Research progress on the treatment of gingival pigmentation / 口腔疾病防治

@#Gingival pigmentation is a nonplaque gum disease. Patients are often afraid to communicate with others because of gum color problems, which affect the social and mental health of patients. The commonly used treatment methods for gingival pigmentation include scalpel excision, gingival grinding, laser therapy, cryosurgery and electrosurgery. In this paper, the progress of gingival pigmentation treatment was reviewed in terms of bleeding, pain, tissue healing and recoloring. The results showed that the clinical effect of laser treatment was better. Among them, the semiconductor laser had more advantages in reducing bleeding, pain and the restaining rate, while the Er:Cr:YSSG/Er:YAG laser performed better for promoting tissue healing. Clinicians can choose the best kind of laser to use according to the actual situation. For patients with thin gingival biotypes, floating gingival transplantation or substitute materials can be selected to restore the gingival morphology. With the in-depth study of melanin regulation mechanisms, various drugs, such as ascorbic acid, natural peptides, synthetic peptides and derivatives, may be the main research direction for the treatment of gingival pigmentation in the future.

Ação da luz visível na oxidação da melanina e no descolorimento do cabelo / Action of the visible on the melanin oxidation and hair discoloration

O dano capilar causado pelo descolorimento oxidativo é muito intenso, sendo que dois fatores são responsáveis por essa ação: primeiro, a ação direta e danosa do oxidante em diversas estruturas capilares e segundo, o dano oxidativo primário facilita o dano causado por outros agentes físicos (luz, temperatura) e químicos (tensoativos), que comumente tem ação nos cabelos. Desenvolver conceitos e tecnologias que possam tornar o oxidante específico para a melanina e por conseguinte efetuando o descolorimento sem causar danos ao fio é extremamente desejável. Neste trabalho buscaremos entender de que forma a luz visível pode aumentar a ação do oxidante sem danificar o fio colateralmente. O objetivo principal deste trabalho é demonstrar que é possível utilizar a luz visível, que é absorvida pela melanina, para tornar esse pigmento mais suscetível ao agente oxidante e desta forma, permitir que o descolorimento seja realizado com concentrações pequenas de oxidante. Também almejamos desenvolver métodos de análises por microscopia ótica de fluorescência e de reflexão para mensurar o dano nas estruturas dos fios processados com oxidante e na presença ou ausência da luz

The capillary damage caused by oxidative discoloration is very intense, and two factors are responsible for this action: first, the direct and harmful action of the oxidant on several capillary structures and second, the primary oxidative damage facilitates the damage caused by other physical agents (light, temperature) and chemicals (surfactants), which commonly have action on the hair. Developing concepts and technologies that can make the oxidant specific to melanin and therefore discoloring without causing damage to the hair is extremely desirable. In this work we will try to understand how visible light can increase the oxidant's action without damaging the wire collaterally. The main objective of this work is to demonstrate that it is possible to use visible light, which is absorbed by melanin, to make this pigment more susceptible to the oxidizing agent and, thus, to allow the discoloration to be carried out with small concentrations of oxidizer. We also aim to develop methods of analysis by optical fluorescence and reflection microscopy to measure the damage to the structures of the threads processed with oxidizer and in the presence or absence of light

The Role of Eye Color in the Emergence of Tinnitus in Silence

Abstract Introduction Previous research suggests that African Americans are less likely than Caucasians to perceive tinnitus in sustained silence. Objective To evaluate the association between non-cutaneous melanin as indicated by eye color and the emergence of temporary tinnitus during a brief period of silence. Methods A cross-section of adults grouped according to their eye color were exposed to silence. A total of 62 adults, aged 18 to 35 years (10 males, 52 females) were required to sit in silence for 10 minutes, after which they filled out a questionnaire to report their eye color and any perception of sounds in the ears or head. Results In total, 63% of the participants perceived tinnitus while sitting in silence, and, of these 95% perceived the tinnitus sounds within 5 minutes of sitting in silence. Though African Americans were less likely to perceive tinnitus in silence, this difference was not significant (p = 0.6). After a period of silence, 69% of the subjects with light-colored eyes and 58% of the dark-eyed subjects perceived tinnitus. This difference was not statistically significant (χ2(1) = 0.77; p = 0.38). Conclusion When exposed to reduced auditory stimulation, 3 out of 5 normal-hearing people are likely to experience tinnitus. However, there was no relationship between eye color and the perception of tinnitus in silence. Although melanin has been shown to play a role in the protection of the ear against noise trauma and the effects of age-related hearing loss, its role in the emergence of tinnitus needs further investigation.

