Human skin colour has significant aesthetic and cultural implications. Cutaneous injuries can result in dys-pigmented scars which are more noticeable, aesthetically unpleasant, and can lead to patient distress and social isolation. Management of dys-pigmented scars has been challenging with variable success. There is a limited understanding of the timing, progression and mechanisms of skin re-pigmentation following wounding. This thesis is a detailed sequential study, which describes and quantifies scar colour changes in pigs of different pigmented strains.The first result chapter describes the observational pigmentary changes in scars of four different pigmented pig strains (Hampshire, Yucatan, Tamworth and Duroc) over time. Two scar re-pigmentation progression patterns, specific to the darkly and the lightly pigmented pigs, are identified and all scar photographs of all pigs at all time-points are scored during non-invasive wound/ scar monitoring using a semi-quantitative scale. In the second result chapter, histo-chemical (DOPA-oxidase) staining was combined with immuno-histochemistry (HMB45) to establish the spatial and temporal distribution and activities of melanocytes in the regenerated epithelium of darkly pigmented pig strains. Results suggest a rise in both inactive and active melanocyte numbers in re-pigmenting scars at early time-points and by late time-points, scars achieved ‘complete re-pigmentation’ and melanocyte numbers were lowest. Late melanocyte proliferation was observed in two scars from two different pigs; one of which manifested this as hyper-pigmentation, macroscopically. In addition, histological analysis of the epidermal melanin staining (Warkel-Luna-Helwig) pattern showed good correlation with the macroscopic appearance of the scars. The effect of changes in scar basement membrane undulation on melanocyte packing density was investigated: changes were small and unlikely to impact melanocyte packing density; hence macroscopic scar colour. Macroscopic and microscopic observations of the pattern of re-pigmentation following creation of partial thickness wounds across the white and black belts of three Hampshire pigs were investigated.The final result chapter describes how colour changes were quantified for scars and normal skin of each pig, at all time-points during non-invasive scar monitoring; using a reflectance spectrophotometer. In addition, the sensitivity of objective colour measurements was investigated. Results using two statistical clustering techniques suggest that colour measurements differentiate scars from the surrounding normal skin and the tristimulus L*a*b* values of scars correlate well with their macroscopic colour appearances. Time-dependent colour changes in scars and normal skin were quantified independently, using polynomial analysis. The results suggest systematic colour changes in most scars of all pig groups, except Yucatans’, which on the other hand, showed systematic colour changes to their normal skin. These findings highlight the importance of independent analysis of scar and normal skin colour measurements with time post wounding. In conclusion, this thesis has investigated timing and progression patterns of scar re-pigmentation in pigs of different pigmented strains.

Through multiple complex mechanisms, the endocrine system plays a vital regulatory role in virtually every organ system including the skin. Cutaneous lesions may be seen incidentally in patients with endocrine disorders. Alternatively, certain skin conditions are seen exclusively in the setting of endocrine disorders and may rarely be the first clinical symptom of the underlying endocrinopathy. Although clinical examination is often sufficient, a tissue biopsy may still be needed to arrive at or confirm the diagnosis and to direct therapy. In many cases, the cutaneous condition might improve or resolve completely after treatment of the underlying endocrine disorder. In this review, we summarize the most common skin conditions associated with endocrine disorders, uncovering their relationship to the underlying endocrinopathy, demonstrating their clinicopathologic presentation, and highlighting their typical modalities of treatment.

Through humoral and cell-mediated mechanisms, the immune system plays a vital role in protecting every organ system. Disorders of the immune system may result in various cutaneous manifestations, including cutaneous malignancies. In patients with immunodeficiency, the risk of development of malignant cutaneous neoplasms is substantially increased. This increased risk may be due to oncogenic viruses that find a suitable microenvironment for tumorigenesis and cancer development. A subset of cutaneous malignancies that develop in patients with immunodeficiency may show aggressive clinical and biological behavior. Here, we report six cases of highly aggressive and deadly cutaneous neoplasms that arose in patients with a known history of immunodeficiency: two cases of Kaposi sarcoma in patients with immunosuppression due to human immunodeficiency virus infection; a case of Merkel cell carcinoma and a case of squamous cell carcinoma (SCC) in patients receiving immunosuppressive drugs after organ transplant; a case of multiple cutaneous tumors, including invasive melanoma, SCC, and sebaceous carcinoma, in a patient with hypogammaglobulinemia and a history of organ transplant; and a case of basal cell carcinoma and melanoma in situ in a patient with primary immunodeficiency.

