No description available.

No description available.

No description available.

<i>PAX77⁺</i> mice were shown to express about 150% of wild-type Pax6 levels of corneal epithelial Pax6 and displayed abnormally small corneas due to a failure of postnatal growth and development of the cornea.  The proliferative component of the corneal epithelium was normal, cell cycle progression appears unaffected and there are no abnormal apoptotic events.  Cytokeratin-12 expression was down regulated in the <i>PAX77⁺</i>corneal epithelia, implying differentiation is incomplete, and the corneas of <i>PAX77⁺</i> were found to display increased fragility in comparison to wild-types. <i>PAX77⁺</i> corneas displayed sever wound healing abnormalities which in contrast to Pax6^+/-can not be rescued by EGF addition.  Both <i>Pax6^+/-</i> and <i>PAX77⁺ </i>corneal epithelia show no improvement in wound healing with addition of Shh peptide or all-trans retinoic acid (in contrast to wild-type), however in the <i>PAX77⁺ </i>wound healing abnormalities do not lead to corneal opacity which is seen in <i>Pax6^+/-</i>.  Both <i>Pax6^+/-</i> and <i>PAX77⁺</i>corneal epithelia have increased basal levels of retinoic acid signalling in their corneal epithelium when compared to wild-type littermates.  Topical application of Shh increased RA signalling in the corneal epithelium. As described above a severe reduction in corneal size was observed in the <i>PAX77⁺</i> mouse: defective lens signalling as a result of Pax6 dosage was postulated to lead to this.  The lens is highly sensitive to Pax6 dosage.  Mouse/chick secondary chimeras were produced, through the grafting of <i>PAX77⁺</i> and wild-type mouse lenses into a chicken eye, to investigate the role of altered Pax6 dosage in the lens on anterior eye development.  <i>PAX77⁺</i> mouse/chick secondary chimeras, remarkably recapitulated the anterior eye phenotype seen in <i>PAX77⁺</i> mice. This supports the role of altered Pax6 dosage in the lens resulting in the corneal abnormalities of the <i>PAX77⁺</i> model.

Wound treatment remains one of the most prevalent and economically burdensome healthcare concerns, often complicated by prolonged inflammation and bacterial infection, contributing to morbidity and mortality. Agents commonly used to treat chronic wound infections are limited due to their toxicity, multifactorial etiology of chronic wounds, deep skin infections, lack of sustained controlled delivery of drugs, and development of drug resistance. LL37 is an endogenous host defense peptide that has been shown to exhibit antimicrobial activity and is involved in the modulation of wound healing. Serpin A1 (A1) is a neutrophil elastase inhibitor and has been shown to demonstrate wound-healing property. Hence, our goal was to develop a topical combination nanomedicine for the controlled sustained delivery of LL37 and A1 that at precise combination ratios will significantly promote wound closure, reduce bacterial contamination, and enhance anti-inflammatory activity. We have successfully developed a solid lipid nanoparticle (SLN) formulation that can simultaneously deliver LL37 and A1 at specific ratios resulting in accelerated wound healing by promoting wound closure in BJ fibroblast cells and keratinocytes as well as synergistic enhancement of antibacterial activity against S. aureus and E. coli in comparison to LL37 or A1 alone. / May 2016

Thesis (M.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-01

Within the five experimental chapters of this doctoral thesis (i) the eubacterial diversity of the microbiota of chronic wounds and healthy skin was investigated, (ii) biofilm formation and associated coaggregation interactions of wound and skin-associated bacterial isolates was examined, (iii) formulation of media which reproduced some aspects of the nutritional conditions of wounds and healthy skin were developed, (iv) novel wound biofilm models were developed and validated and (v) microbial population interactions associated with healthy skin and chronic wounds were investigated using a novel model system. (i) The microbial diversity of chronic wounds and contralateral skin swabs was investigated using culture, denaturing gradient gel electrophoresis (DGGE) and microscopy. Intrapersonal analysis identified that non-infected wounds had a proportionally higher incidence of bacteria which were identified on contralateral healthy skin according to DGGE analysis when compared to infected wounds indicating that taxonomically distinct consortia are associated with infection. Microcolonies and putative biofilms structures were identified in both culture-defined infected and non-infected wounds indicating that the presence of biofilms may not be linked to infection. (ii) By assessing pair-wise combinations of skin and wound-associated bacteria, the role of coaggregation in the formation of wound polymicrobial communities was assessed using a quantitative spectrophotometric assay. Aggregation interactions were weak or not detectable, apart from those associated with Corynebacterium xerosis. This bacterium produced a high autoaggregation score (c. 50%). The limited coaggregation interactions suggest that coaggregation may be comparatively unimportant in the development of wound biofilms. (iii) In order to facilitate the development of biofilm models specific to chronic wounds, the formulation of representative growth media is important in order to reproduce the in situ nutrient environment. Therefore complex, artificial sweat and serum media broadly reflective of the nutrient availability in wounds and healthy skin were developed and validated based upon their ability to support realistic phenotypes (assessed by proteomics) and the growth of a range bacterial isolates. Developed media maintained the sessile growth the test bacteria and produced broadly similar proteomic profiles to foetal calf serum. (iv) Two novel model systems were developed to study cross-sectional population interactions and to investigate longitudinal population development of wound consortia and biofilm formation. A fine celled foam (FCF) multi-well wound model and a multiple membrane FCF model maintained dynamic steady state of axenic and mixed populations of bacteria associated with chronic wounds and supported the development of biofilms. (v) The FCF multi-well wound model was used to investigate population interactions in environments broadly reflective of healthy skin and wounds. When grown in artificial sweat prior colonisation with Staphylococcus saprophyticus resulted in a significant reductions in methicillin resistant Staphylococcus aureus (99%) and P. aeruginosa (75%) whilst prior colonisation by C. xerosis resulted in a significant reduction in P. aeruginosa (91%) only. However no significant reductions in pathogenic bacteria were noted in artificial serum indicating colonisation resistance could be simulated in the model and the outcome of immigration was markedly influenced by the species of established bacterium and nutrient availability.

