Evaluation of antimicrobial activity of thiolated methylated N-(4-N,N-dimethylaminobenzyl) chitosan as a new derivative of chitosan.

Despite chitosan, a natural cationic polysaccharide derived from chitin, being applied as an antimicrobial agent, many studies are being performed for enhancing its capability to fight against pathogens. The aim of this study was to investigate the antibacterial effect of thiolated methylated N-(4-N,N-dimethylaminobenzyl) chitosan (TTMAC) polymer and its nanoparticles as a novel derivation of chitosan. The polymer derivative was synthetized and characterized via 1 H NMR, Fourier transform infrared and the Elman test. The nanoparticles with different N/P ratios were prepared by the ionic gelation method and were characterized by dynamic light scattering and transmission electron microscopy. The cellular toxicity of polymer and nanoparticles at different concentrations were evaluated on human MCF-7 cell line. Antimicrobial assay was performed on Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Candida albicans (ATCC 10231) as Gram-negative, Gram-positive and yeast pathogens, respectively. The obtained results have shown the TTMAC polymer has a higher inhibition activity against microbial pathogens and also lower cellular toxicity in comparison with chitosan polymer. Furthermore, chitosan nanoparticles in comparison with TTMAC nanoparticles have lower size and highest zeta potential in different ratio and chitosan nanoparticles have more inhibitory effects against microbial pathogens. In conclusion, TTMAC derivative in polymeric form can be a promising tool against microbial pathogens.

Lower gastrointestinal bleeding in pregnancy: Differential diagnosis, assessment and management.

Rectal bleeding is a common symptom experienced by pregnant women. Although the majority of cases are attributable to benign conditions such as haemorrhoids and anal fissures, other more serious diagnoses such as inflammatory bowel disease and malignancy should not be overlooked. Most investigations are safe during pregnancy and these should not be withheld as significant implications on both fetal and maternal morbidity may result. In these cases, a multidisciplinary team approach is essential. This review explores the differential diagnosis, investigation and management of rectal bleeding during pregnancy.

Respiratory-gated KES imaging of a rat model of acute lung injury at the Canadian Light Source.

In this study, contrast-enhanced X-ray tomographic imaging for monitoring and quantifying respiratory disease in preclinical rodent models is proposed. A K-edge imaging method has been developed at the Canadian Light Source to very accurately obtain measurements of the concentration of iodinated contrast agent in the pulmonary vasculature and inhaled xenon in the airspaces of rats. To compare the iodine and xenon concentration maps, a scout projection image was acquired to define the region of interest within the thorax for imaging and to ensure the same locations were imaged in each K-edge subtraction (KES) acquisition. A method for triggering image acquisition based on the real-time measurements of respiration was also developed to obtain images during end expiration when the lungs are stationary, in contrast to other previously published studies that alter the respiration to accommodate the image acquisition. In this study, images were obtained in mechanically ventilated animals using physiological parameters at the iodine K-edge in vivo and at the xenon K-edge post mortem (but still under mechanical ventilation). The imaging techniques were performed in healthy Brown Norway rats and in age-matched littermates that had an induced lung injury to demonstrate feasibility of the imaging procedures and the ability to correlate the lung injury and the quantitative measurements of contrast agent concentrations between the two KES images. The respiratory-gated KES imaging protocol can be easily adapted to image during any respiratory phase and is feasible for imaging disease models with compromised lung function.

Multiple energy synchrotron biomedical imaging system.

