Photodynamic therapy (PDT) is a form of cancer treatment involving light, a photosensitizer and oxygen, whereby the photosensitizer is preferentially taken up by tumour cells, excited when exposed to light of the appropriate wavelength, and generates cytotoxic excited singlet oxygen that damages and destroys cells. Photofrin is the only approved photosensitizer for clinical use in treating esophageal and early and late lung cancers in the U.S., Canada and several other countries. Despite its effectiveness in treating some tumour types, Photofrin use has some limitations and thus photosensitizers are continuously being studied to find more efficient ways of killing tumour cells. Previous reports have described the isolation of photodynamic therapy resistant human colon carcinoma HT29 cells. HT29/P14, HT29/All and HT29/N8 were isolated by repeated in vitro PDT treatment to the 1-10% survival level followed by regrowth of single surviving colonies using the photosensitizers Photofrin, Aluminium Phthalocyanine Tetrasulphonate (AlPcS4) and Nile Blue A respectively. These PDT resistant HT29 variants all display increased levels of BNip3, Bcl-2 and the heat shock protein 27 (Hsp 27), but decreased levels of Bax and the mutant HT29 p53 protein. Since mutant p53 and increased expression of Hsp27 and Bcl-2 and have been associated with resistance to various chemotherapeutic agents in some tumour cells, whereas Bax and BNip3 are potent inducers of apoptosis, it was considered of interest to examine the sensitivity of these PDT resistant HT29 variants to other cytotoxic agents. Cell sensitivity to ultraviolet (UV) A radiation (UV A), a mixture of UV A and UVB (UV AlB), UVC, or cisplatin was determined by a comparison of the D37 values for clonogenic survival in the variants compared to that in parental HT29 cells. The HT29 PDT resistant variants were not cross-resistant to cisplatin or UVC. In contrast, HT29/P14, HT29/All and HT29/N8 all showed a significant increase in cisplatin sensitivity, while HT29/All cells also showed a significant increase in UVC sensitivity. HT29/N8, and HT29/P14 both showed a significant increase in UVA resistance compared to HT29 cells whereas HT29/All did not. HT29/P14 was the only POT-resistant cell line significantly cross-resistant to UVA/B relative to HT29. While HT29/P14 and HT29/All both showed a slight increase in resistance to Photofrinmediated PDT compared to HT29/Parental, this increase was only significant for HT29/All. However, HT29/N8 was significantly more sensitive to Photofrin-mediated PDT than HT29/Parental. To complicate matters, clonogenic variability was observed amongst the two HT29 sources examined, since one of the original HT29 cell lines showed a significantly higher resistance to Photofrin-mediated PDT compared to the other parental HT29 cells that were used to derive the PDT -resistant cell lines. To examine if the differences in sensitivity of the PDT-resistant cell lines compared to parental HT29 cells in response to cisplatin and UV radiation were due to differences in DNA repair, host cell reactivation (HCR) experiments were performed with a UVC damaged B-galactosidase reporter gene from the adenovirus Ad5HCMVSp1LacZ. HCR ofthe UV-damaged reporter gene was reduced in HT29/All (the cell line most sensitive to UVC) compared to the parental HT29 cells at high multiplicities of infection of the virus. This suggests the possibility of a decreased DNA repair capacity for HT29/ A 11 cells. However, due to differences in cellular morphology between HT29 and HT29/All cells, as well as possible differences in expression of the reporter gene, it was inconclusive that the difference in HCR reflects a true difference in DNA repair between HT29 and HT29/All cells. Hsp27 over expression alone was not responsible for the increased cisplatin sensitivity of the HT29 PDT resistant variants since there was no correlation of Hsp27 protein expression levels to l/D37 (used as a measure of sensitivity), for the cisplatin colony survival assays. In addition, Hsp27 protein expression levels did not correlate with UVC, cisplatin or UV A sensitivity suggesting that Hsp27 may be uniquely involved in making cells more resistant to PDT. p53 but not BNip3 protein levels