcium and aristolochic acid, suggesting a role for a phospholipase A2(PLA2). Next PLA2is reported to be a substrate for mitogen-activated protein (MAP) kinase. We examined the effect of phenylephrine on MAP kinase and c-jun N-terminal kinase (JNK) phosphorylation. Phenylephrine didn't induce phosphorylation of MAP kinase, but did induce phosphorylation of JNK. In addition, cells which were pretreated with PT inhibited the phosphorylation of JNK. These results suggest that IAP-sensitive G protein is involved in the coupling between α1-adrenergic receptor (AR) and PLA2in cultured rabbit aortic SMCs, and that the α1-AR-induced AA release is mediated by JNK.
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