A multiple energy imaging system that can extract multiple endogenous or induced contrast materials as well as water and bone images would be ideal for imaging of biological subjects. The continuous spectrum available from synchrotron light facilities provides a nearly perfect source for multiple energy x-ray imaging. A novel multiple energy x-ray imaging system, which prepares a horizontally focused polychromatic x-ray beam, has been developed at the BioMedical Imaging and Therapy bend magnet beamline at the Canadian Light Source. The imaging system is made up of a cylindrically bent Laue single silicon (5,1,1) crystal monochromator, scanning and positioning stages for the subjects, flat panel (area) detector, and a data acquisition and control system. Depending on the crystal's bent radius, reflection type, and the horizontal beam width of the filtered synchrotron radiation (20-50 keV) used, the size and spectral energy range of the focused beam prepared varied. For example, with a bent radius of 95 cm, a (1,1,1) type reflection and a 50 mm wide beam, a 0.5 mm wide focused beam of spectral energy range 27 keV-43 keV was obtained. This spectral energy range covers the K-edges of iodine (33.17 keV), xenon (34.56 keV), cesium (35.99 keV), and barium (37.44 keV); some of these elements are used as biomedical and clinical contrast agents. Using the developed imaging system, a test subject composed of iodine, xenon, cesium, and barium along with water and bone were imaged and their projected concentrations successfully extracted. The estimated dose rate to test subjects imaged at a ring current of 200 mA is 8.7 mGy s-1, corresponding to a cumulative dose of 1.3 Gy and a dose of 26.1 mGy per image. Potential biomedical applications of the imaging system will include projection imaging that requires any of the extracted elements as a contrast agent and multi-contrast K-edge imaging.

Trafficking mechanism of bone marrow-derived mesenchymal stem cells toward hepatocellular carcinoma HepG2 cells by modulating Endoglin, CXCR4 and TGF-ß.

Mesenchymal stem cells (MSCs) display differential migration ability toward different tumor-released factors. Migration of MSCs is highly important in induction of proliferation and invasiveness of hepatocellular carcinoma (HepG2) cells. In this study, the role of CXCR4/CXCL12 axis and TGF-ßR signaling were evaluated in the migration of MSCs toward HepG2 cells. The MSCs were incubated with SDF-1α (CXCL12), antagonists of CXCR4, TGF-ßR, and co-receptor of TGF-ß, (endoglin) for 48h. Then, the migration of these cells toward HepG2 cells was analyzed using in vitro migration assay. SDF-1α at a concentration of 100nM MSCs revealed the highest migration rate toward the conditioned medium (1.62 fold compared to the migration of un-treated MSCs; p<0.05). Applying combination of the antagonists against CXCR4, TGF- ßR, and co-receptor of TGF-ß decreased the migration rate significantly (4.51 fold; p<001). Western blot analysis confirmed that RhoA activity is a core modulator in migration pathway. This study demonstrated that CXCR4 and TGF-ßR signaling are important for migration of MSCs toward HepG2 cells. Identifying the key mediators in the migration of MSCs toward hepatocellular carcinoma cells and then development of the therapeutic inhibitors against these factors can be considered as an essential strategy in suppression of tumor progression and metastasis.

PPAR-gamma in overcoming kinase resistance in chronic myeloid leukemia.

Peroxisome proliferator-activated receptor gamma (PPARγ) plays key roles in regulating cellular differentiation, proliferation and apoptosis pathways. As such, they are considered promising targets for anticancer drug development, especially for breast cancer, multiple myeloma and hematologic malignancies. Chronic myeloid leukemia (CML) is a myeloproliferative disorder arising from an oncogenic Bcr-Abl tyrosine kinase. Inhibitors of this oncogene by small molecules such as imatinib are effective only in 75% of the patient's population. One of the potential strategies to overcome this resistance is to devise combination therapy protocols with other therapeutic agents including PPAR ligands. Since PPAR ligands are potentially interesting in different hematologic malignancies, this article will review the potential of PPAR ligands for use in CML treatment.

Enhanced Cellular Cytotoxicity and Antibacterial Activity of 18-ß-Glycyrrhetinic Acid by Albumin-conjugated PLGA Nanoparticles.

