No description available.

The use of magnesium for degradable implants can fill the need for temporary, load bearing, metallic orthopaedic implants without the risks and expense of further surgeries once the bone has healed. Mg is non toxic and biocompatible, but the corrosion rate in the body is too high. The rate will need to be moderated if these implants are to be made clinically useful. A review of common orthopaedic coatings found that the biomimetic calcium phosphate coating process meets the criteria for a good coating. This process was designed for permanent implants, and its corrosion protection properties were unknown on Mg. The research presented here evaluates and optimizes aspects of the corrosion protection of biomimetic coatings in vitro. To accurately identify the corrosion mechanisms of such coatings, the in vitro behaviour of several common simulated body fluids and buffer systems was evaluated. The deposition of biomimetic coatings on Mg was compared to Ti. The effect of common surface treatments on the deposition, composition, and ultimate corrosion protection was identified in order to understand the corrosion properties of these coatings. Following the results, the biomimetic method was modified to optimize the protection by reducing the defects. The corrosion properties of these modified coatings were assessed in vitro. The limitation of the biomimetic coatings was found to be in all cases sensitive to the defects present in the coating. While these could be minimized, they were not eliminated. This led to unfavourable corrosion properties. To solve this problem, a novel treatment was developed to give the biomimetic coatings self-healing properties. This treatment promoted local repair in the coating at the defects, greatly improving the corrosion properties. The in vitro model was increased in complexity by adding first amino acids, then proteins. The corrosion behaviour of the coatings was compared in these solutions to understand the effects of these molecules. The data gathered will help to build a better model of in vivo corrosion, and allow better prediction of the performance of biomimetic coatings for corrosion resistance.

Pedicle screw-rod instrumentation is considered a standard treatment for spinal instability, and titanium is the most common material for this application. Cobalt-chromium has several advantages over titanium and is generating interest in orthopedic practice. The aim of this study was to compare titanium versus cobalt-chromium rods in posterior fusion, with and without transverse connectors, through in vitro biomechanical testing and determine the optimal configuration. Six cadaveric lumbar spines (L1-S1) were used. Posterior and middle column injuries were simulated at L3-L5 and different pedicle screw constructs were implanted. Specimens were subjected to flexibility tests and range of motion, intradiscal pressure and axial rotation energy loss were statistically compared among the following conditions: intact, titanium rods (without transverse connectors), titanium rods with transverse connectors, cobalt-chromium rods (without transverse connectors) and cobalt-chromium rods with transverse connectors. The novel measurement of energy loss was examined to determine its viability in fusion investigations. All fusion constructs significantly (p0.05) were observed in axial rotation among all conditions. Intradiscal pressure significantly increased (p≤0.01) after fusion, except for the cobalt-chrome conditions in extension (p≥0.06), and no significant differences (p>0.99) were found among fixation constructs. Energy loss, differences became significant between the cobalt-chrome with transverse connector condition with respect to the cobalt-chrome (p=0.05) and titanium (p There is not enough evidence to support that the cobalt-chrome rods performed biomechanically different than the titanium rods. The use of titanium rods may be more beneficial because there is a lower probability of corrosion. The inclusion of the transverse connector only increased stability for the cobalt-chromium construct in axial rotation, which suggests that it is beneficial in complete facetectomy procedures.

The driving force behind this thesis was the need for developing tissue mimicking materials that can mimic the dielectric properties of various biological soft tissues to aid in the development and testing of electromagnetic medical devices. Materials that can mimic the dielectric properties of human skin, adipose, muscle, malignant and healthy fibroglandular tissue, liver, pancreas, and kidney within the frequency range of 500 MHz to 20 GHz have been characterized and tested. The tissue mimicking materials are used to construct biological phantoms for studies that involve the investigation of wireless medical telemetry and a microwave breast cancer detection device.

No description available.

