Avaliar a biocompatibilidade do fio lifting biológico - fio serrilhado de poliuretana de óleo de mamona - e sua eficácia no rejuvenescimento facial. Na primeira etapa deste trabalho implantamos os fios no dorso de camundongos, que foram sacrificados com 03, 07, 15 e 30 dias com posterior análise histológica por microscopia óptica. Na segunda fase implantamos os fios na face de pacientes com flacidez dérmica e analisamos, fotograficamente e através de uma modelagem numérico-computacional o resultado (rejuvenescimento), com intervalos entre 07 e 60 dias. As análises histológicas demonstraram uma rápida integração do fio ao tecido celular subcutâneo com formação abundante de colágeno e as fotografias dos pacientes revelaram uma maior firmeza da derme e um rejuvenescimento facial, comprovados pela análise computacional. Suas características químicas e físicas e os resultados iniciais nos permitem acreditar que o fio lifting biológico - fio serrilhado de poliuretana do óleo de mamona - apresenta elevada biocompatibilidade com uma rápida integração ao tecido subcutâneo sendo uma excelente opção no rejuvenescimento facial. / Evaluate the biological lifting thread - castor oil polyurethane serrulate thread - bio-compatibility and it´s eficacy on facial rejuvenation. At first we implanted the threads in subcutaneous tissues on mice backs that were sacrificed after 03, 07, 15 and 30 days, followed by histological analysis of material by using optical microscopy. Later, implants were carried out in patients with facial dermal flaccidity, and comparisons were made through photographs between 7 and 60 days, than we made a numerical-computational modelling comparision of this photographs. Histological analysis showed a quick thread integration with the celular subcutaneous tissue by a large amount of colagen syntesis and the patients photographs showed facial rejuvenation with improvement of the skin flaccidity comproved by numerical modelling. It`s chemical and physical characteristics and the initial results allow us belive that the biological lifting thread - castor oil polyurethane serrulate thread - has good bio-compatibility and fast integration with the celular subcutaneous tissue being an excellent option for the facial rejuvenation.

Submitted by Adriana Martinez (amartinez@unoeste.br) on 2017-06-01T14:57:32Z No. of bitstreams: 1 Eveline.pdf: 680438 bytes, checksum: 5fb8af2b6ed1e1ccd9b3e015958fc2cb (MD5) / Made available in DSpace on 2017-06-01T14:57:32Z (GMT). No. of bitstreams: 1 Eveline.pdf: 680438 bytes, checksum: 5fb8af2b6ed1e1ccd9b3e015958fc2cb (MD5) Previous issue date: 2016-11-21 / The platelet-rich plasma (PRP) is a promising resource in treatment of wounds, considered a non-toxic biomaterial, which when injected in the tissue, increases its regeneration capacity by stimulating growth factors and activating angiogenesis and thus to induce synthesis of collagen. Studies confirm the effectiveness of the autologous gel source of PRP, but the homologous and heterologous gel sources are alternatives when there are no conditions for obtaining the animal's own PRP, however, unknown whether the effect of using these sources in the organization of the collagen fibers during the process scar. Therefore, this study aimed to compare the effects on healing produced after performing dermal wound in rabbits treated with different sources of platelet-rich plasma (PRP) gel (autologous, homologous and heterologous). 