correlated with sensitivity of cells to UV A, whereas no correlation was observed between p53 or Hsp27 protein expression levels and UVC sensitivity. p53 and p21 protein levels were not altered in either parental HT29 or the HT29/P14 POT-resistant variant following UVC and cisplatin exposure, respectively. In addition, introduction of wild-type p53 (using infection of a replication deficient adenovirus vector encoding the wild-type p53 gene), into parental HT29 or the PDT -resistant HT29/P 14 variant, had no effect on cisplatin sensitivity compared to cells infected with a control adenovirus vector expressing the LacZ gene. Taken together, these results suggest that the increased sensitivity of the PDT resistant variants to cisplatin did not result from differences in p53-dependent cisplatininduced cell cycle arrest. A strong correlation of cellular cisplatin sensitivity to the ratio of BNip3 to p53 protein levels, suggests that alterations in the expression of several different genes, including a reduced expression of the mutant HT29 p53 protein and an increased expression of BNip3, contribute to the increased cisplatin sensitivity of the HT29 PDT resistant variants. It has been reported previously that apoptosis induced by BNip3 is significantly inhibited by both wild type and mutated p53. Since pro-apoptotic BNip3 is over expressed in all three PDT-resistant HT29 cell lines, and BNip3/p53 protein expression levels were correlated to cisplatin sensitivity, this suggests that cisplatin kills HT29 cells through a BNip3-mediated apoptotic pathway. / Thesis / Master of Science (MS)

No / Raman spectra of an extremophile cyanobacterial colony in hydromagnesite from Lake Salda in Turkey have revealed a biogeological modification which is manifest as aragonite in the stratum associated with the colony. The presence of key spectral biomarkers of organic protectant molecules such as (8-carotene and scytonemin indicate that the survival strategy of the cyanobacteria is significantly one of UV-radiation protection. The terrestrial location of this extremophile is worthy of consideration further because of its possible putative link with the White Rock formations in Sabaea Terra and Juventae Chasma on Mars.

No / Ultraviolet radiation (UVR) in sunlight has deleterious effects on skin, while behavioural changes have resulted in people gaining more sun exposure. The clinical impact includes a year-on-year increase in skin cancer incidence, and topical sunscreens alone provide an inadequate measure to combat overexposure to UVR. Novel methods of photoprotection are being targeted as additional measures, with growing interest in the potential for systemic photoprotection through naturally sourced nutrients. Omega-3 polyunsaturated fatty acids (n-3 PUFA) are promising candidates, showing potential to protect the skin from UVR injury through a range of mechanisms. In this review, we discuss the biological actions of n-3 PUFA in the context of skin protection from acute and chronic UVR overexposure and describe how emerging new technologies such as nutrigenomics and lipidomics assist our understanding of the contribution of such nutrients to skin health.

Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-09-19T14:46:51Z No. of bitstreams: 2 Tese - Rangel Magalhães Luzin - 2018.pdf: 3753425 bytes, checksum: 3ac739156d95f6ef2de370e5c5ce093c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-09-20T11:32:29Z (GMT) No. of bitstreams: 2 Tese - Rangel Magalhães Luzin - 2018.pdf: 3753425 bytes, checksum: 3ac739156d95f6ef2de370e5c5ce093c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-09-20T11:32:29Z (GMT). No. of bitstreams: 2 Tese - Rangel Magalhães Luzin - 2018.pdf: 3753425 bytes, checksum: 3ac739156d95f6ef2de370e5c5ce093c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-08-29 / It is known that sun exposure is one of the factors that contribute greatly to the appearance of skin cancer. Cancer cases have arisen annually on the planet and many of these cases have direct correlation with sun exposure. Knowing that both UVA and UVB radiation are harmful to health when the person is overexposed, the need arises for the use of devices to protect the skin and one of these ways and already recognized by the