<p>Otitis media with effusion (OME) is the major form of chronic relapsing inflammatory disease of the middle ear, constitutes the most common diagnosis for children under 15 years old and is the major cause of auditory dysfunction in pre-school children. OME is a disease more commonly found in allergic children. These studies sought to investigate the inflammatory response in the middle ear of patients and test the hypothesis that an allergic-like response might occur in the ear. Atopy was diagnosed by standard in vitro tests. Immunochemical techniques used to study classic allergic rhinitis and asthma were extrapolated to the evaluation of OME children whose effusion persisted beyond 2 months. Not only eosinophil cationic protein (ECP), tryptase, CD3-positive and IL-5 producing cells, but also myeloperoxidase (MPO) was found in middle ear fluid and/or mucosa in the majority of patients with OME and atopy. </p><p>Initially, levels of ECP, MPO, and tryptase were measured in effusions from 97 random OME patients whose atopic status was determined by in vitro testing to 12 inhalants and 5 foods. The response of eosinophils, neutrophils and mast cells in the middle ear was distinctly different between atopic and non-atopic patients (p<0.001) with higher levels of the cell markers in the atopic group of patients. This suggested that 1) perhaps OME was predominantly a disease of atopics and that 2) they differed in their response from non-atopics.</p><p>Tryptase was measured in middle ear effusions from 38 patients with OME, 94.7% of whom were atopic by in vitro testing. Tryptase was elevated only in the effusion of atopic patients as compared to 5 controls (p<0.01). Biopsies stained histochemically for tryptase showed evidence of mast cells in the mucosa and submucosa from 6 of 8 OME ears but absent in 4 normals.</p><p>Middle ear biopsies, embedded in a plastic resin to improve the structural preservation, from 5 patients with OME and 5 normals were evaluated for the presence of eosinophils and neutrophils with monoclonal antibodies against 4 specific granule proteins. Eosinophils and neutrophils were present in the mucosa and mucus in significantly higher numbers than in the control group.</p><p>In an effort to determine whether the middle ear itself might be involved in allergic disease, evidence that some of the cells, mediators and cytokines associated specifically with a Th-2 response were sought for in the middle ear mucosa of these children. Middle ear biopsies from 7 atopic patients with OME and 4 controls demonstrated the presence of activated eosinophils, CD-3+ T cells and IL-5 mRNA cells only in the mucosa from atopic OME children. </p><p>Conclusion: Effusion and mucosal biopsies containing ECP, tryptase, and/or IL-5 mRNA cells, CD3+ T cells, eosinophils, and mast cells indicate that many of the mediators and cells essential to the production of a Th-2 immune mediated response are present in ears with chronic effusion. The increased levels of MPO in atopic patients further suggest that the general inflammatory response to putative inciting agents such as bacterial and viral products may be altered in atopy. These studies support the hypothesis that the exaggerated inflammation within the middle ear associated with most cases of OME is possibly the result of an atopic response within the middle ear itself.</p>