The aim of the present work was to encapsulate 18-ß-Glycyrrhetinic acid (GLA) in albumin conjugated poly(lactide-co-glycolide) (PLGA) nanoparticles by a modified nanoprecipitation method. Nanoparticles (NPs) were prepared by different drug to polymer ratios, human serum albumin (HSA) content, dithiothreitol (as producer of free thiol groups) content, and acetone (as non-solvent in nanoprecipitation). NPs with a size ranging from 126 to 174 nm were achieved. The highest entrapment efficiency (89.4±4.2%) was achieved when the ratio of drug to polymer was 1:4. The zeta potential of NPs was fairly negative (-8 to -12). Fourier transform infrared spectroscopy and differential scanning calorimetry proved the conjugation of HSA to PLGA NPs. In vitro release profile of NPs showed 2 phases: an initial burst for 4 h (34-49%) followed by a slow release pattern up to the end. The antibacterial effects of NPs against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa were studied by microdilution method. The GLA-loaded NPs showed more antibacterial effect than pure GLA (2-4 times). The anticancer MTT test revealed that GLA-loaded NPs were approximately 9 times more effective than pure GLA in Hep G2 cells.

Differential effects of peroxisome proliferator-activated receptor agonists on doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in tumor cells is still a main obstacle for the chemotherapeutic treatment of cancers. Therefore, identification of safe and effective MDR reversing compounds with minimal adverse side effects is an important approach in the cancer treatment. Studies show that peroxisome proliferator-activated receptor (PPARs) ligands can inhibit cell growth in many cancers. Here, we investigated the effect of different PPAR agonists include fenofibrate, troglitazone and aleglitazar on doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. The effects of doxorubicin (DOX) following treatment with PPAR agonists on cell viability were evaluated using MTT assay and the reversal fold (RF) values. Rhodamine123 (Rh123) assays were used to determine P-gp functioning. P-gp mRNA/protein expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis after incubation with troglitazone and aleglitazar. Our results showed that troglitazone and aleglitazar significantly enhanced the cytotoxicity of DOX and decreased the RF values in K562/DOX cells, however, no such results were found for fenofibrate. Troglitazone and aleglitazar significantly down regulated P-gp expression in K562/DOX cells; in addition, the present study revealed that aleglitazar elevated intracellular accumulation of Rh123in K562/DOX cells as short-term effects, which also contribute to the reversal of MDR. These findings show that troglitazone and especially aleglitazar exhibited potent effects in the reversal of P-gp-mediated MDR, suggesting that these compounds may be effective for combination therapy strategies and circumventing MDR in K562/DOX cells to other conventional chemotherapeutic drugs.

Development and Evaluation of a Cetuximab-based Humanized Single Chain Antibody Against EGFR-overexpressing Tumors.

Production of humanized single chain antibodies (hscFv) can potentially be a powerful solution to limitations imposed by large size and murine nature of cetuximab. The present study describes generation of a cetuximab-based hscFv using CDR-grafting method. Cetuximab CDRs were grafted on frameworks selected from human germline antibody sequence repertoire. The strategy employed in selecting human sequences was the highest sequence similarity of variable domains between human and parental antibodies as well as similarity in the CDRs canonical structures. To maintain the binding affinity, the parental vernier zone residues were retained murine in hscFv. Recombinant hscFv was expressed in E. coli and affinity purified by Ni-NTA column. The potency of hscFv in targeting EGFR was evaluated using A431, a cell line over-expressing EGFR. Dot blot and ELISA tests were used to assess the reactivity and MTT assay to evaluate the growth inhibition of hscFv on A431 cell line. The humanization of cetuximab variable regions resulted in 22.2% increase in humanness of hscFv. Reactivity analyses of hscFv on A431 cells showed better binding affinity and higher growth inhibition effect (2.6 times) comparing to murine counterpart. In conclusion, hscFv produced in this study displayed reduced potential immunogenicity as well as enhanced cytotoxic effect on EGFR- overexpressing tumor cells.

The effects of Ramadan fasting on endothelial function in patients with cardiovascular diseases.

