Biphasic response of ciprofloxacin in human fibroblast cell cultures

Aloe vera and ofloxacin incorporated chitosan hydrogels show antibacterial activity, stimulate angiogenesis and accelerate wound healing in full thickness rat model

Burns are potentially fatal and physically debilitating injuries, causing psychological and physical scars and result in chronic disabilities. A well vascularized wound bed is required to achieve complete and scar free wound closure. For many centuries, a variety of herbal plants have been used for wound healing, among these aloe vera (AV) has been found to be very effective in wound healing. Secondly, the main reason for delayed wound healing is bacterial infections. Ofloxacin (OX) has been reported as an active antibacterial drug for topical infections and it is effective against both positive and negative bacterial strains. In current research three different concentrations of OX (0.5, 2.5, and 5 mg) were loaded into chitosan (CS)/AV based hydrogels prepared by freeze gelation. The surface morphology of prepared CS/AV based OX loaded hydrogels were evaluated by scanning electron microscopy (SEM). In drug release analysis, 0.5 mg OX loaded hydrogel showed a sustained drug release behavior over 3 days period. An effective dose dependent antibacterial activity was exhibited by OX loaded hydrogels. Alamar Blue cells viability assay revealed that 0.5 mg OX hydrogel (CA 0.5 OX) showed comparatively better 3 T3 fibroblast cells proliferation as compared to CA 2.5 OX (2.5 mg OX) and CA 5 OX hydrogel (5 mg OX). Moreover, all OX loaded hydrogels showed good angiogenic activity in CAM bioassay while higher angiogenic potential was observed from CA 0.5 OX containing comparatively lower concentration of OX. These OX incorporated CS/AV based hydrogels are promising wound dressings for future clinical use.

Ciprofloxacin-Releasing ROS-Sensitive Nanoparticles Composed of Poly(Ethylene Glycol)/Poly(D,L-lactide-co-glycolide) for Antibacterial Treatment

Since urinary tract infections (UTIs) are closely associated with oxidative stress, we developed ROS-sensitive nanoparticles for ciprofloxacin (CIP) delivery for inhibition of UTI. Poly(D,L-lactide-co-glycolide) (PLGA)- selenocystamine (PLGA-selenocystamine) conjugates were attached to methoxypoly(ethylene glycol) (PEG) tetraacid (TA) (TA-PEG) conjugates to produce a copolymer (abbreviated as LGseseTAPEG). Selenocystamine linkages were introduced between PLGA and TA to endow reactive oxygen species (ROS) sensitivity to nanoparticles. CIP-incorporated nanoparticles of LGseseTAPEG copolymer were fabricated by W/O/W/W emulsion method. CIP-incorporated nanoparticles responded to H₂O₂ and then their morphologies were disintegrated by incubation with H₂O₂. Furthermore, particle size distribution of nanoparticles was changed from mono-modal distribution pattern to multi-modal distribution pattern by addition of H₂O₂. CIP release from nanoparticles of LGseseTAPEG copolymer was faster in the presence of H₂O₂ than in the absence of it. In antibacterial study using Escherichia coli (E. coli), free CIP and free CIP plus empty nanoparticles showed dose-dependent inhibitory effect against growth of bacteria while CIP-incorporated nanoparticles have less antibacterial activity compared to free CIP. These results were due to that CIP-incorporated nanoparticles have sustained release properties. When free CIP or CIP-incorporated nanoparticles were introduced into dialysis membrane to mimic in vivo situation, CIP-incorporated nanoparticles showed superior antibacterial activity compared to free CIP. At cell viability assay, nanoparticles of LGseseTAPEG copolymer have no acute cytotoxicity against L929 mouse fibroblast cells and CCD986sk human skin fibroblast cells. We suggest LGseseTAPEG nanoparticles are a promising candidate for CIP delivery.