scientific community is through the prophylactic use of protectors solar power. Thus, this work proposes the synthesis, structural characterization, thermal stability verification, molar absorptivity calculation and in vitro UVB protection factor (PFUVB) calculated by the spectrophotometric method described by Mansur of new compounds derived from structures analogous to natural products. The structural planning was based on triazine derivatives (they are already commercially used with relative efficiency) and the use of chalcones, which are structures that besides having double bonds and conjugated aromatic structures that favor the absorption of the ultraviolet radiation, are studied compounds for various purposes and present in various plants, thus constituting a natural structure. In the planning, the choice of such structures was also due to the synthesis of compounds of high molar mass (above 900 daltons), contributing to safe structures, with low toxicity probability, low skin permeation and in compliance with the demands of the current legislation. The data obtained in the work reinforce the success of the same, where we had for the prototypes synthesized, molar absorptions superior to commercial filters. Establishing a​​research with the use of chalcones in safe and efficient sunscreens. / É sabido que a exposição solar é um dos fatores de grande contribuição para o surgimento do câncer. Casos de câncer tem surgido anualmente no planeta e muitos desses casos tem direta correlação com a exposição solar. Sabendo que tanto a radiação UVA quanto a UVB são nocivas à saúde quando o indivíduo é exposto em demasia, surge a necessidade do uso de artifícios para a proteção da pele e uma dessas maneiras e já reconhecida pelo meio científico é através do uso profilático de protetores solares. Assim este trabalho se propôs a síntese, caracterização estrutural, verificação de estabilidade térmica, cálculo de absortividade molar e fator de proteção solar UVB (FPUVB) in vitro calculado pelo método espectrofotométrico descrito por Mansur de novos compostos derivados de estruturas análogas a produtos naturais. O planejamento estrutural foi baseado nos derivados triazínicos (pois já são de uso comercial com relativa eficiência) e o uso de chalconas, que são estruturas que além de possuir duplas ligações e estruturas aromáticas conjugadas que favorecem a absorção da radiação ultravioleta, são compostos bastante estudados para diversos fins e presente em vários vegetais, constituindo assim uma estrutura natural. No planejamento, a escolha de tais estruturas se deu também pela síntese de compostos de alta massa molar (acima de 900 Daltons), contribuindo para estruturas seguras, com probabilidade de baixa toxicidade, baixa permeação cutânea e atendendo aos reclames das legislações vigentes. Os dados obtidos no trabalho reforçam o sucesso do mesmo, onde tivemos para os protótipos sintetizados, absorções molares superiores a filtros comerciais. Estabelecendo assim uma nova linha de pesquisas com a utilização de chalconas em filtros solares seguros e eficientes.

Master of Science / Department of Chemical Engineering / Larry E. Erickson / The damage that can be inflicted by ultraviolet radiation has gained widespread interest. Traditionally sunscreens are made of organic and inorganic components that block two of the three types of ultraviolet radiation, UVA and UVB. This report is a literature review of several articles that have investigated the effects of inorganic UV filters; specifically titanium dioxide and cerium dioxide. There are concerns about absorption of titanium dioxide into the skin and the adverse reactions that could occur, but it was found that there is little to no absorption. Similarly the photostability of titanium dioxide is a concern; this was found to be remedied in part by a surface treatment to the titanium dioxide. The combination of titanium dioxide and carnauba wax was also studied and found to enhance the properties of both the organic and inorganic filters. Ceria was studied as a possible replacement for titanium dioxide. It was found to have similar ultraviolet shielding properties while minimizing the photocatalytic activity and photocytotoxicity seen in titanium dioxide.

