Abstract Background Pain is the ubiquitous human experience, yet displays considerable inter- and intraindividual variability in health and disease. Many factors have been proposed to account for these differences. Pain activates a complex stress response, multiply determined through genetic, psychological, physiological and neuroanatomical factors. Chronic pain is a central defining characteristic of functional gastrointestinal disorders. They represent a major challenge for modern health care. An integrated understanding of the pathophysiology of these disorders remains to be elucidated. Aims To investigate human psychophysiological responses to visceral and somatic pain in health and disease, in order to develop multidimensional and reproducible pain phenotypes. Methods Study I, in healthy volunteers, investigated personality traits, hypothalamic pituitary adrenal axes and selective novel non-invasive measures of autonomic tone in response to visceral and somatic pain. Study 2 examined the salience of genetic polymorphisms of the serotonin transporter. Study 3 evaluated the reproducibility of these responses after a period of one year. Study 4 utilised the methods of studies I and 2 in a case control study of patients with functional chest pain. Key Results Studies I, 2 and 3 - Two pain phenotypes, or clusters, were found - cluster I (39%) had higher neuroticism scores, with higher sympathetic and hypothalamic pituitary adrenal axis tone at rest, and a predominant parasympathetic response to pain in the presence of the short allele of the serotonin transporter. Cluster 2 (61 %) displayed the converse profile in the absence of the short allele. These responses were stable at an interval of one year. Study 4 - similar phenotypes were observed in patients with functional chest pain, although the Cluster I phenotype was overrepresented in patients in comparison to the controls (71 % vs. 29%). Conclusions and Inferences This series of studies provides evidence for the existence of two reproducible human pain phenotypes in health, which have clinical salience in patients with functional chest pain. By phenotyping pain responses, subject homogeneity in future studies may be improved. Furthermore, such phenotyping techniques may open new therapeutic avenues by facilitating the selective targeting of nociceptive aberrancies, particularly in functional gastrointestinal disorders.

Meningococcal meningitis from the causative organism Neisseria meningitidis is the leading cause of meningitis globally. This bacterium is among a limited number of pathogens that have the propensity to cross the blood brain barrier (BBB) vasculature causing meningitis. It has been recently demonstrated that Neisseria meningitidis targets the laminin receptor (37 LRP/67 LR) on the surface of human brain microvascular endothelial cells, and two meningococcal outer membrane proteins, PorA and PilQ, have been identified as bacterial ligands. Interestingly, this interaction is hypothesized to underlie meningococcal tropism for the central nervous system (CNS). There are two isoforms of laminin receptor; monomeric 37 kDa laminin receptor precursor (37 LRP) and mature 67 kDa laminin receptor (67 LR). The relationship between the 67 LR and its precursor 37 LRP is not completely understood, but previous observations have suggested that 37 LRP can undergo homo- and/or hetero- dimerization with Galectin-3 (Gal-3) to form mature 67 LR. Gal-3 is the only member of the chimera-type group of galectins, and has one C-terminal carbohydrate recognition domain (CRD) that is responsible for binding the ß-galactoside moieties of mono- or oligosaccharides on several host and bacterial molecules, including neisserial lipooligosaccharide (LOS). To identify the LOS-independent meningococcal ligands that bind Gal-3, binding of lactose liganded Gal-3 and CRD with meningococci was investigated using ELISA assay. Neisseria meningitidis bound lactose liganded Gal-3 significantly more than H. pylori, which is known to bind Gal-3 via LPS. This binding was not inhibited by increasing concentrations of lactose. Also the lactose liganded CRDof Gal-3 bound meningococci but to a lesser extent than full molecule. Importantly, binding of Gal-3 was conserved among 25 meningococcal clinical isolates tested in the current study. A meningococcal mutant lacking the glycosyltransferase required for chain elongation from the core lipid A-(KDO)2-Hep2 showed reduced binding to lactose-liganded Gal-3, but binding was not abolished indicating that the meningococcal-Gal-3 binding was not entirely LOS-dependant. Using a re-tagging approach, meningococcal PilQ and PilE proteins were identified as Gal-3 binding ligands. Mutation of the genes encoding either of these two molecules in strain MC58 led to a significant reduction in Gal-3 binding. PilQ is not known to be glycosylated, therefore its interaction with Gal-3 is likely to be protein-mediated. PilE is post-translationally glycosylated and deletion of the pilin glycosylation genes pglC and/or pglL dramatically reduced bacterial-Gal-3 binding. Given the binding of meningococcal PilQ to 37 LRP/67 LR and Gal-3, this study sought to investigate possible dimerization between 37 LRP and Gal-3 to form 67 LR. Double immunofluorescence staining of endogenous receptors revealed colocalization of 67 LR with its precursor and both of them with Gal-3 in HBMECs, astrocyte and COS7 cells. Moreover, co-expression of 37 LRP and Gal-3 fused to different fluorescent proteins indicated colocalization of these receptors in COS7 cells. Using bimolecular fluorescence complementation (BiFC) assays, the presence of 67 LR in homo- and hetero-dimer forms with Gal-3 has been confirmed in different cell lines. In addition, the recombinant laminin receptor bound Gal-3 and its CRD to comparable level. Further investigation for Gal-3 and 37 LRP dimerization mechanism revealed that the conserved cysteine (C173A) within the CRD of human Gal-3, which is known to abolish disulphide-mediated dimerization of murine Gal-3, is critical for Gal-3 homo- and hetero-dimerization with 37 LRP, whereas neither of the two cysteines on 37LR (cys148 and cys163) are required for dimerization. To examine the role of Gal-3 in meningococcal interaction with host cells, the adhesive and invasive capacities of meningococci were compared between Gal-3 transfected and non-transfected neuroblastoma cell line (N2a) cells. Transient expression of Gal-3 in mouse N2a cells significantly enhanced meningococcal invasion when compared with non-transfected cells. Moreover, infection of CD46-expressing transgenic mice with meningococcal strain MC58 significantly increased the expression of Gal-3 and 37 LRP in the brain. This work also attempts to study whether the 37 LRP/67 LR meningococcal ligands (rPorA, loop 4 of PorA and rPilQ) have any influence on the surface level of 67 LR and Gal-3. As indicated by flow cytometry analysis, recruitments of 67 LR and Gal-3 to the surface of HBMECs were increased in cells incubated with rPilQ, Loop 4 of PorA and more prominently rPorA. To examine these results in more detail, effect of each of these ligands on 37 LRP expression was investigated using qPCR. Loop4 of PorA and rPilQ induced 37 LRP expression significantly more than PBS. Although there was a trend for an increase in 37 LRP expression with treatment with rPorA, the difference was not statistically significant (p = 0.1507). Further investigation in future study for the effect of these bacterial adhesins on Gal-3 gene expression will be of great value. Collectively, these data revealed the capacity of Gal-3 to target meningococcal PilQ and PilE, as well as the previously known LOS and showed the importance of Gal-3 in the meningococcal-host cell interaction. This interaction may be part of host-cell defence against the organism, and/or, conversely, it may be part of a strategy adopted by the organism to modulate the host response and facilitate its invasion. Remarkably, the current findings also demonstrated the existence of 67 LR as homo- and hetero- dimer with Gal-3. This dimerization of two meningococcal host receptors may help to extend spectrum of their bacterial adhesins which may act cooperatively or synergistically at different stages of infection. Besides, the expression pattern of these receptors may suggest specific receptor repertoire in the BBB which might contribute in meningococcal tropism for the CNS.

