Call number: LD2668 .T4 1949 G61 / Master of Science

Call number: LD2668 .T4 1961 D43

Call number: LD2668 .T4 1962 T73

The specificity of guinea pig liver transglutamlnase was Investigated by the determination of modification sites within polypeptides and proteins of known sequence and (In some cases) folded structure. It was shown that some globular proteins have substrate properties for transglutamlnase In conformations which resemble their native states. Novel substrate sites for transglutamlnase were determined within the following proteins: 1) bovine B-Iactoglobulln. 2) the Hls3~ Gln388 mutant form of yeast phosphoglycerate kinase. 3) bovine B-caseln. 4) porcine pepsin. Despite the high exposure of many glutamlnyl residues within these proteins only a small fraction of these residues were observed to be reactive towards transglutamlnase. This Is taken to Indicate that features such as the chemical nature of the amino acid side chains In the local vicinity of unreactive glutamlnyl residues strongly determine the specificity of transglutamlnase. When structural models were available for substrates of transglutamlnase, the local secondary structure associated with substrate sites could be assessed. When no such models were available computer based methods were used to predict the local secondary structures associated with these sites. This approach allows substrate sites to be classified according to their local conformational preference Into conformationally flexl ble (type A substrates) and more conformationally restricted (type B substrates). Since diverse amino acid sequences are observed to surround the reactive glutamlnyl residues of many of the non-physiological substrates of transglutamlnase, It was assumed that the glutamlnyl residues within these sequences were probably reactive due to having; 1) a favourable stereochemistry during modification by transglutaminase 2) a lack of Inhibitory features. In order to determine why some exposed glutamlnyl residues were reactive and others not, It was necessary to find features which were present In unreactive sequences but absent In reactive ones. Through the use of this approach an "anti-consensus sequence" motif was Identified. This was based on the observation that exposed glutamlnyl residues which were unreactive towards transglutamlnase often have charged residues within their surrounding sequences. The distribution of allowed/disallowed residues within substrate sequences, together with what Is known concerning the conformational preference of transglutamlnase for its substrates was built Into a preliminary set of "rules'·. These rules may provide a basis for understanding the observed specificity of transglutamlnase. The application of these rules to a number of model systems has resulted In the correct prediction of both reactive and unreactive glutamlnyl side chains within a number of proteins. The demonstration of the substrate properties of the Hls3~ln388 mutant of phosphoglycerate kinase Illustrates the feasibility of Introducing a novel substrate site for transglutamlnase Into a protein using recombinant DNA technology.

This study is concerned with a critical comparison of the passive transfer mechanisms of tuberculin and chemical contact hypersensitivities in the guinea pig by use of a four phase experimental approach.

Call number: LD2668 .T4 1950 W3 / Master of Science

No description available.

Contact Lens Acute Red Eye (CLARE) and Infiltrative Keratitis (IK) are inflammatory responses of the eye associated with extended wear of soft contact lenses. Bacterial colonization of contact lenses with Gram-negative bacteria such as Pseudomonas aeruginosa is an important risk factor for the development of these adverse responses. Strategies that control the bacterial colonization of contact lenses may help prevent the occurrence of adverse responses. This thesis aimed to develop an animal model of CLARE/IK to test this hypothesis and to test the effectiveness of contact lenses containing antimicrobial compounds, namely silver and furanone compounds, in controlling corneal inflammation caused by Pseudomonas aeruginosa. A guinea pig model of contact lens wear was developed for the study and it was observed that the ocular responses to contact lens wear in the guinea pig were similar to those seen in human eyes wearing contact lenses. Also, three different models for CLARE/IK were developed and tested in the guinea pig eye. The pathological features of CLARE/IK in the guinea pig were virtually identical to those observed in human eyes. Bacterial contamination of contact lenses was confirmed to be a major risk factor for the development of CLARE/IK. Contact lenses containing nano-particles of silver demonstrated very good antibacterial activity against Pseudomonas aeruginosa in-vitro. The silver lenses were able to control the development of CLARE/IK responses in one of the models for CLARE/IK. Silver lenses might be most effective if used to prevent the establishment of a biofilm of bacteria on a lens such as might occur during storage in a contact lens case. Contact lenses were coated with different concentrations of the furanone compounds by physical adsorption and demonstrated good antibacterial activity at higher concentrations. However these concentrations were cytotoxic in-vitro and lower concentrations of furanones did not possess adequate antibacterial activity to control CLARE/IK responses in-vivo. This thesis has successfully demonstrated that guinea pigs can be used to test the effects of extended wear of contact lenses and developed models to test the pathogenesis of adverse responses such as CLARE/IK. The CLARE/IK models developed could be used to further our understanding of the pathogenesis of these inflammatory conditions and explore the activity of other antimicrobials.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 72-104).

Thesis (M. Phil.)--University of Hong Kong, 1980. / Typescript.