Naringin sensitizes the antibiofilm effect of ciprofloxacin and tetracycline against Pseudomonas aeruginosa biofilm

The study aims to explore the combinatorial effect of naringin with antibiotics, ciprofloxacin and tetracycline on Pseudomonas aeruginosa biofilms. The antibiofilm efficacy of selected treatment regimes against P. aeruginosa biofilm were quantified by crystal violet assay, MTT assay, Congo red binding assay, and were visualized by confocal laser scanning microscopy and scanning electron microscopy. All the assays reflected antibiofilm activities, however, combinatorial performances of naringin with antibiotics were found to be more significant. A significant reduction in swimming and swarming motilities along with pellicle formation and altered colony morphology were observed as a result of combinatorial effect. The cytotoxicity of naringin and its antibiotic combinations was assayed on murine macrophage cell line. The applicability of such combinations was tested for their relative eradication against pre-formed biofilm on urinary catheter surface. This finding indicated that naringin potentiates the efficacy of both ciprofloxacin and tetracycline on P. aeruginosa biofilm in comparison to their solo treatment. The finding would help to open hitherto unexplored possibilities of establishing naringin as a potential antibiofilm agent and suggest on the possibility of its use in drug-herb combinations for managing biofilm-associated bacterial infections.

Novel Segmented Concentration Addition Method to Predict Mixture Hormesis of Chlortetracycline Hydrochloride and Oxytetracycline Hydrochloride to Aliivibrio fischeri

Hormesis is a concentration-response phenomenon characterized by low-concentration stimulation and high-concentration inhibition, which typically has a nonmonotonic J-shaped concentration-response curve (J-CRC). The concentration addition (CA) model is the gold standard for studying mixture toxicity. However, the CA model had the predictive blind zone (PBZ) for mixture J-CRC. To solve the PBZ problem, we proposed a segmented concentration addition (SCA) method to predict mixture J-CRC, which was achieved through fitting the left and right segments of component J-CRC and performing CA prediction subsequently. We selected two model compounds including chlortetracycline hydrochloride (CTCC) and oxytetracycline hydrochloride (OTCC), both of which presented J-CRC to Aliivibrio fischeri (AVF). The seven binary mixtures (M1-M7) of CTCC and OTCC were designed according to their molar ratios of 12:1, 10:3, 8:5, 1:1, 5:8, 3:10, and 1:12 referring to the direct equipartition ray design. These seven mixtures all presented J-CRC to AVF. Based on the SCA method, we obtained mixture maximum stimulatory effect concentration (ECm) and maximum stimulatory effect (Em) predicted by SCA, both of which were not available for the CA model. The toxicity interactions of these mixtures were systematically evaluated by using a comprehensive approach, including the co-toxicity coefficient integrated with confidence interval method (CTCICI), CRC, and isobole analysis. The results showed that the interaction types were additive and antagonistic action, without synergistic action. In addition, we proposed the cross point (CP) hypothesis for toxic interactive mixtures presenting J-CRC, that there was generally a CP between mixture observed J-CRC and CA predicted J-CRC; the relative positions of observed and predicted CRCs on either side of the CP would exchange, but the toxic interaction type of mixtures remained unchanged. The CP hypothesis needs to be verified by more mixtures, especially those with synergism. In conclusion, the SCA method is expected to have important theoretical and practical significance for mixture hormesis.

Disparate effects of antibiotic-induced microbiome change and enhanced fitness in Daphnia magna

It is a common view that an organism’s microbiota has a profound influence on host fitness; however, supporting evidence is lacking in many organisms. We manipulated the gut microbiome of Daphnia magna by chronic exposure to different concentrations of the antibiotic Ciprofloxacin (0.01–1 mg L^-1), and evaluated whether this affected the animals fitness and antioxidant capacity. In line with our expectations, antibiotic exposure altered the microbiome in a concentration-dependent manner. However, contrary to these expectations, the reduced diversity of gut bacteria was not associated with any fitness detriment. Moreover, the growth-related parameters correlated negatively with microbial diversity; and, in the daphnids exposed to the lowest Ciprofloxacin concentrations, the antioxidant capacity, growth, and fecundity were even higher than in control animals. These findings suggest that Ciprofloxacin exerts direct stimulatory effects on growth and reproduction in the host, while microbiome- mediated effects are of lesser importance. Thus, although microbiome profiling of Daphnia may be a sensitive tool to identify early effects of antibiotic exposure, disentangling direct and microbiome-mediated effects on the host fitness is not straightforward.