AMELANOTIC MELANOMA- RARE CASE REPORT

Amelanotic melanoma is an uncommon type of of melanoma which lacks melanin pigment (1). Of all the melanoma cases, approximately 2- 8% cases represents amelanotic melanoma. The exact prevalence of this malignancy is more due to misdiagnosis. Due to lack of clinical criteria and pigmentation, the condition often detected late (2). Amelanotic melanomas are commonly found on the face, which shows microscopically the characteristics of desmoplasia (desmoplastic melanoma), but other body parts can also be involved (4)

Malignant Melanoma Infiltrating the Bone Marrow.

Malignant melanoma with infiltration into the bone marrow is seldom reported in the literature, for they are exceedingly rare. The primary site is not always apparent and a sizeable number of cases have been attributed to an occult primary. Metastasis to bone marrow is a terminal event usually occurring in stage IV of the disease and can be a focus of residual tumor cells which can cause a relapse.The current documentation is of a case of melanoma occurring as a rectal primary with anemia, thrombocytopenia, and leukoerythroblastic reaction. The marrow aspirates and trephine biopsy showed round to spindle-shaped malignant cells with intracytoplasmic brown-black coarse pigment, suggestive of melanin. The patient was diagnosed with stage IV melanoma but was lost for follow-up. The recognition of such an entity is important for both pathologists and clinicians alike. This case is being reported for the novelty of such an occurrence.

In vitro anti-melanoma effect of polyphenolic compounds

Objective: To evaluate the effects of phenolic acids (caffeic, ferulic, and coumaric acids) and flavones (luteolin and apigenin) on the proliferation and melanogenesis in murine melanoma B16-F10 cells. Methods: Cell proliferation was determined after 24 and 48 hours of incubation using MTT assay. The effects of these tested compounds on cell cycle progression were analyzed by flow cytometry. Moreover, the melanin content and tyrosinase activity were measured spectrophotometrically at 475 nm. Results: Luteolin and apigenin exhibited significant anti-proliferative activity against B16-F10 cells, while caffeic, ferulic, and coumaric acids induced slight inhibition after 24 and 48 hours of incubation. The tested compounds disturbed cell cycle progression of B16-F10, by a subsequent decrease in G

Effects of nucleus accumbens GABA-lateral hypothalamic area MCH neural pathway on rewarding feeding / 中华行为医学与脑科学杂志