BACKGROUND/OBJECTIVES: Endothelial dysfunction, which can be manifested by loss of nitric oxide bioavailability, is an increasingly recognized cause of cardiovascular diseases. Previous studies showed that diets affect endothelial function and modify cardiovascular risks. This study aimed to assess the effects of Ramadan fasting, as a diet intervention, on endothelial function. SUBJECTS/METHODS: The study population consisted of 21 male patients (mean age: 52±9 years) with cardiovascular risks (coronary artery disease, cerebrovascular or peripheral arterial diseases). The biochemical variables in serum of patients were measured 2 days before and after Ramadan fasting. The levels of asymmetric dimethylarginine (ADMA) and vascular endothelial growth factor (VEGF) were evaluated using the enzyme-linked immunosorbent assay. Nitric oxide (NO) and Malondialdehyde (MDA) levels were measured by the Griess and thiobarbituric acid reaction substances assay, respectively. RESULTS: NO levels in patients after Ramadan fasting were significantly higher compared with the baseline value (85.1±11.54 vs 75.8±10.7 µmol/l) (P<0.05). Post-Ramadan levels of ADMA decreased significantly in comparison with pre-Ramadan levels (802.6±60.9 vs 837.6±51.0 nmol/l) (P<0.05). In addition, the levels of VEGF and MDA changed during Ramadan fasting, but these changes were not statistically significant (228.1±27.1 vs 222.7±22.9 pg/ml and 3.2±0.7 vs 3.6±1.1 µmol/l, respectively). CONCLUSIONS: Ramadan fasting may have beneficial effects on endothelial function and can modulate cardiovascular risks. Further studies are needed to confirm the clinical significance of Ramadan fasting on cardiovascular health.

Spectral K-edge subtraction imaging.

We describe a spectral x-ray transmission method to provide images of independent material components of an object using a synchrotron x-ray source. The imaging system and process is similar to K-edge subtraction (KES) imaging where two imaging energies are prepared above and below the K-absorption edge of a contrast element and a quantifiable image of the contrast element and a water equivalent image are obtained. The spectral method, termed 'spectral-KES' employs a continuous spectrum encompassing an absorption edge of an element within the object. The spectrum is prepared by a bent Laue monochromator with good focal and energy dispersive properties. The monochromator focuses the spectral beam at the object location, which then diverges onto an area detector such that one dimension in the detector is an energy axis. A least-squares method is used to interpret the transmitted spectral data with fits to either measured and/or calculated absorption of the contrast and matrix material-water. The spectral-KES system is very simple to implement and is comprised of a bent Laue monochromator, a stage for sample manipulation for projection and computed tomography imaging, and a pixelated area detector. The imaging system and examples of its applications to biological imaging are presented. The system is particularly well suited for a synchrotron bend magnet beamline with white beam access.

The effect of lauryl capping group on protein release and degradation of poly(D,L-lactic-co-glycolic acid) particles.

The aim of this study was to investigate the effect of a specific and frequently used end group (lauryl alcohol) on the protein release and degradation kinetics of poly(DL-lactic-co-glycolic acid) particles of different sizes. Lauryl-capped PLGA and uncapped PLGA (referred to as PLGA-capped and PLGA-COOH, respectively) particles (0.3, 1 and 20 µm) were prepared by a double emulsion solvent evaporation technique. Bovine serum albumin (BSA) was used as a model protein for release studies. During degradation (PBS buffer, pH7.4 at 37°C), a slower dry mass loss was observed for 0.3 µm particles than for particles of 1 and 20 µm. It was further shown that PLGA-capped particles showed slower mass loss likely due to its more hydrophobic nature. It was found that the ester bond hydrolysis rate was substantially slower for PLGA-capped particles and that the rate increased with particle size. Particles showed enrichment in lactic acid content (and thus a decrease in glycolic acid content) in time, and interestingly PLGA-capped particles showed also an enrichment of the lauryl alcohol content. No difference was observed in degradation kinetics between BSA loaded and blank particles. Independent of size, PLGA-COOH based particles showed, after a small burst, a sustained and nearly complete release of BSA during 60-80 days. On the other hand, particles based on PLGA-capped showed a much slower release and exhibited incomplete release, accompanied by the presence of an insoluble residue remaining even after 180 days. FTIR analysis of this residue showed that it contained both polymer and protein. Considering the polymer enrichment in lauryl alcohol, the incomplete release observed for PLGA-capped is likely attributed to interactions between the protein and the lauryl end group. In conclusion, since PLGA-COOH, in contrast to the capped derivative, shows complete degradation as well as quantitative release of an entrapped protein, this polymer is preferred for the design of protein formulations.