GSH depletion, mitochondrial membrane breakdown, caspase-3/7 activation and DNA fragmentation in U87MG glioblastoma cells: New insight into the mechanism of cytotoxicity induced by fluoroquinolones

Fluoroquinolones are a known synthetic group of antibiotics that have been the subject of many research interests. This class of antibiotics was shown to be cytotoxic towards various cancer cell lines, thus representing a potentially important source of new anticancer agents. The present study was designed to examine the effect of ciprofloxacin and moxifloxacin on cell viability, redox balance and apoptosis in U87MG glioblastoma cells. Herein, we found that both fluoroquinolones decrease the viability and exert an anti-proliferative effect on U87MG cells. The EC₅₀ values were found to be as 0.75 µmol/ml, 0.57 µmol/ml, 0.53 µmol/ml for ciprofloxacin and 24, 48, 72 h incubation time, respectively, and 0.48 µmol/ml, 0.22 µmol/ml, 0.15 µmol/ml for moxifloxacin and 24, 48, 72 h incubation time, respectively. Ciprofloxacin and moxifloxacin have also induced the intracellular GSH depletion and apoptosis as shown by externalization of phosphatidylserine, caspase-3/7 activation, S and sub-G₁ cell cycle arrest, nuclear morphological changes induction and DNA fragmentation. The mechanism of apoptosis was related to the loss of mitochondrial membrane potential suggesting activation of the intrinsic mitochondrial pathway. This is the first study that may provide the basis for understanding potential cellular and molecular mechanism underlying ciprofloxacin and moxifloxacin cytotoxic and pro-apoptotic effect towards U87MG glioblastoma cells, suggesting that these fluoroquinolone derivatives may have value for the development as anti-glioma agents.

Protective effect of quercetin in gentamicin-induced oxidative stress in vitro and in vivo in blood cells. Effect on gentamicin antimicrobial activity

We have evaluated the effect of gentamicin and gentamicin plus quercetin on ROS production, endogenous antioxidant defenses (SOD and CAT) and lipid peroxidation in vitro on human leukocytes and in vivo on whole rat blood. Gentamicin generated ROS production in human leukocytes, produced a dual effect on both enzymes dosage-dependent and generated an increase in lipid peroxidation. Quercetin, in leukocytes stimulated by gentamicin, showed more inhibitory capacity in ROS production than the reference inhibitor (vitaminC) in mononuclear cells and a similar protective behavior at this inhibitor in polymorphonuclear cells. Quercetin, in both cellular systems, tend to level SOD and CAT activities, reaching basal values and could prevent lipidic peroxidation induced by gentamicin. The results in Wistar rats confirmed that therapeutic doses of gentamicin can induce oxidative stress in whole blood and that the gentamicin treatment plus quercetin can suppress ROS generation, collaborate with SOD and CAT and diminish lipid peroxidation. Finally, flavonoid and antibiotic association was evaluated on the antimicrobial activity in S. aureus and E. coli, showing that changes were not generated in the antibacterial activity of gentamicin against E. coli strains, while for strains of S. aureus a beneficial effect observes. Therefore, we have demonstrated that gentamicin could induce oxidative stress in human leukocytes and in whole blood of Wistar rats at therapeutic doses and that quercetin may to produce a protective effect on this oxidative stress generated without substantially modifying the antibacterial activity of gentamicin against E. coli strains, and it contributes to this activity against S. aureus strains.

