73,315 research outputs found

    Distribution of melanopsin positive neurons in pigmented and albino mice: evidence for melanopsin interneurons in the mouse retina.

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    Here we have studied the population of intrinsically photosensitive retinal ganglion cells (ipRGCs) in adult pigmented and albino mice. Our data show that although pigmented (C57Bl/6) and albino (Swiss) mice have a similar total number of ipRGCs, their distribution is slightly different: while in pigmented mice ipRGCs are more abundant in the temporal retina, in albinos the ipRGCs are more abundant in superior retina. In both strains, ipRGCs are located in the retinal periphery, in the areas of lower Brn3a(+)RGC density. Both strains also contain displaced ipRGCs (d-ipRGCs) in the inner nuclear layer (INL) that account for 14% of total ipRGCs in pigmented mice and 5% in albinos. Tracing from both superior colliculli shows that 98% (pigmented) and 97% (albino) of the total ipRGCs, become retrogradely labeled, while double immunodetection of melanopsin and Brn3a confirms that few ipRGCs express this transcription factor in mice. Rather surprisingly, application of a retrograde tracer to the optic nerve (ON) labels all ipRGCs, except for a sub-population of the d-ipRGCs (14% in pigmented and 28% in albino, respectively) and melanopsin positive cells residing in the ciliary marginal zone (CMZ) of the retina. In the CMZ, between 20% (pigmented) and 24% (albino) of the melanopsin positive cells are unlabeled by the tracer and we suggest that this may be because they fail to send an axon into the ON. As such, this study provides the first evidence for a population of melanopsin interneurons in the mammalian retina

    Antibiotic Susceptibility of Black-Pigmented \u3cem\u3eBacteroides\u3c/em\u3e Isolates from the Human Oral Cavity

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    The minimal inhibitory concentrations of penicillin and six other antibiotics were determined for 66 oral black-pigmented Bacteroides isolates by using the National Committee for Clinical Laboratory Standards proposed standard agar dilution technique. These results plus iodometric determination of β-lactamase activity showed that oral isolates of black-pigmented Bacteroides are remaining relatively susceptible to commonly used antibiotics


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    El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013. Anatomical Record, Volume 296, Special Feature — 1: P-076.The study of extracutaneous cells producing and storing melanin is of interest because it may provide valuable information about the presence of neural crest elements in internal organs and tissues. Here we report, for the first time, the presence and distribution of melanophores in the heart of a chondrichthyan species, the rabbitfish, Chimaera monstrosa. Pigment cells were found in all of 20 hearts examined. Pigment cells occur mainly in the cardiac outflow tract, which consists of two anatomical components, the proximal, myocardial conus arteriosus and the distal, non-myocardial bulbus arteriosus. A few groups of dark pigmented cells were found in the apex of the ventricle of one specimen and in the atrium of two specimens. In all instances, the melanophores were located in the subepicardial space, where they could be well recognized in both unstained and stained histological sections. The distribution and intensity of the pigmentation in the cardiac outflow tract varies markedly between individuals. In all cases, however, the pigmented area is larger on the dorsal than on the ventral surface. Dorsally, the size of the pigmented area ranges from a fringe that includes the bulbus and the distal part of the conus to the whole surface of the outflow tract. Ventrally, the pigmented area does not cover the entire conus arteriosus. The intensity of the pigmentation also varies widely; in general, it is highest at the distal portion of the conus. There is no relationship between the distribution and intensity of the pigmentation and the sex and age of the animals. The functional role of the pigmented cells is unknown. If the melanophores in the heart of C. monstrosa are indeed of neural crest origin, it would suggest a notable contribution of the neural crest cells to the cardiac outflow tract in holocephalans.Proyecto CGL2010-16417/BOS; Fondos FEDER BES-2011-04690

    By protecting against cutaneous inflammation, epidermal pigmentation provided an additional advantage for ancestral humans.