36 biopsies of dermal wounds have been used, experimentally induced in 18 adult rabbits, clinically healthy, of New Zealand breed (n = 9 males, n = 9 females), treated and not treated with different sources of PRP. The wounds were sanitized and treated on 0,3,7,10,14 days, and, in 17º day, a biopsy of the wound has been made, for histologic evaluation and observation of the initial phase of remodeling. In order to determine the type of collagen, the biopsy slides passed through polarization technique with dye-red Picrosirius F3BA. Results confirmed that the source of homologous PRP gel proved to be as efficient as the source of autologous PRP gel if compared healing. Other important finding in this study was that heterologous PRP gel use provided a healing process as good as those provided by autologous and homologous gel groups. As tough PRP is rich in growth factors, even these being from other animals of the same species and also of different species, it is noteworthy that even when applied serially, the different types of PRPs have not caused negative effects, as rejection, for example. It has been concluded that the heterologous and homologous sources are safe alternatives and their use contributes positively to an adequate healing process. / O plasma rico em plaquetas (PRP) é um recurso promissor no tratamento de feridas, considerado um biomaterial atóxico, que quando injetado no tecido, aumenta a capacidade de regeneração tecidual por estimular fatores de crescimento e ativar a angiogênese, e assim induzir a síntese de colágeno. Estudos comprovam a eficácia do PRP de fonte autóloga gel, porém as fontes homóloga e heteróloga gel constituem alternativas quando não há condições de obtenção do PRP do próprio animal, porém desconhece-se o efeito do uso destas fontes na organização das fibras colágenas durante o processo cicatricial. Sendo assim, o trabalho teve como objetivo comparar os efeitos na cicatrização após a realização de ferida dérmica em coelhos tratados com diferentes fontes de plasma rico em plaquetas (PRP) gel (autólogo, homólogo e heterólogo). Foram utilizadas 36 biópsias de feridas dérmicas, experimentalmente induzidas em 18 coelhos adultos, clinicamente saudáveis, da raça Nova Zelândia (n= 9 machos, n= 9 fêmeas), tratados e não tratados (controle) com diferentes fontes de PRP. As feridas foram higienizadas e tratadas nos dia 0,3,7,10,14 e no 170 dia foi realizada a biópsia da ferida, para avaliação histológica e observação da fase inicial de remodelação. Para a determinação do tipo de colágeno, as lâminas de biópsia passaram pela técnica de polarização com o corante Picrosirius-red F3BA. Os resultados comprovaram que a fonte de PRP homólogo gel mostrou-se tão eficiente quanto a fonte de PRP autólogo gel em comparação a cicatrização. Outro importante achado no presente estudo foi que o uso PRP heterólogo gel proporcionou um processo de cicatrização tão bom quanto àqueles proporcionados pelos grupos autólogo e homólogo gel. Como o PRP é rico em fatores de crescimento, mesmo estes sendo de outros animais da mesma espécie e também de espécies diferentes, vale ressaltar que, mesmo quando aplicadas de forma seriada, as diferentes fontes de PRP não ocasionaram efeito negativo como, por exemplo, complicações clínicas. Conclui-se que as fontes heteróloga e homóloga são alternativas seguras e que seu uso contribui positivamente para um processo cicatricial adequado.

La peau est un organe se trouvant à l’interface de notre organisme et de notre environnement. Ellesubit un vieillissement qui se traduit par des modifications affectant ses différentes couches. Parmi celles-cile derme est particulièrement affecté. Les fibroblastes, présents dans le derme, synthétisent des moléculesde la matrice extracellulaire ainsi que des enzymes de dégradation. Lors du vieillissement, cette sécrétionest modifiée favorisant ainsi la sécrétion d’enzymes et la dégradation du derme. L’un des objectifs de ces travaux de thèse est d’évaluer les modifications ayant lieu chez les fibroblastes lors du vieillissement. Pour cela, trois modèles de vieillissement de fibroblastes primaires dermiques humains ont été développés et caractérisés. Une étude transcriptomique a été réalisée par PCR quantitative en temps réel et a permis de mettre en évidence des différences d’expression de gènes codant pour des composants du derme. Dans le but de développer des actifs cosmétiques à visée « anti-âge », des extraits riches en polysaccharides ont été réalisés à partir de plantes et de microorganismes, puis leur efficacité a été évaluée