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The Anthony Nolan Register provides donors for allogeneic stem cell transplantation for haematological disorders. A clinical database and sample bank were established for the ongoing analysis of transplants from Register donors. Clinical data and blood samples were collected from donors and patients transplanted in the UK from 1996 onwards. DNA was extracted from all samples received, and used for the detection of HLA mismatches at six loci (HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1) by RSCA, and HA-1 by SSP. 138 donor/patient pairs were selected for a pilot study. HLA matching between patient and donor, along with the diagnosis of the patient, donor and patient age, CMV status and gender, and the T cell depletion status of the transplant were analysed for their effect on transplant outcome. The outcome variables studied included overall survival, disease free survival, transplant related mortality, relapse incidence, and the occurrence of acute and chronic GvHD. Patients with AML had decreased overall and disease free survival, and patients with CML had increased risk of relapse. Transplant from a same sex donor increased the risk of death or relapse, and male patients receiving stem cells from female donors showed reduced overall survival. Developing acute GvHD increased the risk of transplant related mortality. A mismatch at HLA class I and at class II was associated with unfavourable outcome for all survival variables. The inclusion of HLA-DPB1 matching did not alter the effects seen when other mismatches were present. Matching at the allele level for all loci gave an increased risk of relapse compared with patients mismatched with their donor for HLA-DPB1 only, indicating that a mismatch for HLA-DPB1 alone may protect from relapse. The data from this study was used to calculate the numbers required for a definitive study, for the optimisation of donor selection from the Register.