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    Pigmentation evolved in ancestral humans to protect against toxic, ultraviolet B irradiation, but the question remains: "what is being protected?" Because humans with dark pigmentation display a suite of superior epidermal functions in comparison with their more lightly pigmented counterparts, we hypothesized and provided evidence that dark pigmentation evolved in Africa to support cutaneous function. Because our prior clinical studies also showed that a restoration of a competent barrier dampens cutaneous inflammation, we hypothesized that resistance to inflammation could have provided pigmented hominins with yet another, important evolutionary benefit. We addressed this issue here in two closely related strains of hairless mice, endowed with either moderate (Skh2/J) or absent (Skh1) pigmentation. In these models, we showed that (a) pigmented mice display a markedly reduced propensity to develop inflammation after challenges with either a topical irritant or allergen in comparison with their nonpigmented counterparts; (b) visible and histologic evidence of inflammation was paralleled by reduced levels of pro-inflammatory cytokines (i.e., IL-1α and INFα); (c) because depigmentation of Skh2/J mouse skin enhanced both visible inflammation and pro-inflammatory cytokine levels after comparable pro-inflammatory challenges, the reduced propensity to develop inflammation was directly linked to the presence of pigmentation; and (d) furthermore, in accordance with our prior work showing that pigment production endows benefits by reducing the surface pH of skin, acidification of albino (Skh1) mouse skin also protected against inflammation, and equalized cytokine levels to those found in pigmented skin. In summary, pigmentation yields a reduced propensity to develop inflammation, consistent with our hypothesis that dark pigmentation evolved in ancestral humans to provide a suite of barrier-linked benefits that now include resistance to inflammation

    Pigmented coating resists thermal shock

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    Coating pigment composed of zinc oxide and potassium silicate resists the effects of thermal shock and long exposure to direct sunlight

    Pigmented melanoma cell migration study on murine syngeneic B16F10 melanoma cells or tissue transplantation models

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    Melanoma is a lethal form of skin cancer with poor prognosis, especially due to the early metastatic feature. Recent studies have shown that the melanin pigment influences the nanomechanical properties and, therefore, the metastatic behavior of the melanoma cells. We aimed to study the growth of subcutaneously transplanted syngeneic melanoma tissue in female C57BL/6 mice harvested from a mouse with a four-week B16F10 melanoma. Also, we studied the effect of the melanin pigment loading on the peritumoral migratory abilities of melanoma cells. Even when the syngeneic transplant was different (cultured cells vs. tumor tissue), the morphological features and the tumor growth were similar in both groups of mice. Heavily pigmented melanoma cells had low migration abilities. Angiogenesis, the depigmentation phenomenon, and the cell shape changes were related to pigmented melanoma cell migration along the matrix collagen fibers of peritumoral structures: the abluminal face of the vessels (angiotropism), the endomysium, and the nerves (neurotropism). The replacement of the histopathological growth pattern, the absence of angiogenesis, and rapidly tumor-bearing emboli were correlated with amelanotic and low pigmented melanoma cells. This study demonstrated that syngeneic melanoma tissue transplantation was a viable technique, and that the melanin pigment loading level can affect the melanoma cell migration profile

    Dowling-Degos Disease: Case Report and Review of the Literature

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    Dowling-Degos disease (DDD) is an unusual pigmentary disorder usually caused by mutations in keratin 5. A 44-year-old woman in good general health presented due to the recent appearance of numerous pigmented macules on her axillary and anogenital skin. A biopsy showed lacy, finger-like epidermal extensions into the dermis which were heavily pigmented and associated with tiny cysts or dilated follicles. We view DDD as part of a spectrum of disorders which are morphologically related but vary in location and time of expression. In addition, both the clinical and histological differential diagnostic considerations are extensive. Copyright (C) 2010 S. Karger AG, Base

    The HAM10000 dataset, a large collection of multi-source dermatoscopic images of common pigmented skin lesions

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    Training of neural networks for automated diagnosis of pigmented skin lesions is hampered by the small size and lack of diversity of available datasets of dermatoscopic images. We tackle this problem by releasing the HAM10000 ("Human Against Machine with 10000 training images") dataset. We collected dermatoscopic images from different populations acquired and stored by different modalities. Given this diversity we had to apply different acquisition and cleaning methods and developed semi-automatic workflows utilizing specifically trained neural networks. The final dataset consists of 10015 dermatoscopic images which are released as a training set for academic machine learning purposes and are publicly available through the ISIC archive. This benchmark dataset can be used for machine learning and for comparisons with human experts. Cases include a representative collection of all important diagnostic categories in the realm of pigmented lesions. More than 50% of lesions have been confirmed by pathology, while the ground truth for the rest of the cases was either follow-up, expert consensus, or confirmation by in-vivo confocal microscopy