No description available.

The dermal papillae of the hair follicle control its growth, differentiation and apoptosis via a range of growth factors. These secreted growth factors are known to differ between those of non-balding scalp and those of balding scalp and can even differ in response to a common stimuli – androgen. In balding scalp androgen stimulates the secretion of negative growth factors, while in non-balding scalp androgen is found to exert little or no effect. Dermal papilla cells (DPCs) can be cultured in vitro, however those from balding scalp have been found to undergo premature senescence compared to those from non-balding scalp. A major cause of premature senescence is oxidative stress – the gradual accumulation of reactive oxygen species within the cell causing deleterious loss of function. Reactive oxygen species are known to be mediated in response to androgens and growth factors and in turn may affect growth factor signalling within the cell. Using low oxygen cell culture as a means of reducing oxidative stress, balding and non-balding DPCs were grown and characterised. It was confirmed that low oxygen culture could increase proliferation, delay senescence and reduce reactive oxygen species with both DPC types and that balding DPCs showed a higher sensitivity to oxidative stress. It was also found that secretions of growth factors by the balding DPCs in response to different oxygen conditions differed greatly to that of the occipital DPCs. Androgen, but not TGF-β was found to modulate DPC production of catalase, an antioxidant, under low oxygen conditions and this caused a reduction in reactive oxygen species in the balding DPCs. Balding DPCs also demonstrated an upregulation of the antioxidant total glutathione, however had a reduced fraction of the active reduced form of the molecule. In addition, it was shown for the first time 3 that under cell culture conditions balding DPCs express TGF-β receptors and it was shown that proliferation and migration of the balding DPCs could be affected by addition of exogenous TGF-β, highlighting a potential role for TGF-β as an autocrine growth factor in the balding dermal papilla.

CD44 has been described as a marker of cancer stem cells in oral squamous cell carcinoma (OSCC). The main objective of this study was to characterise expression of CD44 in both fresh samples of human OSCC and in cell lines generated from them, and to examine its correlation with selected clinicopathological parameters of the tumours of origin. The epithelial fraction in 20 fresh OSCC samples was identified by the standard method using the negative selection technique with antibodies against non-tumour cells. A novel method of identifying the epithelial fraction, termed positive selection, was also developed and used for analysis of 14 additional OSCC samples. This new method, using epithelial-specific antibodies, led to a considerable improvement in the efficiency and the accuracy of the procedure. The frequency of CD44+ cells in the epithelial fraction of the tumour specimens was assessed by FACS and varied widely (3-97%). High frequency of CD44+ cells in tumour samples was found to be associated with high tumour grade, discohesive invasion front and presence of lymph node metastases (p<0.01, as calculated with Spearman’s ranked test and Fisher’s exact test). It was also observed, that the percentage of CD44+ cells changes when cells isolated from tumour samples are propagated in culture. Nearly all cells in cell lines generated from OSCC samples showed CD44 expression when analysed by FACS. However, a markedly higher level of CD44 expression (as assessed by median fluorescence intensity for cell surface CD44) was found for early passage cell lines generated from metastatic OSCC and lymph node metastases as compared to cell lines generated from nonmetastatic OSCC. These findings show that a high frequency of CD44+ cells in fresh OSCC tissue and a high level of CD44 expression in cultured OSCC cells correlate 11 with more aggressive tumour behaviour. These results might provide important information of prognostic and therapeutic value.