Beneficial effects of quercetin on renal injury and oxidative stress caused by ciprofloxacin in rats: A histological and biochemical study

Ciprofloxacin is a broad-spectrum quinolone antibiotic commonly used in clinical practice. Quercetin is an antioxidant belongs to flavonoid group. It inhibits the production of superoxide anion. In this study, we aimed to evaluate the effects of quercetin on renal injury and oxidative stress caused by ciprofloxacin. Twenty-eight female Wistar albino rats were divided into four groups: control, quercetin (20 mg kg(-1) day(-1) gavage for 21 days), ciprofloxacin (20 mg kg(-1) twice a day intraperitoneally for 10 days), and ciprofloxacin + quercetin. Samples were processed for histological and biochemical evaluations. Malondialdehyde (MDA) and glutathione (GSH) levels, superoxide dismutase (SOD), and catalase (CAT) activities were measured in kidney tissue. The ciprofloxacin group showed histopathological changes such as infiltration, dilatation in tubules, tubular atrophy, reduction of Bowman's space, congestion, hemorrhage, and necrosis. In the ciprofloxacin + quercetin group, these histopathological changes markedly reduced. MDA levels increased in the ciprofloxacin group and decreased in the ciptofloxacin + quercetin group. SOD and CAT activities and GSH levels significantly decreased in the ciprofloxacin group. On the other hand, in the ciprofloxacin + quercetin group, SOD and CAT activities and GSH levels significantly increased with regard to the ciprofloxacin group. We concluded that quercetin has antioxidative and therapeutic effects on renal injury and oxidative stress caused by ciprofloxacin in rats.

Increased release time of antibiotics from bone allografts through a novel biodegradable coating

The use of bone allografts is contraindicated in septic revision surgery due to the high risk of graft reinfection. Antibiotic release from the graft may solve the problem and these combinations can theoretically be used for prevention or even therapy of infection. The present study investigated whether amoxicillin, ciprofloxacin, and vancomycin alone or in combination with chitosan or alginate are suitable for short-term or long-term bone coating. Human bone allografts were prepared from femoral head and lyophilized. Antibiotic coating was achieved by incubating the grafts in antibiotic solution and freeze-drying again. Two biopolymers chitosan and alginate were used for creating sustained-release implantable coatings and the drug release profile was characterized in vitro by spectrophotometry. Using lyophilization with or without chitosan only resulted in short-term release that lasted up to 48 hours. Alginate coating enabled a sustained release that lasted for 8 days with amoxicillin, 28 days with ciprofloxacin coating, and 50 days with vancomycin coating. Using only implantable biodegradable allograft and polymers, a sustained release of antibiotics was achieved with ciprofloxacin and vancomycin for several weeks. Since the calculated daily release of the antibiotic was lower than the recommended IV dose, the calcium alginate coated bone graft can support endoprosthesis revision surgery.

Response to imatinib as a function of target kinase expression in recurrent glioblastoma

BACKGROUND

Despite some progress in the treatment of glioblastoma, most patients experience tumor recurrence. Imatinib mesylate, a tyrosine kinase inhibitor of platelet derived growth factor receptor-alpha and -beta, c-fms, c-kit, abl and arg kinase (imatinib targets), has been shown to prevent tumor progression in early studies of recurrent gliomas, but has shown weak activity in randomized controlled trials. We studied the response to oral imatinib in 24 patients with recurrent glioblastoma who showed immunohistochemical expression of these imatinib targets in the initially resected tumor tissue.

METHODS

We offered oral imatinib, 400 mg once daily treatment to 24 recurrent glioblastoma patients whose initial biopsy showed presence of at least one imatinib inhibitable tyrosine kinase.

RESULTS

Six imatinib treated patients survived over one year. Twelve patients achieved at least tumor stabilisations from 2.6 months to 13.4 months. Median progression free survival was 3 months and median overall survival was 6 months. Imatinib was well tolerated. We found evidence, though not statistically significant, that arg kinase [Abl-2] immunopositivity had shorter survival [5 months] than the arg kinase immunonegative group [9 months].

CONCLUSIONS

Responses to imatinib observed in this patient series where imatinib inhibitable tyrosine kinases were documented on the original biopsy are marginally better than that previously reported in imatinib treatment of unselected recurrent glioblastoma patients. We thus present a suggestion for defining a patient sub-population who might potentially benefit from imatinib.

