Search results for "PIGMENT"
showing 10 items of 626 documents
Responses to ultraviolet radiation in larval pike, Esox lucius, of two origins and ages
2007
Ultraviolet radiation (UVR)-induced mortality and behavioural disorder were studied in larval northern pike of two origins and ages. Newly hatched larvae of two differently coloured populations and six-day-old larvae of one population were exposed to four fluence rates of UVR, resulting in total doses from 11.5 to 63 kJ m–2, and monitored for mortality and behaviour. The rate of mortality and the severity of behavioural disorder differed by origin and age of the animals, but the effect was fluence-rate dependent. Total melanin concentration of newly hatched larvae was measured to assess if sensitivity to UVR correlated with pigmentation, but no differences in melanin concentration between l…
Znaczenie roślinnych i syntetycznych składników aktywnych we wspomaganiu procesu depigmentacji skóry
2021
Melanogenesis is a process catalyzed by tyrosinase enzyme leading to synthesis of two types of pigment in the skin: black-brown eumelanin and red-yellow pheomelanin. Pheomelanin is synthesized in the second stage of melanosome maturation, while eumelanin-synthesizing melanosomes are inactive. The black-brown pigment is produced in the third stage of melanosome development. The last, fourth stage of melanosome maturation is characterized by low tyrosinase activity, which reflects the low pigment production in the skin. The process of skin pigment production (melanogenesis) is mainly regulated by solar radiation, hormones and other endo- and exogenous factors. Over- stimulated melanogenesis l…
Oral melanoacanthoma and oral melanotic macule: a report of 8 cases, review of the literature, and immunohistochemical analysis.
2007
Oral melanoacanthoma (MA) is a rare, benign pigmented lesion, similar to cutaneous MA, characterized by hyperplasia of spinous keratinocytes and dendritic melanocytes. The pathogenesis of oral MA remains uncertain, although its clinical behavior is suggestive of a reactive origin. The most common intraoral sites are the buccal mucosa, lip, palate and gingiva. The average age of presentation is 28 years, mainly in blacks, with a strong female predilection. The oral melanotic macule (MM) is a small, well-circumscribed brown-to-black macule that occurs on the lips and mucous membranes. The etiology is not clear and it may represent a physiologic or reactive process. The average age of presenta…
An Iranian booklet: non destructive examination by Energy Dispersive X-Ray Diffractometry and Micro-Raman Spectroscopy
2009
Energy Dispersive X-Ray Diffractometry was used in combination with micro-Raman Spectroscopy to study an undated illuminated Iranian booklet. In both cases, no preliminary preparation of the samples was needed: the data were acquired in a non-destructive way in a natural environment. The book is of particular interest because of the unusual presence of miniatures on some pages. The two techniques were used to collect data from small areas of the pages and in different regions of the miniature in order to identify inks and pigments and to attempt chronological assignment. Raman spectra were affected by strong background fluorescence. In spite of this, different peaks were detected and identi…
Caratterizzazione di pigmenti storici singoli e in miscela
2012
Characterisation of component pigments in a mixture
2011
This work is part of Raman spectra database constitution of pigments and materials of Cultural Heritage interest for polychrome artworks characterization. The colours of paintings are often obtained mixing pigments of palette artist’s. The attribution of a work of art to an author and the individuation of fakes are related to the identification of used pigments and also to the detection of mixture constituents. The main research objective is the extension of PH3DRA laboratory database with information useful to detect not only each single pigment but also quantitative data regarding its relative ratio in the examined mixture. The availability of spectra as revealed represents the primary li…
Characterization of component pigments in a mixture
2011
This work is part of Raman spectra database constitution of pigments and materials of Cultural Heritage interest for polychrome artworks characterization. The colours of paintings are often obtained mixing pigments of palette artist’s. The attribution of a work of art to an author and the individuation of fakes are related to the identification of used pigments and also to the detection of mixture constituents. The main research objective is the extension of PH3DRA laboratory database with information useful to detect not only each single pigment but also quantitative data regarding its relative ratio in the examined mixture. The availability of spectra as revealed represents the primary li…
Arthroscopic approach for treating a pigmented villonodular sinovitis of TMJ. A case report
2017
The present report describes the case of a 29-year-old man referred to our service for TMJ pain and progressive reduction of the mouth opening. Differential diagnostics included rheumatologic diseases, monoarthritis and intraarticular lumps. In this line, a face CT scan and a MRI of TMJ were carried out in order to ensure a proper diagnosis. These tests showed a solid lesion into the joint cavity. In view of that, we decided to perform a diagnostic and therapeutic arthroscopy of TMJ. Histopathological studies confirmed the diagnosis of pigmented villonodular synovitis. The main aim of this report is to describe this rare syndrome with the goal of proposing suitable treatments. Moreover, we …
Dyskeratosis congenita: Report of a case with literature review
2007
Leukoplakic lesion is not uncommon in clinical practice but its occurrence as a component of a syndrome is rare. Dyskeratosis congenita is a rare genodermatosis, which is characterized by triad of skin pigmentation, nail dystrophy and leukoplakic lesion in the oral cavity. It is important for dentists to now about Dyskeratosis Congenita because these leukoplakic lesions can spontaneously undergo malignant transformation. Majority of cases have been reported in dermatology or pediatrics literature whereas only few reports have appeared in dental literature. The purpose of reporting this case with review of recent literature is to create better awareness among dentists about the multisystem m…
Oral Blue Nevus: Case Report
2016
Abstract: Aim of this research is the description of a case of palatal blue nevus and the diagnostic and therapeutic strategies to adopt when this oral lesion occurs. Nevi are benign proliferations of nevus cells either in the epithelium or in the subepithelial stroma. Blue nevus of the oral mucosa is a rare lesion. The oral blue nevi are asymptomatic and have no malignant potential. More importantly blue nevus had to be differentiated from malignant melanoma. Because is difficult to distinguish oral melanocytic nevi from melanoma we believe that any oral lesion in question should be excised and sent for histopathologic evaluation.