Thesis (MScMedSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Context: Excessive exposure to ultraviolet radiation (UV) results in the risk of acquiring long-term harmful effects such as photoaging, which is characterised by deep wrinkles, roughness, dyspigmentation and an increased loss in elasticity. As a result, the detection of photoaging at an early stage is crucial to improving morbidity, whilst preventing the advancement of skin cancer. Aim: The aim of the study was to develop and to validate a diagnostic real-time PCR method in order to establish the gene expression profiles of potential biomarkers in the skin so as to quantify the degree of photoaging: this was conducted by retrieving total RNA from cells adherent to tape strips from sun exposed and non-exposed skin areas. Materials and methods: Twenty healthy volunteers consisting of seven males and thirteen females aged 25 to 67 years were included in this study. Tape stripping was performed using pre-cut D-Squame® 22 mm adhesive discs. Samples were collected on the right medial thigh area 20 cm above the patella and 2 cm below the lateral canthus of the right eye. Total RNA was extracted and relative standard curve method of gene expression was performed. TGF-β, MMP 9, TNF-α and IL-6 mRNA transcripts were selected as representative cytokines to determine the relative fold-change in sun exposed and non-exposed areas of the skin so as to determine extent of photoaging. Results: Repeatability and reproducibility was determined by the coefficient of variation (CV) was within an acceptable range. Thirty five percent (n=7) samples displayed down-regulatory effects for TGF-β. Down regulation of MMP 9 was observed within 30% (n=6) of samples, while 15% (n=3) showed marked up regulation. Only two samples showed measurable levels of TNF-α in the assay, of which one showed significant up regulation. Furthermore, we were unable to detect any IL-6 expression in any of the samples prepared. Conclusion: we have shown that epidermal cytokines can be retrieved from tape stripped samples and can be quantified via real-time PCR. However, the choices of cytokine biomarkers reveal that they are as important as the concentration of starting material. In this study cytokines such as IL-6 is not as informative in determining the extent of photoaging without high doses of ultraviolet radiation before sample collection as opposed to the other explored cytokines. / AFRIKAANSE OPSOMMING: Konteks: Oormatige blootstelling aan ultraviolet (UV) bestraling kan tot ‘n risiko van skadelike en lantermynse nagevolge lei wat gekenmerk word deur foto-veroudering. Dit sluit in diep plooie, growwe vel en ‘n toenemende verlies in elastisiteit. Die ontdekking van foto-veroudering op ‘n vroeë stadium is van kardinale belang vir die verbetering van morbiditeit en die voorkoming van velkanker bevordering. Doelstelling: Die doel van hierdie studie was om ‘n diagnostiese polimerase kettings reaksie (PKR) metode te ontwikkel om geen uitdrukkings profiele van potensiële bio-merkers te vestig in die vel, om so die graad van foto-veroudering in areas van vel wat blootgestel word aan die son en beskermde van die son te bepaal deur totale RNS te versamel van kleeflintskyfies. Materiale en metodes: Twintig gesonde vrywilligers (sewe mans en dertien vroue), tussen die ouderdom van 25 en 67 jaar, was ingesluit in hiedie studie. Vel monsters was versamel deur gebruik te maak van Dsquame® 22 mm kleeflintskyfies 20 cm bokant die patella van die regterkanste mediale heup en 2 cm onder die regter oog. Totale RNS was geisoleer en die relatiewe vlak van geen uitdrukking was bepaal deur gebruik te maak van die kurwe model. Die boodskapper ribonukleiosier transkripsies van die sitokiene TGF- β, MMP 9, TNF-α en IL-6 was gekies as verteenwoordigers van foto-veroudering om die relatiewe verandering van foto-veroudering in die vel te bepaal. Resultate: Validering metodes was aanvaarbaar. ‘n Afwaarts reguleringseffek in TGF-β en MMP 9 merker uitdrukking is gevind in vyf en dertig persent (n=7) en dertig persent (n=6) van monsters, onderskuidelik. In vyftien persent (n=3) van monsters is ‘n opwaarts reguleringseffek in die laasgenoemde gevind. Slegs twee monsters het meetbare vlakke van TNF-α getoon in die eksperiment, waarvan slegs een ‘n noemenswaardige opwaartse regulering getoon het. IL-6 uitdrukking is nie gevind in enige van die monsters. Gevolgtrekkings: Hierdie studie het bepaal dat sitokiene van die vel geisoleer van kleeflint monsters en gekwantifiseer deer relatiewe PKR uitdrukking bepaal kan word. Die keuse van bio-merkers is egter net so belangrik as konsentrasie bepaling van die monsters. Die IL-6 sitokien, in vergelyking met ander, is slegs informaliet tydens hoë ultraviolet bestraling aan die vel blootgestel is.