sur des modèles de peaux humaines. L’appareil de Golgi est un organite jouant un rôle majeur dans la modification post-traductionnelle et la sécrétion. La modification structurale de celui-ci lors du vieillissement a été évaluée sur les modèles de fibroblastes en utilisant des techniques de microcopie optique et électronique. Les résultats montrent une altération de la morphologie du réseau trans-golgien chez les fibroblastes sénescents, l’un des modèles développés au cours de ces travaux. Chez ces cellules, le TGN présente une morphologie particulière qui s’étend dans le cytoplasme. Ainsi, lors de la sénescence, nous avons pu révéler par le biais d’une étude transcriptomique que l’expression de gènes impliqués dans la structure et la fonctionnalité de l’appareil de Golgi étaient modifiée. Les résultats obtenus lors de cette thèse ont permis de mettre en évidence de nouveaux marqueurs biologiques innovants pour le criblage d’actifs dermo-cosmétiques à visée «anti-âge». / Skin is an important organ of the human body representing a protective structure in direct contactwith the external environment. During aging, skin undergoes dramatic changes including alteration ofdermal cells and components. Among these, fibroblasts synthetize and secrete a large variety ofcomponents and degrading enzymes involved in the modulation of dermal structure and functions. It isestablished that modification of the secreted components and enzymes during aging is related to dermisdegradation. This work aims to characterize aging-related alteration in fibroblasts. For this purpose, three aged human dermal primary fibroblast models have been developed. A transcriptomic study, using real-time quantitative PCR, has also been undertaken and has shown modifications in the expression of genesencoding dermal proteins. Using these results and in order to develop “anti-aging” cosmetic ingredients, extracts from polysaccharides-rich plant and microbial cells have been prepared and their efficiency evaluated on skin explants.As the Golgi apparatus is a major organelle of the secretory pathway, its structural organization has been investigated in fibroblasts using microscopy. The data show a marked alteration of trans-Golgi network morphology in aged cells. In contrast to its small and compact structure in young cells, the trans-Golgi network displays a large and expanded configuration in senescent cells. In addition, a transcriptomic analysis reveals that the expression of some genes, related to Golgi shape and/or function, is significantly modified in senescent cells. These genes could be then, used as innovating targets for the screening of novel dermo-cosmetic products with anti-aging activity.

Charles University, Faculty of Pharmacy in Hradec Králové Department of Department of Pharmaceutical Technology Candidate Mgr. Anna Nováčková Supervisor doc. Mgr. Jarmila Zbytovská, Dr. rer. nat. Title of Doctoral Thesis Study of substances affecting permeability of the skin barrier The skin barrier plays a vital role in protecting the human body and enables mammals' life on dry land. The epidermis has the primary barrier function due to several cells' layers, which gradually differentiate to their final stage, the stratum corneum (SC). SC is formed by stratified keratinocytes (known as corneocytes) surrounded by a lipid matrix. This intercellular matrix consists of an approximately equimolar ratio of ceramides, free fatty acids and cholesterol. These are particular substances formed in the epidermis from their precursors during the keratinocyte's differentiation, and their arrangement into the multilamellar structure is essential for the impermeability of the skin barrier. However, some substances or factors can disrupt the skin barrier. It is usually an undesirable process of lipid disbalance resulting in disorders or diseases of the skin barrier. On the other hand, specific substances have been developed for a reversible disruption of the skin barrier (so-called enhancers) to allow drug...