The present thesis is concerned with the character of kinds in human somatic pathology and the relation that these kinds and their members have with function-based explanations. More precisely, in the first part of the thesis I investigate whether diseased organisms, grouped together on grounds of their shared pathological features, could form natural kinds, taking into account that the paradigmatic natural kinds are the kinds of the exact sciences. The second part of the thesis has as a backdrop the Humean/anti-Humean debate over causation (and the specific construal of explanations according to which to explain is to pinpoint causes). In this backdrop, I enquire into what sort of function-based explanations we could provide for the symptoms and pathological behaviours exhibited by diseased organisms, if we construe such organisms as members of natural kinds. I argue in the first part of the thesis that from a metaphysical point of view, the organisms dealt with in somatic medicine form natural kinds in the same sense in which we take the kinds dealt with in the exact sciences as natural. By comparing a 'classical', exact science kind with a kind of disease, I show that whatever features are associated with natural kind membership (e.g, involvement in laws or inductions, explanatory relevance, possession of 'essential' properties, instantiation of substantive universals, etc.) there is no 'ontological gap' between disease kinds and the kinds in the exact sciences. The conclusion that diseases are natural kinds has a certain proviso regarding the question of whether the identity of the individual members of natural kinds is dependent upon their kind membership. Should diseases not be natural kinds, the proviso says, it would be because the properties characteristic of natural kinds must have an identity-influence over the kind members. I present in addition serious problems posed by outlining such identity bearing properties. In the second part of the thesis, I argue that function based explanations concerned with diseased organisms - if we construe such organisms as being members of natural kinds - should illuminate positive causes for the symptoms and pathological behaviours they exhibit. We could obtain such function-based explanations, I suggest, if we interpret the functioning of biological items as the manifesting of causal powers. Against the background of the Humean vs. anti-Humean debate on causation, I show that Nancy Cartwright's capacities are a plausible variant for the powers at work in 'pathological' functioning. I argue that one could track down these capacities if one viewed healthy organisms as nomological machines, in the sense in which Cartwright understands this notion. I also suggest that capacities are necessary in order to vindicate general and, more importantly, singular causal claims involved in medical diagnosis and hence to found satisfactory functional explanations.

I was responsible for developing the Human Gene Mutation Database (HGMD), which represents a comprehensive core collection of data on germ-line mutations in nuclear genes underlying or associated with human inherited disease (http://www.hgmd.org). This was essential to provide a high quality resource for the meta-analysis of human mutation data. HGMD currently contains 8181 (17%) micro- deletions (<20 bp) and 3268 (7%) micro-insertions (< 20 bp) in 918 and 652 genes respectively. A positive correlation was found between the frequencies of micro- deletions and micro-insertions for the 564 genes for which both micro-deletions and micro-insertions were reported suggesting that the likelihood of a micro-deletion and a micro-insertion co-occurring in a given gene are related. When the micro-deletion study was initiated, the data-set contained 3767 micro-deletions from 426 genes, whilst the micro-insertion study utilized a data-set of 1960 micro-insertions from 307 genes. Micro-deletions and micro-insertions of 1 bp constituted 48% and 66% of the respective totals and a negative correlation was found with the number of base-pairs deleted or inserted. However, the frequencies of micro-deletions and micro-insertions of 3 bp and 6 bp were significantly lower than predicted, suggesting that a proportion of these do not come to clinical attention. Many of the micro-deletions and micro- insertions were explicable by slipped mispairing, particularly micro-insertions, with 89% being explicable by DNA sequence duplication. Several sequence motifs were found to be over-represented in the vicinity of both micro-deletions and micro-insertions, including the CCCCCTG motif which shares homology with part of the prokaryotic Chi recombination hotspot (GCWGGWGG). A previously reported indel hotspot motif GTAAGT and its complement ACTTAC were found to be over-represented in the vicinity of both micro-deletions and micro-insertions, representing the first example of a mutational hotspot common to different types of lesion. Other motifs that were over-represented in the vicinity of both types of lesion included DNA polymerase pause sites and topoisomerase cleavage sites. Thus, micro-deletions and micro-insertions exhibit strong similarities in terms of the characteristics of their flanking DNA sequences, implying that they are generated by very similar underlying mechanisms.

Cutaneous delivery of macromolecules is significantly impeded by the inherent barrier properties of the stratum corneum (SC). Within the last decade sophisticated engineering techniques have enabled the manufacture of microneedle arrays. These are innovative devices consisting of micron-sized needles which when inserted into the skin create physical conduits across the SC but do not impinge upon underlying nerve fibres or blood vessels. This study assessed the ability of microfabricated silicon microneedle arrays to penetrate the SC of ex vivo human skin for the localised delivery and subsequent expression of non-viral gene therapy formulations. Cutaneous gene therapy may represent a new method for the treatment of, or vaccination against, a range of candidate diseases. Microneedle arrays of variant geometries and morphologies, created using dry- and wet-etch microfabrication methods, were characterised by scanning electron microscopy. The potential of these devices for the cutaneous delivery of gene therapy formulations was initially demonstrated by permeation of a size and surface representative fluorescent nanoparticle across microneedle treated human epidermal membrane and observation of these nanoparticles in micron-sized conduits created in excised human skin. The ability to express exogenous genes within ex vivo human skin was subsequently proven by intradermal injection of the pCMVp reporter plasmid. However, a non-viral gene therapy vector failed to enhance cutaneous transfection. Cutaneous plasmid DNA delivery using the microneedle device facilitated effective, if somewhat limited and irreproducible, transfection of epidermal cells proximal to microchannels created in the skin. These investigations confirmed the ability of a silicon microneedle device to deliver macromolecular formulations, including plasmid DNA, to the viable epidermis and have demonstrated exogenous gene expression within human skin. However, limited and unpredictable gene expression following microneedle mediated delivery indicate that further studies to optimise the microneedle array morphology, its method of application and the plasmid DNA formulation are warranted.