Objective:To explore the effects of the γ-aminobutyric acid(GABA) neurons and melanin-concentrating hormone (MCH) neurons of the nucleus accumbens (NAc)-lateral hypothalamic area (LHA) neural pathway on the rewarding feeding(palatable food sweat condensed milk) in the obesity rats.Methods:Total 142 male Wistar rats of SPF grade were divided into normal diet (ND) group ( n=68) and high-fat diet induced obesity (DIO) group ( n=74) according to the principle of body mass matching. The rats in the two groups were given normal diet and high-fat diet for 8 weeks. Eight weeks later, 6 DIO rats were randomly selected to observe the nerve projection from GABA neurons in NAc to MCH neurons in LHA by fluorogold retrograde tracing combined fluorescence immunohistochemistry. And the expressions of c-Fos and MCH in LHA after ingestion of sweet condensed milk(rewarding feeding) were observed by fluorescence immunohistochemistry (6 rats in each group). GABA receptor agonist Musimol or GABA receptor antagonist Bicuculine was microinjected into the nucleus of LHA to observe the effect of GABA on rewarding food intake in ND and DIO rats ( n=8 in each group), and the changes of rewarding food intake after blocking MCH signal ( n=8 in each group). SPSS 17.0 was used for statistical analysis, two-way ANOVA and post hoc Bonferroni test were used for comparison among multiple groups, and t-test was used for comparison between two groups. Results:After 8 weeks of high-fat diet modeling, the intake of delicious food in DIO rats was significantly higher than that in ND rats((12.52±2.29) mL, (7.45±1.23) mL, t=4.778, P<0.01) after satiety.The results of fluorogold retrograde tracing combined with fluorescence immunohistochemistry showed that GABA neurons in NAc projected nerve fibers to neurons in LHA, and GABA A receptors in some neurons in LHA coexisted with MCH.The results of NAc-LHA pathway on delicious food intake showed that the interaction between rat group and drug intervention was significant( F=9.869, P<0.01). Simple effect analysis showed that the intake of delicious food after microinjection of Musimol into LHA nucleus of ND rats was significantly lower than that of microinjection normal saline ((4.25±1.38) mL, (7.29±1.49) mL, P<0.01), while the intake of delicious food after injection of Bicuculine was significantly higher than that of microinjection normal saline((10.72±2.11) mL, (7.29±1.49) mL, P<0.05). The intake of delicious food after microinjection of Musimol into LHA nucleus in DIO group was significantly lower than that of microinjection normal saline((3.51±1.77)mL, (13.68±2.95) mL, P<0.01), but there was no significant difference between microinjection Bicuculine and microinjection normal saline ((14.83±3.44) mL, (13.68±2.95) mL, P>0.05). The results of blocking MCH signal on delicious food intake showed that the interaction effect between SNAP-94847 and Bicuculine intervention was not significant ( F=1.468, P>0.05). The main effect of SNAP-94847 intervention was significant ( F=15.880, P<0.01)and the main effect of Bicuculine intervention was significant ( F=6.930, P<0.05). After intracerebroventricular injection of MCH receptor blocker SNAP-94847, the delicious food intake of ND rats was significantly less than that of injection normal saline((4.78±1.72) mL, (7.63±2.77) mL, P<0.05), and it was not affected by pre injection of Bicuculine in LHA ((6.24±2.18) mL, (4.78±1.72) mL, P>0.05). In the DIO rats, the interaction effect between SNAP-94847 and Bicuculine intervention was not significant( F=0.006, P>0.05). The main effect of SNAP-94847 intervention was significant ( F=18.46, P<0.01) and the main effect of Bicuculine intervention was not significant ( F=2.059, P>0.05). After intracerebroventricular injection of MCH receptor blocker SNAP-94847, the delicious food intake of DIO rats was significantly lower than that of injection normal saline((6.89±2.11) mL, (12.19±4.36) mL, P<0.05), and it was not affected by pre injection of Bicuculine in LHA ((8.72±2.26) mL, (6.89±2.11) mL, P>0.05). Conclusion:GABAergic signal in NAc can regulate the expression of MCH in neurons of LHA. In the DIO rats, the sensitivity of MCH neurons in LHA to satiety signal decreases and the hedonic feeding increases.

n-butanol part from Qubai tablet and study on its pharmacodynamics to de melanocyte model / 中国药房

OBJECTIVE To stud y the chemical cons tituents of n-butanol part of Qubai tablet and its pharmacodynamic effect on the model of de melanocyte. METHODS The n-butanol part of Qubai tablet was prepared. The chemical constituents were analyzed by ultra-high performance liquid chromatography-mass spectrometry （UPLC-MS）. Taking mice B 16 melanoma cells as the research object ，the de melanocyte model was established and divided into model group ，positive control different concentration groups（8-methoxypsoralen 10，50，100，150，200 μmol/L），solvent group （diluted with DMSO ）and Qubai tablet n-butanol part different concentration groups （10，50，100，150，200 μmol/L）. The number of cells were observed by inverted microscope ，and the cell proliferation rate ，the rate of melanin production and promotion rate of tyrosinase activity were also detected. RESULTS In the positive and negative ion mode ，53 compounds in the n-butanol part of Qubai tablet were preliminarily determined （29 in the positive ion mode ，33 in the negative ion mode ，overlapping 9），of which coumarins accounted for the largest proportion ， followed by flavonoids. The n-butanol part of Qubai tablet could significantly increase the number of cells ，which was positively correlated with the action time and administration concentration. It could significantly increase the proliferation rate of cells ，the rate of melanin production and promotion rate of tyrosinase activity （P＜0.01）. CONCLUSIONS Coumarins and flavonoids may be the material basis for the anti-vitiligo effect of n-butanol part from Qubai tablet ；anti-vitiligo effect of n-butanol part of Qubai tablet may be realized by promoting tyrosinase activity.