Ciprofloxacin-collagen conjugate in the wound healing treatment

The synthesis of a novel functional biomaterial for wound healing treatment was carried out by adopting a free-radical grafting procedure in aqueous media. With this aim, ciprofloxacin (CFX) was covalently incorporated into collagen (T1C) chains employing an ascorbic acid/hydrogen peroxide redox pair as biocompatible initiator system. The covalent insertion of CFX in the polymeric chains was confirmed by FT-IR and UV analyses, while an antibacterial assay demonstrated the activity of the synthesized conjugate against Staphylococcusaureus and Escherichia coli, microorganisms that commonly infect wounds. A catechin blended conjugate was also tested in order to evaluate the ability to influence fibroblast cell growth. The observed antibacterial activity and stimulation of fibroblast growth support the applicability of CFX-T1C conjugate in wound treatment encouraging the healing process.

Ciprofloxacin-induced antibacterial activity is reversed by vitamin E and vitamin C

In the present study, we investigated the possible involvement of oxidative stress in ciprofloxacin-induced cytotoxicity against several reference bacteria including Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, and clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA). Oxidative stress was assessed by measurement of hydrogen peroxide generation using a FACScan flow cytometer. The antibacterial activity of ciprofloxacin was assessed using the disk diffusion method and by measuring the minimum inhibitory concentration (MIC). Ciprofloxacin induced a dose-dependent antibacterial activity against all bacteria where the highest tested concentration was 100 ug/ml. Results revealed that E. coli cells were highly sensitive to ciprofloxacin (MIC = 0.21 μg/mL ± 0.087), P. aeruginosa and S. aureus cells were intermediately sensitive (MIC = 5.40 μg/mL ± 0.14; MIC = 3.42 μg/mL ± 0.377, respectively), and MRSA cells were highly resistant (MIC = 16.76 μg/mL ± 2.1). Pretreatment of E. coli cells with either vitamin E or vitamin C has significantly protected cells against ciprofloxacin-induced cytotoxicity. These results indicate the possible antagonistic properties for vitamins C or E when they are used concurrently with ciprofloxacin.

Cytotoxic effect of ciprofloxacin in primary culture of rat astrocytes and protection by Vitamin E

The aim of this study was to investigate the possible cytotoxic and oxidative stress inducing effects of ciprofloxacin (CPFX) on primary cultures of rat astrocytes. The cultured cells were incubated with various concentrations of CPFX (0.5-300mg/l), and cytotoxicity was determined by neutral red (NR) and MTT assays. Survival profile of cells was biphasic in NR assay: CPFX did not cause any alteration at any concentration for 7h, whereas < or =50mg/l concentrations induced significant cell proliferation in incubation periods of 24, 48, 72, and 96h. However, cell proliferation gradually decreased at higher concentrations, and 200 and 300mg/l of CPFX exposure was found to be significantly (p<0.05) cytotoxic at all time periods. With MTT assay, no alteration was noted for incubation period of 7h, as observed with NR assay. But, cell viability decreased with approximately > or =50mg/l CPFX exposure in all other time periods. Cell proliferation was only seen in 24h of incubation with 0.5 and 5mg/l CPFX. Vitamin E pretreatment of cell cultures were found to be providing complete protection against cytotoxicity of 300mg/l CPFX in 96h incubation when measured with both NR and MTT assays. The SOD pretreatment was partially protective with NR assay, but no protection was noted when measured with MTT. A significant enhancement of lipid peroxidation was observed with the cytotoxic concentration of the drug, but total glutathione content and catalase activity of cells did not change. The data obtained in this study suggest that, in accordance with our previous results with fibroblast cells, CPFX-induced cytotoxicity is related to oxidative stress. And the biphasic effect of CPFX possibly resulted from the complex dose-dependent relationships between reactive oxygen species, cell proliferation, and cell viability.