Activities aimed at treating and/or monitoring the healing of wounds consume many nursing hours. However, most of the treatments used by nurses in caring for wounds are best classified as "reports of techniques" and are not based on research. Though no single initiator or promoter of wound healing has been isolated, epidermal growth factor (EGF), a naturally occurring polypeptide, has been reported to promote epidermal growth in vitro. In vivo, the application of EGF has been reported to increase proliferation and differentiation of epidermal tissue in newborn mice and to enhance the healing of corneal wounds in rabbits. Originally found in the submaxillary gland of male mice, EGF has now been found in the urine of humans. No reports have documented the in vivo effects of application of EGF to epidermal wounds of animals to determine if it will promote wound healing. The purposes of this study were to further elucidate the physiological and perhaps therapeutic function of EGF and to evaluate the feasibility in terms of availability, cost, and manageability of the pig as an animal model for controlled investigation of clinical nursing problems. Wound healing is a composite phenomenon of distinct yet interrelated phases: epithelialization, contraction, and fibrous healing. The reepithelialization of the wound is the result of migration of epidermal cells adjacent to the wound edge and differentiation of the new cells. Because of the risks and ethics involved in repeated biopsy of human wounds and the prematurity of use of EGF in humans, the specific problem this study was designed to answer is: Does the topical application of mouse epidermal growth factor (mEGF) increase the rate of healing of epidermal wounds in the domestic pig? An experimental design was used to test four hypotheses. Three of the hypotheses related to the process of wound healing were: (1) Topical application of 40 ng of mEGF will increase migration of keratinocytes over the wound. (2) Topical application of 40 ng of mEGF will increase the mitotic index. (3) Topical application of 40 ng of mEGF will increase the differentiation of keratinocytes over the wound. A fourth hypothesis, topical application of 40 ng of mEGF will increase the protein/DNA ratio in keratinocytes adjacent to and covering the wound, was tested since EGF is reported to be a potent mitogen increasing DNA synthesis and increasing intracellular protein. Using a modification of the Winter method, 82 wounds were created on the backs of ten young Yorkshire mix pigs in order to simulate the healing of two wounds over time. Mouse EGF was applied every two hours for six hours then every six hours for 48 hours (total of 54 hours) and 0.9 percent sodium chloride was applied to the control wounds in identical fashion. Tissue obtained from randomly assigned timed biopsises were examined histologically for the migration, mitosis, and differentiation of the keratinocytes. In addition, a portion of each biopsy was utilized for determination of protein/DNA ratio. Dependent t-tests of means showed no statistically significant differences between mEGF treated experimental and control wounds. Therefore, none of the hypotheses were supported. Graphic presentation of the data does indicate differences at specific points especially in the first 18-48 hours post-wounding. The pig was found to be a satisfactory model for controlled studies since the epidermal tissue is similar and the animals are relatively inexpensive, readily available, and become domesticated or relatively easy to handle in a short period of time.

This research project focused on a range of polysaccharides, including sodium alginates (with varying mannuronic (M)/guluronic (G) acid ratio), pectin and sodium carboxymethylcellulose (CMC), for wound dressing applications. The samples were prepared as mixed salts such as sodium/calcium salts as Ca2+ ions are known to promote faster healing. The aims of this research were: 1- to provide a greater insight into the nature of binding between various ions (NaT, Ca2+ as well as Zn2+ and Ag+) and the polysaccharide molecules. Interactions between alginate/pectin and alginate/CMC molecules were also studied. This was achieved using a range of analytical techniques such as Fourier transform infrared spectroscopy, Raman spectroscopy and neutron spectroscopy, thermogravimetric analysis, microprobe analysis, X-ray diffraction and atomic absorption spectroscopy. It was found that sodium ions were bound to the carboxyl groups of the alginate molecules, whilst calcium ions attached themselves onto COO- as well as onto the alginate backbone, leading to crosslinked structures. Appearance of OH ... -OOC to the detriment of OH ... OH bonding was also observed. Addition of zinc ions involved greater constraint in the alginate network and the silver ions were believed to produce insoluble alginate salts, due to their larger ionic radius; furthermore hydroxyl-hydroxyl interactions in the silver alginate were rather between the polymer molecules than with the water. The addition of pectin to alginate led to partial binding between the two polysaccharides via hydrogen bonds. By contrast, carboxymethylcellulose molecules were found to act as independent entities in contact with alginate, and therefore suggested incompatibility. 2- to determine the performance of sodium/calcium alginate systems as well as Na/Ca alginate/pectin and Na/Ca alginate/CMC systems, in order to improve properties such as absorbency, gel strength and calcium release (to assess the haemocompatibility) in a simulated serum solution. A greater calcium and guluronic acid content was found to improve the gel strength of alginate samples, but decrease the swelling ability. Calcium release was favoured with a low G and a high calcium content. Addition of a second polysaccharide enhanced these gel properties. For example, the gel strength could be significantly increased with a 25 % pectin addition, while addition of CMC up to 50 % increased both the swelling and the calcium release. 3- to develop a new model of the ion release process for a polysaccharide system brought into contact with a simulated serum solution. It was based on a "hoppingtrapping" mechanism for the calcium ions, whereby different release rates are due to different affinities with the polysaccharide blocks.

No description available.