Otitis media with effusion (OME) is the major form of chronic relapsing inflammatory disease of the middle ear, constitutes the most common diagnosis for children under 15 years old and is the major cause of auditory dysfunction in pre-school children. OME is a disease more commonly found in allergic children. These studies sought to investigate the inflammatory response in the middle ear of patients and test the hypothesis that an allergic-like response might occur in the ear. Atopy was diagnosed by standard in vitro tests. Immunochemical techniques used to study classic allergic rhinitis and asthma were extrapolated to the evaluation of OME children whose effusion persisted beyond 2 months. Not only eosinophil cationic protein (ECP), tryptase, CD3-positive and IL-5 producing cells, but also myeloperoxidase (MPO) was found in middle ear fluid and/or mucosa in the majority of patients with OME and atopy. Initially, levels of ECP, MPO, and tryptase were measured in effusions from 97 random OME patients whose atopic status was determined by in vitro testing to 12 inhalants and 5 foods. The response of eosinophils, neutrophils and mast cells in the middle ear was distinctly different between atopic and non-atopic patients (p&lt;0.001) with higher levels of the cell markers in the atopic group of patients. This suggested that 1) perhaps OME was predominantly a disease of atopics and that 2) they differed in their response from non-atopics. Tryptase was measured in middle ear effusions from 38 patients with OME, 94.7% of whom were atopic by in vitro testing. Tryptase was elevated only in the effusion of atopic patients as compared to 5 controls (p&lt;0.01). Biopsies stained histochemically for tryptase showed evidence of mast cells in the mucosa and submucosa from 6 of 8 OME ears but absent in 4 normals. Middle ear biopsies, embedded in a plastic resin to improve the structural preservation, from 5 patients with OME and 5 normals were evaluated for the presence of eosinophils and neutrophils with monoclonal antibodies against 4 specific granule proteins. Eosinophils and neutrophils were present in the mucosa and mucus in significantly higher numbers than in the control group. In an effort to determine whether the middle ear itself might be involved in allergic disease, evidence that some of the cells, mediators and cytokines associated specifically with a Th-2 response were sought for in the middle ear mucosa of these children. Middle ear biopsies from 7 atopic patients with OME and 4 controls demonstrated the presence of activated eosinophils, CD-3+ T cells and IL-5 mRNA cells only in the mucosa from atopic OME children. Conclusion: Effusion and mucosal biopsies containing ECP, tryptase, and/or IL-5 mRNA cells, CD3+ T cells, eosinophils, and mast cells indicate that many of the mediators and cells essential to the production of a Th-2 immune mediated response are present in ears with chronic effusion. The increased levels of MPO in atopic patients further suggest that the general inflammatory response to putative inciting agents such as bacterial and viral products may be altered in atopy. These studies support the hypothesis that the exaggerated inflammation within the middle ear associated with most cases of OME is possibly the result of an atopic response within the middle ear itself.

Charles University Faculty of Pharmacy in Hradec Králové Study program: Pharmacy Candidate: Jana Roubalová Consultant: RNDr. Klára Konečná, Ph.D. Title of thesis: Optimization of methods for sensitivity evaluation of biofilm-forming microbial agents towards substances with antimicrobial potential Background: The aim of this diploma thesis was to optimize the methodical approach to the production of yeast biofilms in vitro on the so-called pegs and the walls of the wells of the 96-well panel. This biofilm formation system should be an analogous approach to the commercially available Calgary Biofilm Device. 10 strains of Candida yeast and 4 different culture media (nutritionally poor / rich) were used to optimize the methodology. Both the reference strains and the clinical isolates were among the yeast strains tested. Methods: The ability to form yeast biofilms by different strains in different culture media was evaluated by the approach of fixation, staining of the formed biofilms by crystal violet and extraction and spectrophotometric measurement of the intensity of the extracted color. Results: Individual strains, after cultivation in different media, were categorized according to their ability to form biofilm. Larger yeast adherence occurs in the wells than on pegs where the yeast adhered very...

