The percutaneous permeation of a combination of 0.1% octenidine dihydrochloride and 2% 2-phenoxyethanol (octenisept®) through skin of different species in vitro

<p>Abstract</p> <p>Background</p> <p>A water based combination of 0.1% octenidine dihydrochloride and 2% 2 - phenoxyethanol is registered in many European countries as an antiseptic solution (octenisept^®) for topical treatment with high antimicrobial activity for human use, but octenidine based products have not been registered for veterinary use yet. The aim of the present study was to investigate whether octenidine dihydrochloride or 2 -phenoxyethanol, the two main components of this disinfectant, permeate through animal skin <it>in vitro</it>. Therefore, permeation studies were conducted using Franz-type diffusion cells. 2 ml of the test compound were applied onto 1.77 cm²split skin of cats, dogs, cows and horses. To simulate wounded skin, cattle skin was treated with adhesive tapes 100 times, as well. Up to an incubation time of 28 hours samples of the acceptor chamber were taken and were analysed by UV-HPLC. Using the method of the external standard, the apparent permeability coefficient, the flux J_max, and the recovery were calculated. Furthermore, the residues of both components in the skin samples were determined after completion of the diffusion experiment.</p> <p>Results</p> <p>After 28 hours no octenidine dihydrochloride was found in the receptor chamber of intact skin samples, while 2.7% of the topical applied octenidine dihydrochloride permeated through barrier disrupted cattle skin. 2 - phenoxyethanol permeated through all skin samples with the highest permeability in equine, followed by bovine, canine to feline skin. Furthermore, both components were found in the <it>stratum corneum </it>and the dermis of all split skin samples with different amounts in the examined species.</p> <p>Conclusion</p> <p>For 2-phenoxyethanol the systemic impact of the high absorption rate and a potential toxicological risk have to be investigated in further studies. Due to its low absorption rates through the skin, octenidine dihydrochloride is suitable for superficial skin treatment in the examined species.</p

Precision-cut bovine udder slices (PCBUS) as an in-vitro-model of an early phase of infection of bovine mastitis

Background The aim of this study was to establish precision-cut bovine udder slices (PCBUS) as an in-vitro-model to investigate pathophysiological processes in the early phase of mastitis in order to have the possibility to investigate new therapeutic approaches for the treatment of such udder inflammation in later studies. Furthermore, this model should contribute to substitute in-vivo-experiments. Bovine mastitis is one of the most common and costly infectious diseases in the dairy industry, which is largely associated with the use of antimicrobial agents. Given this problem of antimicrobial resistance, it is essential to step up research into bacterial infectious diseases. Thus, the transfer of the in-vitro-model of precision-cut tissue slices to the bovine udder enables broad research into new therapeutic approaches in this area and can also be used to address issues in basic research or the characterisation of complex pathophysiological processes. Results A stimulation with LPS, PGN or the combination of both substances (LPS:PGN) demonstrates the ability of the PCBUS to react with a significant secretion of IL-1ß, TNF-α and PGE2. Conclusion The slices represent an instrument for investigating pharmacological interactions with udder tissue, which can be useful for studies on pharmacological questions and the understanding of complex pathophysiological processes of infection and inflammation

Dynamics of distribution and efficacy of different spot-on permethrin formulations in dogs artificially infested with Dermacentor reticulatus

<p>Abstract</p> <p>Background</p> <p>Varying reports concerning the duration and reliability of different permethrin preparations' efficacy can be found in the literature. The aim of this study was to investigate the dynamics of the distribution and efficacy of four different spot-on formulations with permethrin as the active ingredient formulated with different solvents. To examine the influence of these solvents on the speed of distribution and the acaricidal activity of permethrin in the coat, an <it>in vivo </it>study under laboratory conditions was performed. Six dogs per test period were treated with the recommended dose and 1, 14 and 28 days after treatment dogs were infested with <it>Dermacentor reticulatus </it>ticks: a) on the back, near the application site, and b) on the hind leg, the greatest possible distance from the application site. Efficacies were determined 6 hours after tick infestation to examine the repellent effect and the speed of kill of the products which plays an important role in the context of tick transmitted diseases.</p> <p>Results</p> <p>After six hours of exposure, a significant acaricidal efficacy (p < 0.001) could be observed in all treated groups over the whole duration of the study, regardless of which product was used. While the arithmetic mean of attached ticks was < 3 on Day 1, numbers increased over the course of the study to a mean of > 9 on Day 28. However, most of these ticks were dead even 28 days after treatment, as the mean of live attached ticks was still < 2. Significant differences could neither be found between the different permethrin spot-on formulations, nor between the two parts of the body (p > 0.05).</p> <p>Conclusions</p> <p>All products were able to kill ticks within six hours following infestation from Day 1 to Day 28 after treatment. Additionally, no significant difference between the tick numbers on the back and the hind leg could be found at any time, which implies a homogenous distribution of permethrin over the body. The efficacy of all four products was comparable during the whole study period, showing that the different solvents do not significantly affect the dynamics of distribution.</p