The temperature-programmed desorption profiles of water from three lunar analogs were measured. These experiments showed that glassy materials were hydrophobic, that water on multiphase materials occupied a continuum of adsorption sites, and that feldspar exhibited significant chemisorption of water. The competition between photodissociation and photodesorption of amorphous solid water (ASW) was investigated on three substrates: copper with a thin oxide coating, an impact melt breccia from Apollo 16, and a mare basalt from Apollo 17. The rotational temperature of desorbing H₂O did not vary significantly with substrate, but the H₂O time-of-flight spectra were broader on the lunar slabs than on copper. Additionally, the cross sections for water removal at low coverages were higher on the lunar slabs than on copper. O(³PJ) produced by 157-nm irradiation of ASW on the same three substrates was measured as a function of spin-orbit state, H₂O exposure, and irradiation time. The same Maxwell-Boltzmann components were present in each case, with translational temperatures of 10,000 K, 1800 K, 400 K, and the surface temperature, but the relative intensities of these components differed widely between substrates. Evidence for diffusion out of pores in the ASW and in the lunar slabs was observed for H2O exposures of at least 1 Langmuir. Cross sections for H2O and O(3PJ) depletion due to 157-nm irradiation of ASW were applied to icy grains in the rings of Saturn, and corresponding cross sections on the lunar substrates were used to estimate the flux of water desorbing from the Moon and the density of oxygen atoms in the lunar atmosphere.

Thesis (PhD (Physics))--University of Stellenbosch, 2006. / Carbon monoxide (CO) is a diatomic molecule of particular interest in astrophysics, due to its high abundance in interstellar space. The Fourth Positive System A1Π−X1Σ+ of CO is an important feature in the vacuum ultraviolet (VUV) region of the electromagnetic spectrum in astronomical observations, especially in high-resolution spectra recorded by satellite-based spectrographs. The interpretation of these astronomically detected spectra requires accurate laboratory wavelengths to serve as rest wavelengths and to resolve possible Doppler-shifts. Such rest wavelengths are known for the 12C16O, 13C16O and 12C18O isotopomers for all astronomically observed spectral lines of the Fourth Positive System. The only laboratory wavelengths currently available for the Fourth Positive System of the 12C17O isotopomer have been determined in a previous work carried out in our laboratory for the vibronic band A1Π(v0 = 3)−X1Σ+(v00 = 0). The present study continues this work for the other vibronic bands which have been detected astronomically, namely A1Π(v0 = 2 − 5)−X1Σ+(v00 = 0). The A1Π(v0 = 0− 1)−X1Σ+(v00 = 0) vibronic bands have also been investigated due to their probability for future astronomical detection. Rotationally-resolved spectra of these six vibronic bands were obtained by selective rovibronic laser excitation, and subsequent detection of the undispersed fluorescence, observed as a function of the excitation wavelength in the VUV. A tunable narrow-bandwidth VUV laser source is used for excitation, and the CO gas sample is introduced by supersonic expansion. Flow-cooling in the supersonic expansion to rotational temperatures roughly corresponding to temperatures in the interstellar medium simplifies and aids the spectral analysis of the spectral lines of interest. The cold conditions in the supersonic expansion facilitates a high sensitivity for detection of the low-J lines, and allows the detection of rare isotopomers of CO in natural abundance. The experimental setup has been improved in the present study by the addition of a vacuum monochromator, facilitating an improved characterisation of the VUV source. Furthermore, a number of experimental conditions have been optimised for the detection of rare CO isotopomers, significantly increasing the signals of these lines in the spectra. The combination of this increase in sensitivity and the addition of the vacuum monochromator to the experimental setup, allowed the simultaneous detection of absorption spectra with the fluorescence spectra as an additional source of information in spectral analysis. The increased sensitivity also contributed to the detection of a large number of spectral lines of interest, with some additional lines identified in the previously studied vibronic band. Spectral lines of 12C16O, 13C16O, 12C18O and 12C17O were detected in each vibronic band, allowing accurate calibration of the spectra. A total of 29 new lines of 12C17O were recorded in the six vibronic bands investigated. Additionally, 10 new singlet-triplet lines of 12C16O were recorded in the wavelength regions investigated. The new wavelengths of 12C17O have been applied to calculate consistent heliocentric velocities of a gas cloud toward the star X Persei, obtained from spectra of the different CO isotopomers taken by the Hubble space telescope.

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