In vitro dissolution, release and permeation testing is a common practice during drug product research and development. These in vitro tests, if predictive, are referred to as biorelevant tests and can play diverse roles to facilitate and expedite product development in a cost effective manner. Oral transmucosal products (OTPs) are currently tested using compendial and modified in vitro tests which may or may not be good predictors of in vivo performance due to a lack of biorelevance. A critical need for a broadly applicable and biorelevant in vitro system for OTPs has been expressed in the literature and the goal of this research was the development and validation of a biorelevant in vitro method that can facilitate accurate prediction of the in vivo behavior of OTPs. A combined strategy of appropriate apparatus design and relevant physiological and in vitro variable adjustment was investigated to incorporate biorelevance into evaluation of OTPs. A novel in vitro device, the bidirectional transmucosal apparatus (BTA), was designed and fabricated which allowed simulation of the oral cavity and its physiological variables to evaluate OTPs in a more realistic fashion. The BTA was tested using snus (a type of smokeless tobacco) as the OTP product. A simple and selective high performance liquid chromatographic (HPLC) method with photodiode array (PDA) detection was developed and validated to assess in vitro nicotine release and permeation (Linearity: 0.5 – 32 μg/mL; calibration curve accuracy (%recovery, n=5 ): 97.98-103.20%; calibration curve precision (%RSD, n=5): 0.15-3.14%). The performance of BTA was compared with the modified USP IV flow through apparatus (USP IV) and a commercially available vertical diffusion cell (VDC). The observed in vitro in vivo relationship (IVIVR) slopes with the USP IV, VDC and BTA were 0.27, 2.01 and 2.11 respectively. The BTA was selected over the VDC and USP IV devices because of better simulation and adjustment of variables to incorporate biorelevance in the test of OTPs. Additionally, the BTA allows study of permeation and release simultaneously unlike VDC and USP IV apparatuses. Further, the different BTA parameters were sequentially screened for their impact on in vitro rate of nicotine permeation that can be employed for the optimization of IVIVR for snus. Based on the results, stimulated saliva swallowing rate (SSSR) and media temperature were considered as significant factors affecting in vitro permeation of nicotine and used to further optimize IVIVR for snus. A 32 multifactorial experimental design integrating SSSR (0.32, 1.66 and 3 mL/min) and media temperature (25, 37 and 45 °C) was employed. Based on the response surface analysis, 0.55 mL/min SSSR and 43 °C media temperature were identified as optimal BTA conditions that would give perfect IVIVR (i.e. IVIVR slope close to one) for snus. The experimental value of IVIVR slope (0.92) at these optimal conditions indicated that the BTA is a valid in vitro system for evaluation of OTPs in a biorelevant manner. The applicability of BTA for predicting nicotine permeation from ‘Stonewall’, a dissolvable compressed tobacco was also evaluated. However, comparable in vitro nicotine permeation and in vivo nicotine absorption profiles were not obtained (ratio of in vitro permeation to in vivo absorption rate ranged from 0.04 to 0.14 at different in vitro conditions) either due to the unavailability of reliable clinical data or due to inherently different in vivo behavior of Stonewall compared to snus that would require further modification in the BTA. In conclusion, this research demonstrated the potential of the novel in vitro device to be a valuable tool for the prediction of in vivo performance of snus. The application of the novel bidirectional transmucosal apparatus for other types of OTPs will be an interesting subject for further investigation.

<p>Ventriculo-peritoneal shunting is the most commonly used method for the treatment of paediatric hydrocephalus. Despite improved shunts and surgical techniques there are still complications. This retrospective study focuses on diagnoses and treatment of shunt malfunction and infections. Cost/benefit of using an adjustable shunt was assessed. Two adjustable cerebrospinal fluid shunts and their compatible antisiphon devices were compared in-vitro.</p><p>In 21 of 46 children the standard shunt was changed to an adjustable one due to over-drainage. Adjustment of the shunt was performed in 73% of the children thereby avoiding surgery in several cases. This was a financial advantage.</p><p>Ascites or an abdominal pseudocyst without infection was detected in eight children due to resorption difficulties. A ventriculo-atrial shunt was inserted for a period of time. In three children it could successfully be reverted to a ventriculo-peritoneal.</p><p>In six children papilloedema was the only sign of shunt dysfunction. At revision the intracranial pressure ranged from 25 to 52 cm H₂O. Fundoscopic examination in children older than 8 years may detect symptomless shunt malfunction.</p><p>During a 13-year period 39 shunt infections were diagnosed. Skin bacteria were found in 80%. Prolonged and anaerobic cultures increased the detection rate by more than one third. The intraventricular infections were treated with intraventricular and systemic antibiotics resulting in quick sterilisation. No relapses were encountered. In five older children with distal catheter infection <i>Propionibacterium acne</i> was found. These were treated with intravenous antibiotics and exchanging of the shunt system.</p><p>Strata NSC^TM and Codman Hakim^TM worked according to the manufacturers except at the lowest setting. The resistance was below and in the lower range of the physiological one respectively. The antisiphon device of Strata shunt had to be placed in line with shunt to function properly. </p>