Can skin histology be a useful tool for ancestry assessment in forensic settings? Ancestry assessment based on melanin pigment

Building the biological profile of a deceased person represents a pivotal step in order to achieve the victim’s identification. Specifically with regard to ancestry, the melanin distribution pattern in the dermal-epidermal layers has been poorly explored in the forensic field as a potential useful tool. In particular, nothing has been reported about the reliability of such method in bodies in active decay or in advanced state of decomposition. In this study fragments of skin sampled from bodies of known ancestry, both in good and in poor states of preservation, were subjected to histological analysis. We selected 15 subjects, which were divided into three groups: group A (5 white Europeans), group B (5 black Africans) and group C (5 Orientals). A double skin sample was performed on all the bodies, one from the abdomen and the other one from the right forearm. After histological processing and staining with hematoxylin and eosin (H&E) and Masson-Hamperl trichrome technique, the cutaneous melanin distribution pattern was assessed using a semi-quantitative score. The melanin distribution patterns observed both in fresh and in putrefied cadaveric skin were found to be in all cases consistent with the victims’ known ancestry. Moreover no differences were observed between abdominal and forearm skin samples and all the histological findings highlighted by H&E were confirmed by the Masson-Hamperl trichrome staining. We demonstrated that the histological analysis aimed at assessing the melanin distribution pattern may be a valuable useful tool in the assessment of ancestry.     

马钱苷对黑素瘤细胞与角质形成细胞共培养模型黑素合成的影响

目的：探讨马钱苷对黑素瘤细胞A375与角质形成细胞Hacat共培养模型黑素合成的影响。方法：将A375细胞和Hacat细胞构建共培养模型,以不同浓度马钱苷进行干预,通过MTY法、NaOH裂解法、多巴氧化法分别测定共培养模型的细胞增殖率、黑素含量和酪氨酸酶活性。结果：与阴性对照组相比,马钱苷10-mol／L、1016moL／L和10-7mol／L组对共培养细胞增殖率无显著性差异（P〉0．05）。马钱苷10-mol／L和10。mol／L组对共培养模型黑素合成及酪氨酸酶活性有极显著性差异（P〈0．01）。与阳性对照组相比,马钱苷10。moL／L组对共培养模型酪氨酸酶活性有极显著性差异（P〈0．01）,马钱苷10山mol／L和10。mol／L组对共培养模型黑素合成无显著差异（P〉0．05）。结论：马钱苷可能通过抑制酪氨酸酶活性减少共培养模型黑素合成。     

On the origin of the electrostatic surface potential of Aspergillus niger spores in acidic environments

The electrostatic surface potential of fungal spores is generally regarded as potentially influencing spore aggregation and pellet formation in submerged cultures of filamentous fungi. Spores of Aspergillus niger are typically characterized by negative zeta potentials over a wide range of pH values. In this study, this particular behavior is ascribed to the presence of an extensive melanin coating. It is proposed on the basis of zeta potential and pigment extraction experiments that this outermost layer affects the pH-dependent surface potential in two manners: (i) by the addition of negative charges to the spore surface and (ii) by the pH-dependent release of melanin pigment. Chemical analyses revealed that deprotonation of melanin-bound carboxyl groups is most probably responsible for pigment release under acidic conditions. These findings were incorporated into a simple model which has the ability to qualitatively explain the results of zeta potential experiments and, moreover, to provide the basis for quantitative investigations on the role of electrostatics in spore aggregation.     

Iris pigmentation and susceptibility to noise-induced hearing loss

The purpose of this retrospective study is to examine the possible association between iris pigmentation and susceptibility to noise-induced hearing loss in 2407 noise-exposed workers. The workers were between 16 to 65 years of age and were exposed to 2 to 42 years of work-related noise. Results demonstrated that dark-eyed workers presented a greater percentage of normal pure-tone thresholds than fair-eyed workers. Fair-eyed workers had threshold averages of 25.1 dB (right ear) and 26.0 dB (left ear) at 3, 4, and 6 kHz, which were significantly worse than workers with dark irises, with threshold averages of 15.8 dB and 17.2 dB in the right and left ear, respectively (p<0.01). Fair-eyed workers with less than 10 years of noise exposure had the same audiometric pattern as the dark-eyed workers exposed for more than 10 years. Workers not exposed to noise did not present significant differences in their audiometric pattern as a function of eye colour. These results suggest that iris pigmentation may be an additional indication of susceptibility to noise-induced hearing loss.     

The neuronal network responsible for paradoxical sleep and its dysfunctions causing narcolepsy and rapid eye movement (REM) behavior disorder

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by the loss of muscle atonia during paradoxical (REM) sleep (PS). Conversely, cataplexy, one of the key symptoms of narcolepsy, is a striking sudden episode of muscle weakness triggered by emotions during wakefulness, and comparable to REM sleep atonia. The neuronal dysfunctions responsible for RBD and cataplexy are not known. In the present review, we present the most recent results on the neuronal network responsible for PS. Based on these results, we propose an updated integrated model of the mechanisms responsible for PS and explore different hypotheses explaining RBD and cataplexy. We propose that RBD is due to a specific degeneration of a sub-population of PS-on glutamatergic neurons specifically responsible of muscle atonia, localized in the caudal pontine sublaterodorsal tegmental nucleus (SLD). Another possibility is the occurrence in RBD patients of a specific lesion of the glycinergic/GABAergic pre-motoneurons localized in the medullary ventral gigantocellular reticular nucleus. Conversely, cataplexy in narcoleptics would be due to the activation during waking of the caudal PS-on SLD neurons responsible for muscle atonia. A phasic glutamatergic excitatory pathway from the central amygdala to the SLD PS-on neurons activated during emotion would induce such activation. In normal conditions, the glutamate excitation would be blocked by the simultaneous excitation by the hypocretins of the PS-off GABAergic neurons localized in the ventrolateral periaqueductal gray and the adjacent deep mesencephalic reticular nucleus, gating the activation of the PS-on SLD neurons.     