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Pour bien comprendre comment les espèces actuelles ont évolué, il est important d’étudier certains groupes clés. Ces groupes clés sont parfois bien négligés au profit d’autres groupes apparentés. L’embranchement Hemichordata forme, avec Echinodermata, le clade Ambulacraria. Ce dernier, avec l’embranchement Chordata, forme le super-embranchement Deuterostomia. Parmi les deutérostomes, la classe d’hémichordé Enteropneusta est souvent considérée comme étant la plus ressemblante au dernier ancêtre commun des deutérostomes. Les entéropneustes partagent en effet plusieurs caractéristiques avec Chordata et Ambulacraria et en étudiant celles-ci on peut reconstruire et comprendre leurs états ancestraux. Dans le chapitre d’introduction, j’aborde la morphologie générale des hémichordés et leurs relations évolutives avec les deux autres embranchement deutérostomes. Je présente aussi les caractéristiques qu’ils partagent avec les échinodermes et les cordés. J’aborde ensuite les formes que prennent les parties dures chez les animaux et en particulier chez les deutérostomes. Dans le chapitre deux, j’examine et décris la forme et la composition chimique des osselets chez huit espèces d’hémichordé. Cette étude représente un énorme bond dans nos connaissances sur la biominéralisation chez les hémichordés, car jusqu’à présent les osselets n’avaient été décrits que chez deux espèces, et la composition chimique déterminée chez une seule d’entre elle. J’interprète également ces données dans un contexte évolutif, car les osselets d’hémichordé sont probablement homologues au squelette des échinodermes. Ce chapitre est important, car il nous donne une hypothèse sur l’origine des osselets chez le dernier ancêtre commun des ambulacraires. Dans le chapitre trois, je quantifie l’asymétrie dans les fentes pharyngiennes de populations de deux espèces d’entéropneustes et d’une espèce de cordé non-vertébré. En mettant ces différents nivaux de symétrie en parallèle avec leur comportement alimentaire, les résultats supportent l’hypothèse de l’alimentation par filtration comme rôle initial des fentes pharyngiennes chez les deutérostomes et que la perte de cette fonction induit du bruit développemental, une vestigialisation ou une perte des fentes branchiales. Dans le chapitre quatre, J’utilise la micro-tomographie aux rayons-X pour décrire une espèce d’hémichordé qui était jusqu’à présent un numen nudum. Cette nouvelle technique est comparée avec l’histologie traditionnelle afin de prouver qu’elle pourrait être utilisée dans les futures études taxonomiques sur les hémichordés. Dans le chapitre cinq, je présente quelques expériences qui ont dû être exclues des chapitres précédents car elles ont donné des résultats négatifs non-publiables. Je discute des raisons pour lesquelles ces expériences ont échoué ainsi que quelques pistes de solutions possibles pour qui voudrait tenter de les refaire. Ensuite je récapitule les résultats des chapitres précédents pour montrer comment étudier les hémichordés peut encore nous apprendre beaucoup sur d’autres groupes pourtant déjà très étudiés. / The phylum Hemichordata forms, with Echinodermata, the group Ambulacraria that in turns forms with Chordata, the Deuterostomia. Among deuterostomes, the hemichordate class Enteropneusta is often viewed as the group that most closely resembles the last common ancestor of deuterostomes. Enteropneusts indeed share many traits with the other two deuterostome phyla and by studying them, we can infer the ancestral states of those traits. In the first chapter, I present the general morphology of hemichordates and their relationships with the other two deuterostome phyla. I also discuss the shared traits between the hemichordates, the echinoderms and the chordates. Last, I present the varied shapes that hard parts can take in animals, with a focus on deuterostomes. In chapter two, I describe the shape and mineral composition of ossicles in eight enteropneust species. This study is a major leap in our understanding of biomineralization in Hemichordata since up to this point ossicles were only described in two species and the mineral composition determined for only one. I discuss these results in an evolutionary context since hemichordate ossicles are probably homologous with echinoderm skeletal ossicles. This chapter is significant because it provides a hypothesis on the origin of ossicles in the last common ancestor of ambulacrarians. In chapter three, I quantify the level of asymmetry of the pharyngeal slits in populations of two species of enteropneusts and the invertebrate cephalochordate Branchiostoma floridae. We found that adults of these species display fluctuating asymmetry in the gills and that this asymmetry is lower in filter feeding. This is significant because it supports the hypothesis that filter feeding is an ancestral feature of deuterostomes and that the loss of this function increases developmental noise, vestigiality, or loss of the gills. In chapter four, I use X-ray microtomography to describe the enteropneust Balanoglossus occidentalis that was heretofore a nomen nudum. This new technique is compared with traditional histology to show that it is a viable tool in hemichordate taxonomical studies. In chapter five, I present a few experiments that had to be excluded from the other chapters because they gave negative, unpublishable results. I discuss the probable causes of their failures and potential ways to solve these issues for those who would want to pursue them further. Finally, I summarise the results of the previous chapters to show how studying hemichordates can still teach us a lot about the origin and evolution of the better studied deuterostome phyla.