Mechanistic studies on the degradation and protein release characteristics of poly(lactic-co-glycolic-co-hydroxymethylglycolic acid) nanospheres.

The purpose of this study was to gain mechanistic insights into the effect of different formulation parameters on the degradation and release behavior of protein-loaded nanoparticulate carrier systems based on an aliphatic polyester with pendant hydroxyl groups, poly(lactic-co-glycolic-hydroxymethyl glycolic acid) (pLGHMGA). Bovine serum albumin (BSA) was used as a model protein. BSA-loaded pLGHMGA nanospheres of 400-700 nm were prepared using a solvent evaporation method using pLGHMGA of different molecular weights and different compositions. Also, the concentration of pLGHMGA in the organic phase was varied. The nanospheres showed a continuous mass loss accompanied by continuous decrease in number average molecular weight, which indicates that the degradation of the nanospheres is by bulk degradation with a rapid release of water-soluble low molecular weight fragments. On the basis of NMR analysis, it is concluded that intramolecular transesterification precedes extensive hydrolysis of the polymer and degradation of the nanospheres. BSA-loaded freeze-dried nanospheres showed a significant burst release of 40-50% of the BSA loading. In contrast, nonfreeze-dried samples showed a small burst of around 10-20%, indicating that freeze-drying induced pore formation. Nonlyophilized nanospheres prepared from pLGHMGA with 64/18/18 lactic/glycolic/hydroxymethylglycolic acid (L/G/HMG) ratio showed a relatively fast release of BSA for the next 30 days. Nanospheres prepared from a more hydrophobic pLGHMGA (74/13/13, L/G/HMG) showed a two-phase release. Circular dichroism analysis showed that the secondary structure of the released protein was preserved. This study shows a correlation between release behavior and particle erosion rate, which can be modulated by the copolymer composition.

Prodigiosin, the red pigment of Serratia marcescens, shows cytotoxic effects and apoptosis induction in HT-29 and T47D cancer cell lines.

In this study, a red pigment of Serratia marcescens PTCC 1111 was purified and identified for antiproliferative activities in HT-29 and T47D cancer cell lines. (1)H-NMR spectroscopy and LC/MS analysis confirmed prodigiosin structure. The antiproliferative effects of prodigiosin were determined by employing the MTT assay. The changes in cell cycle pattern were studied with 4',6-diamidino-2-phenylindole (DAPI) reagent using flow cytometry assay, and Annexin V-PI method was used for apoptotic analysis. Results of MTT assay showed that HT-29 cells were more sensitive to prodigiosin than T47D cells. Prodigiosin-treated HT-29 cells showed increase in S phase and decrease in G2/M, but treated T47D cells showed cell cycle pattern relatively similar to Roswell Park Memorial Institute medium (RPMI). Apoptotic effect of prodigiosin was higher than doxorubicin in HT-29 cells. The data reported here indicate that prodigiosin is a promising antineoplastic agent that triggers apoptosis in different cancer cell lines.

Biopreservation of hamburgers by essential oil of Zataria multiflora.