The Aim of the project was to investigate cell senescence in basal cell carcinoma (BCC). Although the concept of oncogene-induced senescence (OIS) was originally confined to cultured cells, it is now well established that this mechanism has an important role in tumour biology. OIS represents a physiological response that restricts the progression of benign tumours into their malignant counterparts e.g. nevi to melanoma or adenoma to adenocarcinoma. Full malignancy is associated with the loss of important tumour suppressor genes including RETINOBLASTOMA and/or TP53. BCC of the skin is the most common skin tumour and is associated with mutational inactivation of the PTCH1 tumour suppressor gene (and less frequently oncogenic activation of SMOOTHENED). Although BCC does not appear to stem from precursor lesions - though mouse models of BCC display areas of basaloid hyperproliferation - and it is relatively stable at the genomic level, we sought to determine if these unique tumours display any characteristics of OIS. Human BCCs were positive for Senescence-associated β-galactosidase (SA-β-gal) activity (pH 6.0) and expressed known markers of senescence including DCR2, DEC1 (SHARP2) as well as the cell cycle inhibitors p15INK4b and p16INK4a. Interestingly, SA-β-gal activity was observed in stromal cells surrounding the tumour islands and this may account for why BCCs are difficult to culture in vitro as senescent cells are known to express increased levels of growth factors, cytokines and ECM proteins. To determine if OIS is associated with Hedgehog signalling in BCC, I employed a novel in vitro model of BCC created through PTCH1 suppression in human immortalised NEB1 keratinocytes. NEB1-shPTCH1 cells are viable and proliferative (albeit more slowly than control NEB1-shCON cells) and do not display SA-β-gal activity but they express higher levels of several senescent markers including DCR2 and p21WAF1. I also investigated senescence in a Mouse model of BCC in which one allele of Ptch1 is mutated and which on x-ray irradiation results in BCC formation. The expression of known markers of senescence including DCR2, DEC1 (SHARP2) as well as the cell cycle inhibitors p15INK4b, p16INK4a and p53 were all with the exception of p21WAF1 detected in these tumours. Together these data suggest that senescence is a characteristic of BCC and may explain why these tumours rarely metastasise.

Basal cell carcinoma (BCC) of the skin is predominantly associated with mutational inactivation of the PTCH1 tumour suppressor gene resulting in constitutive activation of the Hedgehog (HH) developmental pathway. Tumour formation is linked to induction of the GLI (GLI1 and GLI2) transcription factors via a pathway that is thought to require the transmembrane protein SMOOTHENED (SMO) and accordingly, SMO is attracting much interest as a drug target in cancer therapy. However, although there has been a high degree of success in treating some BCCs with anti-SMO compounds, many tumours are only partially or unresponsive which indicates that SMO-independent mechanisms may contribute to tumour formation and/or viability. To further understand how loss of (or reduced) PTCH1 function contributes to BCC, RNAi (retroviral shRNA) was employed to suppress PTCH1 in NEB1 and N/Tert immortalised human keratinocyte cells. Compared to control (shCON) cells, PTCH1 knockdown (shPTCH1) cells displayed more compact colony formation as well as increased GLI1 (but not GLI2) expression however, whereas the increase of GLI1 was suppressed upon transfection with SMO siRNA in shPTCH1 cells, it was insensitive to the presence of the SMO antagonists Cyclopamine-KAAD and SANT1 in shCON cells. The reason for this is unclear but SMO levels were increased and more nuclear in shPTCH1 cells indicating that SMO may have nuclear signalling capability that is unresponsive to certain SMO antagonists. Indeed, cDNA microarray profiling revealed that 80% of the genes that were differentially expressed in NEB1-shPTCH1 cells (>2-fold, p<0.01) remained differentially expressed in the presence of Cyclopamine-KAAD; this includes the chemokines CXCL10 and CXCL11 which were recently shown to be over-expressed in BCC thus helping validate the efficacy of NEB1-shPTCH1 cells as an in vitro tumour model. In addition, functional gene grouping has predicted novel biological processes downstream of PTCH1 that may be important in BCC biology including NF-κB signalling. In summary, the data presented in this thesis suggests that the mechanism(s) through which the loss of PTCH1 leads to BCC formation may be more complex than has been inferred from previous studies.