Hereditary equine regional dermal asthenia (HERDA) is a recessive connective tissue disorder of Quarter Horse lineages. This study correlates previously identified decreases in skin tensile strength in HERDA with abnormal dermal collagen cross linking patterns that are also identified in urine from HERDA horses. Dermal collagen from HERDA horses has significantly less pyridinoline and significantly more deoxypyridinoline than control or carriers. Concentrations of hydroxylysine, the rate limiting substrate for these crosslinks were significantly lower in HERDA versus control and carriers. These characteristics of HERDA skin parallel humans with a similar syndrome of skin fragility, Ehlers Danlos Syndrome TypeVIA. This is the first biochemical evidence explaining the clinical skin fragility that characterizes HERDA and suggests that altered collagen lysine metabolism may be physiologically relevant to the clinical manifestation of HERDA. Evaluations of mature scars indicate that lesion and nonlesioned skin should not be viewed as biologically equivalent in HERDA investigations.

Ultraviolet radiation (UVR) in solar light is important for skin biology. It is involved in the development acute and chronic skin inflammation, aging and cancer, causing erythema, tanning and local or systemic immunosuppression. Omega-3 polyunsaturated fatty acids (n-3 PUFA) are considered anti- inflammatory and could reduce the damage caused by overexposure to UVR. Although, n-3 PUFA have been considered as photoprotective agents, their exact mechanisms of action is not completely understood. The aim of the work is to determine the effect of UVR and the n-3 PUFA eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) on human skin cells (in vitro study), specifically on: cell viability, apoptosis and their metabolism through the cyclooxygenase and lipoxygenase pathways. Also, to study the cellular incorporation and effect of n-3 PUFA on the fatty acid profile of skin cells. A clinical study was undertaken to assess the incorporation of n-3 PUFA supplements in human skin. A clinical study was performed in 40 healthy women (active group) supplemented with 4g/day of EPA (70%) and DHA (10%) and 40 healthy women (placebo group) supplemented with 4g/day of glyceryl tricoprylate coprate (GTCC). After 3 months, both blood samples and skin punch biopsies were collected and analysed for fatty acids by gas chromatography (GC). HaCaT keratinocytes and 46BR.1N fibroblasts were cultured and treated with 10 and 50μM of either EPA, or DHA or oleic acid (OA) for 72h and exposed to 15 and 50 mJ/cm2. Cell viability was measured by the MTT assay and cell apoptosis by a colorimetric method, at 24h post UVR. Cells and culture media were analysed by GC and liquid chromatography tandem mass spectrometry (LC/ESI-MS/MS) to assess cellular fatty acids and production of eicosanoids. The clinical a study showed that in RBC saturated fatty acids (SFA) (44.27±7.43%) were the main fatty acid group followed by n-6 PUFA (29.61±5.53%). While in dermal tissue monounsaturated fatty acids (MUFA) (58.90±9.80%) was the main fatty acid group followed by SFA (27.06±6.78%). A significant increase in EPA, DHA and docosapentaenoic acid (DPA) was observed in RBC but only EPA was significantly increased in the dermis post n-3 PUFA supplementation. . The viability of HaCaT keratinocytes and 46BR.1N fibroblasts decreased post UVR and this was further reduced post PUFA treatment. Cell apoptosis increased when cells were exposed to UVR and further increased when cells were treated with EPA and DHA. . In HaCaT keratinocytes MUFA (54.22±8.82%) was the main fatty acid group followed by FAS (37.11±.9.16%), while SFA (51.94±8.68%) was the main group followed by MUFA (27.07±4.79) in 46BR.1N. Treated both cells with EPA and DHA showed significant increased in cellular EPA, DPA and DHA. 46BR.1N fibroblasts produced higher levels of prostaglandins (PG) compared to HaCaT keratinocytes: PGE2 and PGD2 were the main PG in both HaCaT (7.96±3.18 and 1.48±1.19 pg/million cell; respectively) and 46BR.1N with (44.2±23.00 and 17.1±9.71 pg/million cell; respectively). Significant increase in PGE1 and PGE2 occurred when cells were exposed to 15mJ/cm2 UVR. Treatment with n-3 PUFA decreased the level of PGE1 and PGE2, and increase production