Hamburgers with high nutrient supply and a loosely-packed structure present favourable conditions for microbial growth. In this study, the chemical composition and antimicrobial activity of the essential oil of Zataria multiflora and its potential application as a natural preservative in reducing the indigenous microbial population of hamburgers were investigated. Carvacrol, thymol and linalool were found to be the most abundant constituents of the essential oil using GC-MS analysis. The essential oil exhibited strong antibacterial activity against Gram-positive and Gram-negative bacteria. Addition of Z. multiflora essential oil in concentrations higher than MIC values influenced the microbial population of hamburgers stored at 25°C, 4°C and -12°C. The significant results of this study are our observations that the use of Z. multiflora essential oil at 0.05% v/w increases the time needed for the natural microflora of hamburgers to reach concentrations able to produce a perceivable spoilage at refrigerator and room temperatures without any inverse effect on their sensory attributes. Freezing of essential oil-treated hamburgers may also reduce the risk of diseases associated with consumption of under-cooked hamburgers through significant microbial reduction by more than 3 log.

Effect of probiotication on antioxidant and antibacterial activities of pomegranate juices from sour and sweet cultivars.

There is an increasing interest in using pomegranate juice as a natural antioxidant rather than synthetic compounds. In this study, the antioxidant capacities of probioticated and nonprobioticated aril juices of sweet (SWV) and sour (SV) pomegranate cultivars were determined by two different methods: ferric reducing antioxidant power (FRAP) and 1,1-diphenyl 2-picrylhydrazyl assay. Total counts of Lactobacillus casei GG increased by about 3 log in SWV and 2 log in SV juices after incubation for 48 h. Probiotication improved the antioxidant activity of SWV juice from 74.4% to 91.82%, and SV juice from 82.64% to 97.8%. Based on the FRAP value, the reducing power of the probioticated pomegranate juices was also much stronger than the nonprobioticated juices. The FRAP values for SWV and SV probioticated juices were 97.34 and 120.7 mmol L(-1), respectively, which were notably higher than 85.87 and 93.4 mmol L(-1) for SWV and SV nonprobioticated juices. Both fermentated and nonfermentated juices exhibited a potent and wide-spectrum antibacterial effect, with the highest activity against Pseudomonas aeruginosa. SV juice showed wider zones of growth inhibition. The results of this study verify for the first time that probiotication of SWV and SV pomegranate juices can add to their beneficial antioxidant activities.

Antimicrobial activity of different Lactobacillus species against multi- drug resistant clinical isolates of Pseudomonas aeruginosa.

BACKGROUND: Lactobacilli are the well known friendly bacteria for their probiotic activities against pathogens. The inhibitory activity of different strains of lactobacilli either obtained as commercial products or isolated from human feces was investigated against the clinical isolates of Pseudomonas aeruginosa. The isolates were selected as the most resistant strains when challenged with anti-pseudomonal antibiotics already in clinical practice. MATERIALS AND METHODS: Both the plate spot test as well as the agar cup method were used for screening of Lactobacillus strains against Pseudomonas aeruginosa. RESULTS: A Lactobacillus acidophilus strain isolated from feces of an Iranian child showed a strong anti-pseudomonal activity (90 percent after 72h incubation) against the multi-drug resistant clinical isolates while a Lactobacillus reuteri strain isolated from a commercial oral product resulted in relatively weak response and a Lactobacillus acidophilus strain isolated from a commercial vaginal product did not show any inhibitory activity. In a kinetic study the lactobacillus sensitive Pseudomonas aeruginosa showed a significant bacteriostatic activity in vitro in the presence of lactobacillus supernatants. CONCLUSION: Some lactobacilli exhibit significant inhibitory activity against the multidrug resistant clinical isolates of Pseudomonas aeruginosa.

Synthesis and cloxacillin antimicrobial enhancement of 2-methylsulfonylimidazolyl-1,4-dihydropyridine derivatives.