Magnesium as a biomaterial and its biological interactions

To investigate different magnesium alloys as a biodegradable material for implants it is necessary to understand the degradation process in the biological environment. The following study shows interactions of pure magnesium with various physical and chemical environmental parameters according to the parameters within the application area.DFG/SFB/599DFG/SFB/59

Increased accumulation of magnetic nanoparticles by magnetizable implant materials for the treatment of implant-associated complications

Background: In orthopaedic surgery, accumulation of agents such as anti-infectives in the bone as target tissue is difficult. The use of magnetic nanoparticles (MNPs) as carriers principally enables their accumulation via an externally applied magnetic field. Magnetizable implants are principally able to increase the strength of an externally applied magnetic field to reach also deep-seated parts in the body. Therefore, the integration of bone-addressed therapeutics in MNPs and their accumulation at a magnetic orthopaedic implant could improve the treatment of implant related infections. In this study a martensitic steel platelet as implant placeholder was used to examine its accumulation and retention capacity of MNPs in an in vitro experimental set up considering different experimental frame conditions as magnet quantity and distance to each other, implant thickness and flow velocity.Results: The magnetic field strength increased to approximately 112% when a martensitic stainless steel platelet was located between the magnet poles. Therewith a significantly higher amount of magnetic nanoparticles could be accumulated in the area of the platelet compared to the sole magnetic field. During flushing of the tube system mimicking the in vivo blood flow, the magnetized platelet was able to retain a higher amount of MNPs without an external magnetic field compared to the set up with no mounted platelet during flushing of the system. Generally, a higher flow velocity led to lower amounts of accumulated MNPs. A higher quantity of magnets and a lower distance between magnets led to a higher magnetic field strength. Albeit not significantly the magnetic field strength tended to increase with thicker platelets.Conclusion: A martensitic steel platelet significantly improved the attachment of magnetic nanoparticles in an in vitro flow system and therewith indicates the potential of magnetic implant materials in orthopaedic surgery. The use of a remanent magnetic implant material could improve the efficiency of capturing MNPs especially when the external magnetic field is turned off thus facilitating and prolonging the effect. In this way higher drug levels in the target area might be attained resulting in lower inconveniences for the patient

Investigation of the pathophysiology of bacterial mastitis using precision-cut bovine udder slices

Mastitis in cattle is a major health problem as well as incurring high costs for the dairy industry. To assess the suitability of precision-cut bovine udder slices (PCBUS) for bovine mastitis studies, we infected PCBUS with 2 different Staphylococcus aureus strains. Accordingly, we investigated both the tissue response to infection based on immune mediators at the mRNA and protein levels and the invasion of bacteria within the tissue. The studied proteins represent immune mediators of early inflammation [IL-1β, tumor necrosis factor-α (TNF-α), prostaglandin E2 (PGE2)] and showed a time-dependent increase in concentration. Infection of PCBUS with S. aureus resulted in increased expression of proinflammatory cytokines and chemokines such as TNF-α, C-C motif chemokine ligand 20 (CCL20), IL-1β, IL-6, and IL-10, but not C-X-C motif chemokine ligand 8 (CXCL8), lingual antimicrobial peptide (LAP), or S100 calcium binding protein A9 (S100A9) at the mRNA level. To compare the data acquired with this model, we carried out investigations on primary bovine mammary epithelial cells. Our results showed that the immune responses of both models - PCBUS and primary bovine mammary epithelial cells - were similar. In addition, investigations using PCBUS enabled us to demonstrate adherence of bacteria in the physiological cell network. These findings support the use of PCBUS in studies designed to further understand the complex pathophysiological processes of infection and inflammation in bovine mastitis and to investigate alternative therapies for mastitis

Effects of ceftiofur treatment on the susceptibility of commensal porcine E.coli – comparison between treated and untreated animals housed in the same stable

