Perspective: Evolution of Human Skin Color: How Low Levels of Vitamin D Drove Natural Selection

2012 ◽  
pp. 25-37 ◽  
Author(s):  
Scott T. Weiss
2008 ◽  
Vol 41 (18) ◽  
pp. 16
Author(s):  
DIANA MAHONEY
Keyword(s):  

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1640.2-1640
Author(s):  
I. González Fernández ◽  
C. Álvarez Castro ◽  
C. Moriano ◽  
A. López Robles ◽  
X. E. Larco Rojas ◽  
...  

Background:Vitamin D plays an important role in the pathogenesis of autoimmune diseases, so that it has been shown that an adequate level is associated with a lower risk of developing this group of entities as well as a lower severity of them. Specifically, in spondyloarthritis (SpA) the deficiency has been associated with greater aggressiveness and greater radiological progression.Objectives:Assess levels of vitamin D in patients diagnosed with SpA in the León University Assistance Complex and study its possible relationship with different clinical-epidemiological variables.Methods:Prospective observational study between January 1, 2019 and December 31, 2019 with consecutive sampling of patients diagnosed with SpA (New York criteria, ASAS) in our hospital between 1973 and 2018. It was taken as a cut-off point for vitamin normality D those values ≥ 30 ng / ml. The disease activity was assessed based on BASDAI and CRP level (taking as a cut-off point 5 mg/l, reference value of our hospital and ruling out elevation due to intercurrent processes) in the last consultation. Positive values above 130 mlg/dL were considered for the orosomucoid and for calprotectin as undetermined values between 50-100 mg/kg feces and suspected IBD greater than 100 mg/kg feces. An attempt was made to link the value of vitamin D with disease activity, tobacco, the development of uveitis and the presence of subclinical intestinal inflammation.Results:132 patients were included, of which 60.6% were men with a mean age of 49.35 ± 12.95 years. 84.8% were B27 positive. 88.6% met New York criteria. 35.6% suffered uveitis at some time during their evolution. As for tobacco, 68.2% were non-smokers, 12.9% were former smokers and 18.9% were active smokers. 6.8% of the sample presented positivity for the orosomucoid and 37.8% alterations in calprotectin (of which 24.2% were undetermined and 13.6% suspected of inflammatory bowel disease). Only 25% of patients had elevated CRP levels and 11.4% of patients had BASDAI> 4. 50.8% of our sample had optimal levels of Vitamin D while 49.2% were at low values.A statistically significant association was observed between hypovitaminosis D and elevated CRP levels (p 0.038). In our sample we found no statistical association with uveitis or with markers of subclinical inflammatory activity.Conclusion:-Almost half of the patients in our sample have hypovitaminosis D which is probably attributable to the meteorological characteristics of León region.-Low levels of vitamin D are statistically significantly related to higher levels of CRP and, therefore, with greater disease activity.-No significant relationship was found with uveitis or with a higher risk of subclinical intestinal inflammation in our simple.References:[1]Castro Domínguez F, Salman Monte TC, Blanch Rubió J. Vitamin D in rheumatic diseases.Rev Osteoporos Metab Miner. 2017; 9 (1) supplement: 31-39.Disclosure of Interests:None declared


Author(s):  
Grace L. Samson ◽  
Joan Lu

AbstractWe present a new detection method for color-based object detection, which can improve the performance of learning procedures in terms of speed, accuracy, and efficiency, using spatial inference, and algorithm. We applied the model to human skin detection from an image; however, the method can also work for other machine learning tasks involving image pixels. We propose (1) an improved RGB/HSL human skin color threshold to tackle darker human skin color detection problem. (2), we also present a new rule-based fast algorithm (packed k-dimensional tree --- PKT) that depends on an improved spatial structure for human skin/face detection from colored 2D images. We also implemented a novel packed quad-tree (PQT) to speed up the quad-tree performance in terms of indexing. We compared the proposed system to traditional pixel-by-pixel (PBP)/pixel-wise (PW) operation, and quadtree based procedures. The results show that our proposed spatial structure performs better (with a very low false hit rate, very high precision, and accuracy rate) than most state-of-the-art models.


Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 689-703 ◽  
Author(s):  
Michael J Ford ◽  
Charles F Aquadro

Abstract We present the results of a restriction site survey of variation at five loci in Drosophila athabasca, complimenting a previous study of the period locus. There is considerably greater differentiation between the three semispecies of D. athabasca at the period locus and two other X-linked genes (neon-transient-A and E74A) than at three autosomal genes (Xdh, Adh and RC98). Using a modification of the HKA test, which uses fixed differences between the semispecies and a test based on differences in Fst among loci, we show that the greater differentiation of the X-linked loci compared with the autosomal loci is inconsistent with a neutral model of molecular evolution. We explore several evolutionary scenarios by computer simulation, including differential migration of X and autosomal genes, very low levels of migration among the semispecies, selective sweeps, and background selection, and conclude that X-linked selective sweeps in at least two of the semispecies are the best explanation for the data. This evidence that natural selection acted on the X-chromosome suggests that another X-linked trait, mating song differences among the semispecies, may have been the target of selection.


PLoS ONE ◽  
2012 ◽  
Vol 7 (6) ◽  
pp. e38934 ◽  
Author(s):  
Louise Jeanette Pauline Persson ◽  
Marianne Aanerud ◽  
Pieter Sicco Hiemstra ◽  
Jon Andrew Hardie ◽  
Per Sigvald Bakke ◽  
...  

2011 ◽  
Vol 55-57 ◽  
pp. 77-81
Author(s):  
Hui Ming Huang ◽  
He Sheng Liu ◽  
Guo Ping Liu

In this paper, we proposed an efficient method to address the problem of color face image segmentation that is based on color information and saliency map. This method consists of three stages. At first, skin colored regions is detected using a Bayesian model of the human skin color. Then, we get a chroma chart that shows likelihoods of skin colors. This chroma chart is further segmented into skin region that satisfy the homogeneity property of the human skin. The third stage, visual attention model are employed to localize the face region according to the saliency map while the bottom-up approach utilizes both the intensity and color features maps from the test image. Experimental evaluation on test shows that the proposed method is capable of segmenting the face area quite effectively,at the same time, our methods shows good performance for subjects in both simple and complex backgrounds, as well as varying illumination conditions and skin color variances.


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