In vitro fluorescence measurements and Monte Carlo simulation of laser irradiation propagation in porcine skin tissue

In dermatology, the in vivo spectral fluorescence measurements of human skin can serve as a valuable supplement to standard non-invasive techniques for diagnosing various skin diseases. However, quantitative analysis of the fluorescence spectra is complicated by the fact that skin is a complex multi-layered and inhomogeneous organ, with varied optical properties and biophysical characteristics. In this work, we recorded, in vitro, the laser-induced fluorescence emission signals of healthy porcine skin, one of the animals, which is considered as one of the most common models for investigations related to medical diagnostics of human cutaneous tissues. Differences were observed in the form and intensity of the fluorescence signal of the porcine skin, which can be attributed to the different concentrations of the native fluorophores and the variable physical and biological conditions of the skin tissue. As the light transport in the tissue target is directly influencing the absorption and the fluorescence emission signals, we performed Monte Carlo simulation of the light distribution in a five-layer model of human skin tissue, with a pulsed ultraviolet laser beam.     

白毛黑眼兔等四种实验兔黑色素分布的组织学观察与比较

目的分析包括白毛黑眼兔在内的四个品种实验兔的虹膜和皮肤组织中的黑色素分布情况和相互之间的差异。方法通过组织切片和硫酸亚铁染色,对四个品种实验兔的虹膜和皮肤组织中的黑色素含量和分布进行了观察与比较。结果与其背景白化品种相比,白毛黑眼兔不仅在虹膜组织中出现了类型完整的黑色素,而且在其表型为白色的皮肤的毛囊中也出现了低含量的黑色素。结论本结果为白毛黑眼兔突变表型机理研究提供了一定线索。     

Link between facultative melanin and tobacco use among African Americans

Nicotine's affinity for melanin-containing tissues may result from its precursor function in melanin synthesis or the irreversible binding of melanin and nicotine. The objective of this study was to investigate a hypothesized association of tobacco use, dependence, and nicotine exposure with melanin pigmentation among African American smokers. A criterion-based sample was employed to collect data from a study of 147 adult African American current smokers. Carbon monoxide, saliva cotinine samples, and skin reflectance measures were obtained from each participant. Questionnaire data on demographic, sociological and behavioral questions related to smoking and skin color were gathered. The three dependent measures were the average number of cigarettes per day (CPD), Fagerström Test of Nicotine Dependence (FTND) score, and cotinine concentration. Analysis of variance, Pearson Correlations, and Multiple Linear Regression were conducted to analyze findings. The mean constitutive melanin reading was 56.3 and 66.5 for facultative melanin. Respondents on average smoked 19 CPD, had a mean FTND of 5.6, and a cotinine concentration of 435 ng/ml. Facultative melanin level was correlated with CPD and cotinine concentration in the bivariate analysis. The multiple linear regression results revealed that facultative melanin was significantly and positively related to CPD, the FTND, and cotinine. The results of this analysis support the hypothesis of a positive association between melanin levels and tobacco use, dependence, and exposure among African American smokers. This analysis may have important implications for research and interventions on tobacco dependence and disease outcomes. Further research on melanin and nicotine among African Americans as well as other population groups is warranted.     

紫外线照射对浅表角质层细胞黑素的影响

为了了解紫外线照射对浅表角质层细胞黑素含量和分布的影响，用紫外线照射１２名健康志愿埂前内侧皮肤，分别于照射前后用粘附胶带取受试部位浅表角质层细胞。标本经Ｆｏｎｔａｎａ－Ｍａｓｓｏｎ银氨液处理后，用ＯｐｔｏｍａｘＶ型计算机成像分析系统测量和观察浅表角质层细胞中黑素含量和分布。结果，紫外线照射后１０ｍｉｎ，浅表角质层细胞中黑素含量与照和比较无明显差异；紫外线照射后１周，清表角质层细胞黑素含睛明显增加，     

复方木尼孜其颗粒对小鼠B16黑素瘤细胞酪氨酸酶活性及黑素合成的影响

目的 研究复方木尼孜其颗粒对小鼠B16黑素瘤细胞酪氨酸酶活性及黑素合成的影响.方法 培养小鼠B16黑素瘤细胞,采用MTT法测定不同浓度复方木尼孜其颗粒对细胞增殖的影响,采用L-DOPA氧化法测定其对细胞酪氨酸酶活性的影响,采用NaOH裂解法检测细胞黑素含量.结果 复方木尼孜其颗粒高剂量组能明显抑制小鼠B16黑素瘤细胞黑素的合成,但是对酪氨酸酶活性无影响.结论 复方木尼孜其颗粒能抑制小鼠B16黑素瘤细胞黑素的合成,在治疗色素性皮肤病中有一定前景.