Background Healthy farm animals have been found to act as a reservoir of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli). Therefore, the objective of the study was to determine the input of antimicrobial active ceftiofur metabolites in the stable via faeces and urine after intramuscular administration of the drug to pigs and the elucidation of the Escherichia coli ESBL resistance pattern of treated and untreated pigs housed in the same barn during therapy. Methods For determination of the minimal inhibitory concentration (MIC) the method of microdilutionaccording to the recommended procedure of the Clinical and Laboratory Standards Institute was used. Inaddition to that, a qualitative determination was performed by agar dilution. Unsusceptible E. coli speciesselected via agar dilution with cefotaxime were confirmed by MALDI-TOF and ESBL encoding genes wereidentified by PCR. The amounts of ceftiofur measured as desfuroylceftiofur (DFC) in the different probes (plasma, urine, faeces and dust) were analysed by UPLC-MS/MS. Results In a first experiment two groups of pigs (6 animals per group) were housed in the same barn in two separated boxes. One group (group B) were treated with ceftiofur according to the licence (3 mg/kg administered intramuscularly (i.m.) on three consecutive days, day 1–3). During a second treatment period (day 29–31) an increased rate of ESBL resistant E. coli was detectable in these treated pigs and in the air of the stable. Moreover, the second group of animals (group A) formerly untreated but housed for the whole period in the same stable as the treated animals revealed increased resistance rates during their first treatment (day 45–47) with ceftiofur. In order to investigate the environmental input of ceftiofur during therapy and to simulate oral uptake of ceftiofur residues from the air of the stable a second set of experiments were performed. Pigs (6 animals) were treated with an interval of 2 weeks for 3 days with different doses of ceftiofur (3 mg/kg, 1 mg/kg and 0.3 mg/kg i.m.) as well as with 3 mg/kg per os) and the renal and biliary excretion of ceftiofur as its active metabolite were measured in comparison to the plasma levels. In addition to that, probes of the sedimentation dust and the air of the stable were analysed for drug residues. Conclusion The present study shows that treatment of several animals in a stable with ceftiofur influences the resistance pattern of intestinal Escherichia coli of the treated as well as untreated animals housed in the same stable. During therapy with the drug which was administered by injection according to the licence we detected nameable amounts of ceftiofur and its active metabolites in the dust and air of the stable

Biodistribution, biocompatibility and targeted accumulation of magnetic nanoporous silica nanoparticles as drug carrier in orthopedics

Background: In orthopedics, the treatment of implant-associated infections represents a high challenge. Especially, potent antibacterial effects at implant surfaces can only be achieved by the use of high doses of antibiotics, and still often fail. Drug-loaded magnetic nanoparticles are very promising for local selective therapy, enabling lower systemic antibiotic doses and reducing adverse side effects. The idea of the following study was the local accumulation of such nanoparticles by an externally applied magnetic field combined with a magnetizable implant. The examination of the biodistribution of the nanoparticles, their effective accumulation at the implant and possible adverse side effects were the focus. In a BALB/c mouse model (n = 50) ferritic steel 1.4521 and Ti90Al6V4 (control) implants were inserted subcutaneously at the hindlimbs. Afterwards, magnetic nanoporous silica nanoparticles (MNPSNPs), modified with rhodamine B isothiocyanate and polyethylene glycol-silane (PEG), were administered intravenously. Directly/1/7/21/42 day(s) after subsequent application of a magnetic field gradient produced by an electromagnet, the nanoparticle biodistribution was evaluated by smear samples, histology and multiphoton microscopy of organs. Additionally, a pathohistological examination was performed. Accumulation on and around implants was evaluated by droplet samples and histology. Results: Clinical and histological examinations showed no MNPSNP-associated changes in mice at all investigated time points. Although PEGylated, MNPSNPs were mainly trapped in lung, liver, and spleen. Over time, they showed two distributional patterns: early significant drops in blood, lung, and kidney and slow decreases in liver and spleen. The accumulation of MNPSNPs on the magnetizable implant and in its area was very low with no significant differences towards the control. Conclusion: Despite massive nanoparticle capture by the mononuclear phagocyte system, no significant pathomorphological alterations were found in affected organs. This shows good biocompatibility of MNPSNPs after intravenous administration. The organ uptake led to insufficient availability of MNPSNPs in the implant region. For that reason, among others, the nanoparticles did not achieve targeted accumulation in the desired way, manifesting future research need. However, with different conditions and dimensions in humans and further modifications of the nanoparticles, this principle should enable reaching magnetizable implant surfaces at any time in any body region for a therapeutic reason. © 2020 The Author(s)

Magnesium corrosion particles do not interfere with the immune function of primary human and murine macrophages

Magnesium is currently under investigation as a prospective biodegradable implant material. Biodegradation of magnesium causes a release of magnesium, hydroxide ions and hydrogen gas but it can also lead to the formation of particulate debris. Implant-derived particles may have immunotoxic effects. To investigate the influence of magnesium-derived particles on the immune functions of primary macrophages, up to 500 mu g/ml magnesium or magnesium corrosion particles were added to the cell culture medium. No major effects were observed on cell viability and on the release of the proinflammatory cytokine tumor necrosis factor (TNF)alpha. In addition, the ability of macrophages to stimulate proliferation of allogenic lymphocytes in a mixed leukocyte reaction remained unaffected. When macrophages were incubated with magnesium particles and then infected with the apathogenic Mycobacterium smegmatis, infection-induced TNF alpha secretion from murine macrophages was inhibited but not from human macrophages. However, the bactericidal activity of either cell type was not influenced. In conclusion, magnesium-related particles did not restrict the immune function of macrophages, suggesting that magnesium implants and corrosion particles derived thereof are highly biocompatible and have a low inflammatory potential