BACKGROUND AND THE PURPOSE OF THE STUDY: Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been a major problem worldwide in chemotherapy of infection disease. This study was designed to assess the enhancing effects of a new group of dihydropyridine-3,5dicarboxamides, in combination with cloxacillin with distinctly different mechanisms of action against MRSAs. MATERIAL AND METHODS: Dihydropyridine-3,5-dicarboxamides with 2-methylsulfonylimidazole at 4 position 6a-k were synthesized by the reaction of corresponding aldehyde 5 with different N-aryl acetoacetamides 3 in the presence of ammonium hydroxide. Agar disc diffusion method was used to determine the antibacterial and potentiating activity of different synthetic compounds in the presence and absence of cloxacillin to evaluate their activity as modulators of multidrugresistant (MDR). RESULTS AND MAJOR CONCLUSION: The antibacterial effect of cloxacillin was enhanced by compounds 6g and 6h against cloxacillin-resistant strains (MRSA(1) and MRSA(2)). The potentiation was found 1 2 to be statistically significant (p<0.01). Compound 6g at concentration of 1000 µg/disc, caused a 329 percent potentiation of the activity of cloxacillin against MRSA(1).

Synthesis and antimicrobial effects of silver nanoparticles produced by chemical reduction method.

BACKGROUND AND THE PURPOSE OF THE STUDY: The most prominent nanoparticles for medical uses are nanosilver particles which are famous for their high anti-microbial activity. Silver ion has been known as a metal ion that exhibit anti-mold, anti-microbial and anti-algal properties for a long time. In particular, it is widely used as silver nitrate aqueous solution which has disinfecting and sterilizing actions. The purpose of this study was to evaluate the antimicrobial activity as well as physical properties of the silver nanoparticles prepared by chemical reduction method. METHODS: Silver nanoparticles (NPs) were prepared by reduction of silver nitrate in the presence of a reducing agent and also poly [N-vinylpyrolidone] (PVP) as a stabilizer. Two kinds of NPs were synthesized by ethylene glycol (EG) and glucose as reducing agent. The nanostructure and particle size of silver NPs were confirmed by scanning electron microscopy (SEM) and laser particle analyzer (LPA). The formations of the silver NPs were monitored using ultraviolet- visible spectroscopy. The anti-bacterial activity of silver NPs were assessed by determination of their minimum inhibitory concentrations (MIC) against the Gram positive (Staphylococcus aureus and Staphylococcus epidermidis) as well as Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. RESULTS AND CONCLUSION: The silver nanoparticles were spherical with particle size between 10 to 250 nm. Analysis of the theoretical (Mie light scattering theory) and experimental results showed that the silver NPs in colloidal solution had a diameter of approximately 50 nm. Both colloidal silver NPs showed high anti-bacterial activity against Gram positive and Gram negative bacteria. Glucose nanosilver colloids showed a shorter killing time against most of the tested bacteria which could be due to their nanostructures and uniform size distribution patterns.

Live and heat-inactivated lactobacilli from feces inhibit Salmonella typhi and Escherichia coli adherence to Caco-2 cells.

A quantitative approach has been proposed to evaluate the competitive inhibition of Escherichia coli and Salmonella typhi by live and heat-inactivated laboratory isolated Lactobacillus sp. on adhesion to monolayer of Caco-2 cells. Three species of Lactobacillus (L. casei, L. acidophilus, L. agilis) isolated from human neonate feces and two commercial probiotic strains (L. casei, L. acidophilus) have been compared for probiotic activity. All lactobacilli were able to attach to the Caco-2 cells, however, the degree of adhesion was bacterial strain-dependent. The adhesion indices of the two commercial probiotic strains were not significantly different from the values obtained for the other two similar fecal strains (p > 0.01). The inhibition of attachment of the pathogenic bacteria by inactivated cells of fecal L. acidophilus was examined and compared to the results of live bacteria. The inhibition pattern was similar for live and heat-inactivated L. acidophilus (p > 0.01). The number of attached pathogenic bacteria to the Caco-2 cells decreased when the number of L. acidophilus increased from 10(6) to 10(9) CFU/mL. The heat-inactivated L. acidophilus displayed similar probiotic activity compared to the live bacteria.