Tactile sensation is a complex manifestation of mechanical stimuli applied to the skin. At the most fundamental level of the somatosensory system is the cutaneous mechanoreceptor, making it the logical starting point in the bottom-up approach to understanding the somatosensory system and sensation, in general. Unfortunately, a consensus has not been reached in terms of the afferent behavior of mechanoreceptors subjected to compressive stimulation. In this study, several afferent mechanoreceptors were isolated, mechanically stimulated with controlled compressive loads. Their responses were recorded and the sensitivities of the individual receptors to compressive stimulation were statistically evaluated by correlating the compressive state of the skin to the observed“all-or-nothing" responses. A host of linear techniques have been employed previously to describe this multiple-input, binary-output system; however, each of these techniques has associated shortcomings when employed in this context. In particular, two shortcomings are the assumption of linear system input-output and the inability of the model to assess individual input-output associations relative to concurrent input in a multivariate context with interacting input. Therefore, a non-linear regression technique called logistical regression was selected for characterizing the mechanoreceptor system. From this model, the relative contributions that each component of the stimulus has upon the neural response of the receptor can be quantitatively assessed and extrapolated to the greater population of cutaneous mechanoreceptors. Since this study represents a novel approach to receptor characterization, a framework for the application of logistical regression to the time-series representation of the multiple-input, binary-output mechanoreceptor system was established and validated. Subsequently, in-vitro experiments were performed in which the afferent behavior of tactile receptors in rat hairy skin were recorded and the relative association between a number of biologically meaningful stimulus metrics and the observed neural response was evaluated for each receptor. Through the application of logistical regression, it was determined that cutaneous mechanoreceptors are preferentially sensitive to the rate of change of compressive stress when force-control stimulated and both stress and its rate of change when position-control stimulated.

With the increase of hand pathologies in the last decade, the need to better understand the anatomy of the hand is becoming more vital. The cutaneous innervation of the hand is classically described to be supplied by palmar cutaneous branch of the median nerve (PCBMN), common digital nerves (CDNs), ulnar nerve (UN), palmar cutaneous branch of the ulnar nerve, dorsal branch of the ulnar nerve (DBUN), superficial branch of the radial nerve (SBRN) and occasionally the lateral antebrachial cutaneous nerve (LABCN). Although the sensory distribution of the hand has been described in the literature, reports have often shown contradicting views and occasionally different or incomplete descriptions. Furthermore, clinical procedures in the hand and wrist can result in painful and/or disabling postoperative complications. This thesis outlines, categorizes and describes the distribution and branching patterns of cutaneous branches supplying the palmar and dorsal surface of the hand and their relationship to the distal area of the forearm and wrist. It also investigates the palmar and dorsal communicating branches, their patterns and common locations. Moreover, the project discusses the impact of the distribution and branching patterns of the cutaneous nerves on surgical and diagnostic procedures performed in the hand, wrist and distal forearm. 160 cadaveric hands were dissected in the Centre for Anatomy and Human Identification (CAHID), University of Dundee. All cadavers were musculoskeletally mature adults with mean age of 82.5±9.4 (range: 53-101) years. Skin was removed from the distal half of the forearm to the metacarpophalangeal joints. Nerves under investigation were identified, dissected, and traced. Sketches, photographs, and measurements to predefined landmarks including the wrist crease (WC), bistyloid line (BSL) and the third metacarpophalangeal (MCP) joint were taken and results expressed as means, standard deviations and ranges. Patterns are classified and expressed with frequencies. The PCBMN was found to originate from the main trunk of the median nerve (MN) 54.1±15.7 mm proximal to the WC and course distally between flexor carpi radialis and palmaris longus (if present) to innervate the proximal palmar surface of the hand by branching into one of three types identified. Furthermore, two PCBMN were found in 8.9% of cases. The second, third, fourth CDNs were found to divide into proper digital nerves at a point located distal to the 70% of the distance between the third MCP joint and the BSL in 88% of cases. The cutaneous innervation of the palm was found to be relatively constant with the lateral 3½ digits being supplied by the MN and the medial 1½ being supplied by the UN. A palmar CB was found between the third CDN-MN and fourth CDN-UN in 86.9% of the cases coursing in different patterns and changing the palmar sensory innervation of that previously described. The sensory innervation of the dorsum of the hand was variable. The most common pattern was being supplied by the SBRN innervating the lateral dorsal skin and the skin covering the lateral 2½ digits and the DBUN innervating the medial dorsal skin and the skin covering the medial 1½ digits found in 37.3%. All radial supply to the dorsum of the hand with the absence of the DBUN was found in 6.7%. The SBRN connected with the LABCN in 30.7% and with the DBUN in 26.4% complicating the sensory innervation in the dorsum of the hand. Understanding the cutaneous innervation of the hand, appreciation of the possible variations and presence of communicating branches will result in a better evaluation of signs and symptoms, establishing a proper therapeutic plan, avoiding iatrogenic injuries during surgical interventions, and properly diagnose postoperative complications leading to an increased quality of medical service and patient satisfaction.