PGE3 at the baseline and post UVR. Both cell lines produced hydroxy fatty acids and the concentration of these mediators was higher in 46BR.1N than HaCaT. The concentrations of these mediators were significant increased post UVR: treatment with n-3 PUFA decreased the level of HODE and HETE, and increase production of HEPE and HDHA at baseline and post UVR. Overall, n-3PUFA treatment led to increases in the content of EPA and DHA on RBC, dermal tissue and human skin cell lines. EPA and DHA in skin cell lines appear to offer protection by increasing cellular apoptosis, decreasing inflammatory mediators specifically PGE2 and 12-HETE, and increasing anti-inflammatory mediators such as PGE3, 15-HEPE and 17-HDHA.

To detect Post-kala-azar leishmaniasis (PKDL) cases, several molecular methods with promising diagnostic efficacy have been developed that involve complicated and expensive DNA extraction methods, thus limiting their application in resource-poor settings. As an alternative, we evaluated two rapid DNA extraction methods and determined their impact on the detection of the parasite DNA using our newly developed recombinase polymerase amplification (RPA) assay. Skin samples were collected from suspected PKDL cases following their diagnosis through national guidelines. The extracted DNA from three skin biopsy samples using three different extraction methods was subjected to RPA and qPCR. The qPCR and RPA assays exhibited highest sensitivities when reference DNA extraction method using Qiagen (Q) kit was followed. In contrast, the sensitivity of the RPA assay dropped to 76.7% and 63.3%, respectively, when the boil & spin (B&S) and SpeedXtract (SE) rapid extraction methods were performed. Despite this compromised sensitivity, the B&S-RPA technique yielded an excellent agreement with both Q-qPCR (k = 0.828) and Q-RPA (k = 0.831) techniques. As expected, the reference DNA extraction method was found to be superior in terms of diagnostic efficacy. Finally, to apply the rapid DNA extraction methods in resource-constrained settings, further methodological refinement is warranted to improve DNA yield and purity through rigorous experiments.

Background: Platinum group metal (PGM) mining and refining is a large constituent of the mining sector of South Africa and contributes significantly to the gross domestic product. The PGMs include the rare metals platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir) and osmium (Os). During the refining process workers are potentially exposed to various chemical forms of the PGMs via the respiratory and dermal exposure routes. Historically, emphasis has been on respiratory exposure while the extent of skin exposure is still unknown. Among the different forms of PGMs, the salts are potential sensitisers, with platinum being a known respiratory sensitiser. Workers occupationally exposed to platinum and rhodium have reported respiratory as well as skin symptoms. However, it is unknown if these metals in the salt form are permeable through human skin, and whether dermal exposure could contribute to sensitisation. Evidence regarding differences between African and Caucasian skin anatomy and structure, as well as permeation through skin is contradictory, and no information is available on metal permeation through African skin. The in vitro diffusion method has been utilised successfully in occupational toxicology to demonstrate that metals such as chromium, cobalt and nickel, to name a few, permeate through human skin. The permeability of platinum and rhodium has not been investigated previously. Aims and objectives: The research aim was to obtain insight into the permeability of platinum and rhodium through intact human skin and to provide information needed to determine the potential health risk following dermal exposure to these metals. The specific objectives included: (i) to critically review the in vitro diffusion method that is used to determine the permeability of metals through human skin, (ii) to investigate the permeation of potassium tetrachloroplatinate (K2PtCl4) and rhodium chloride (RhCl3) as representative PGM salts through intact human skin over a 24-hour period, (iii) to evaluate the difference in permeability of platinum and rhodium through intact human skin, (iv) to evaluate the difference in permeability of platinum through intact African and Caucasian human skin. Methods: Abdominal skin obtained after cosmetic procedures was obtained from five female Caucasian and three female African donors between the ages of 28 and 52 with ethical approval from the North-West University. Full thickness skin tissue was mounted in a vertical Franz diffusion cell. Skin integrity was tested by measuring the electrical resistance across the skin before and after conclusion of the experiments, using a Tinsley LCR Data bridge Model 6401. The donor solution of 32.46 mg K2PtCl4 in 50 ml of synthetic sweat (pH 6.5), and 43.15 mg RhCl3 in 50 ml of synthetic sweat (pH 6.5) was prepared. The donor solution was applied to the stratum corneum side of the skin and physiological receptor solution (pH 7.35) was added to the receptor compartment. The concentration of the metals in the receptor solution was determined by high resolution inductively coupled plasma-mass spectrometry after extraction at various intervals during the 24 hours of the study. After completion of the study, the skin was rinsed four times to remove any platinum or rhodium remaining on the skin surface. The skin was digested using hydrogen peroxide, nitric acid and hydrochloric acid during different steps to determine the mass of the metals remaining in the skin by inductively coupled plasma-optical emission spectrometry. Results: The comparison of published in vitro skin permeation studies involving metals is impeded by the variations in the experimental design and dissimilarity in the reporting of results. Differences in experimental design included, most noticeably, the use of various donor and receptor solutions, different temperatures wherein the receptor compartment was placed, differences in skin thickness and variations in exposed skin surface areas. The metals considered in the review, namely chromium, cobalt, gold, lead, mercury, nickel, platinum, rhodium and silver, permeate through intact human skin under physiological conditions. Large variations in the permeability results were observed, with the notable differences in methodology as the probable reason. Results obtained from the in vitro experiments indicate that platinum and rhodium permeated through intact Caucasian skin with flux values of 0.12 and 0.05 ng/cm2/h, respectively. The cumulative mass of platinum (2.57 ng/cm2) that permeated after 24 hours of exposure was statistically significantly (p = 0.016) higher than rhodium permeation (1.11 ng/cm2). The mass of platinum (1 459.47 ng/cm2) retained in the skin after 24 hours of exposure was statistically significantly (p < 0.001) higher than rhodium retention (757.04 ng/cm2). The comparison of permeability between two different racial groups indicates that platinum permeated through the skin of both racial groups with the flux through African skin found as 1.93 ng/cm2/h and 0.27 ng/cm2/h through Caucasian skin. The cumulative mass of platinum permeated after 24 hours of exposure was statistically significantly (p = 0.044) higher through African skin (37.52 ng/cm2) than Caucasian skin (5.05 ng/cm2). The retention of platinum in African skin (3 064.13 ng/cm2) was more than twice the mass retained in Caucasian skin (1 486.32 ng/cm2). Conclusions: The in vitro diffusion method is an applicable method to determine skin permeability of metals. However, the experimental design and format of data reporting should be standardised to enable comparison of results from different studies. Platinum and rhodium permeated through intact human skin, with platinum permeation significantly higher. African skin was significantly more permeable by platinum than Caucasian skin. Both platinum and rhodium were retained inside the skin after 24 hours of exposure, possibly forming a reservoir which could contribute to continued permeation through the skin even after removal thereof from the skin. Platinum and rhodium permeated through full thickness skin and thereby could possibly contribute to local skin symptoms such as dermatitis and urticaria found in occupationally exposed workers. By permeating through the upper layers of the skin, these metals could potentially reach the viable epidermis and contribute to sensitisation. / PhD (Occupational Hygiene), North-West University, Potchefstroom Campus, 2015