Research progress on diagnosis and treatment of gingival pigmentation / 口腔疾病防治

@#Gingival pigmentation(GP) manifests as dark pigmentation spots, such as black or brown spots, in the gums. It is mostly caused by the deposition of melanin particles secreted by melanocytes on the gingival epithelium. The influencing factors may be divided into two categories, exogenous and endogenous. Exogenous factors include heavy metals, tattoos, smoking or drug use, and endogenous factors are related to certain diseases. The clinical grading of GP helps make a reasonable assessment of the necessity of treatment and prognosis. The Dummett-Gupta oral pigmentation index is a commonly used grading method, and the new grading method formed by combining the etiology and clinical manifestations described the patient’s situation more comprehensively. It is necessary to ask for a detailed medical history, complete examination, and correctly differentiate between physiological GP and GP caused by pathological state. Laser treatment is the currenttreatment with a better treatment effect and higher patient acceptance, and it is more comfortable and convenient, including diode laser, Er: YAG laser, and Nd: YAG laser, etc. This article summarizes the formation factors, clinical manifestations and treatment methods of GP to provide ideas for the clinical diagnosis and treatment of GP.

Physicochemical properties, molecular structure, antioxidant activity, and biological function of extracellular melanin from Ascosphaera apis / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Ascosphaera apis spores containing a dark-colored pigment infect honeybee larvae, resulting in a large-scale collapse of the bee colony due to chalkbrood disease. However, little is known about the pigment or whether it plays a role in bee infection caused by A. apis. In this study, the pigment was isolated by alkali extraction, acid hydrolysis, and repeated precipitation. Ultraviolet (UV) analysis revealed that the pigment had a color value of 273, a maximum absorption peak at 195 nm, and a high alkaline solubility (7.67%) and acid precipitability. Further chemical structure analysis of the pigment, including elemental composition, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, mass spectrometry, and nuclear magnetic resonance (NMR), proved that it was a eumelanin with a typical indole structure. The molecular formula of melanin is C10H6O4N2, and its molecular weight is 409 Da. Melanin has hydroxyl, carboxyl, amino, and phenolic groups that can potentially chelate to metal ions. Antioxidant function analyses showed that A. apis melanin had a high scavenging activity against superoxide, hydroxyl, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, and a high reducing ability to Fe3+. Indirect immunofluorescence assay (IFA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses showed that A. apis melanin was located on the spore wall. The spore wall localization, antioxidant activity, and metal ion chelating properties of fungal melanin have been suggested to contribute to spore pathogenicity. However, further infection experiments showed that melanin-deficient spores did not reduce the mortality of bee larvae, indicating that melanin does not increase the virulence of A. apis spores. This study is the first report on melanin produced by A. apis, providing an important background reference for further study on its role in A. apis.

Polimorfismos de nucleótido simple (PNSs) del gen MC1R en alpacas negras y marrones / Single nucleotide polymorphisms (SNPs) of the MC1R gene in black and brown alpacas

Resumen En alpacas los fenotipos del color de vellón tienen diferentes terminologías que induce a una confusión dentro del color marrón y sus tonalidades, el que requiere de una mejor descripción y cuantificación. En consecuencia los objetivos del estudio fueron cuantificar el color de fibra e identificar los PNSs informativos del gen MC1R (receptor 1 de melanocortina) en alpacas marrones y negras. Un fenotipo vicuña (n=14) y cuatro fenotipos de alpacas (n=79), marrón claro, marrón oscuro, marrón-negro y negro fueron evaluados por colorimetría. El vellón de vicuña mostró mayor luminosidad (47.74) e intensidad de color (24.33) respecto a las alpacas marrones. Los valores obtenidos de CIE L*a*b* (luminosidad e intensidad) sugieren valores bajos en alpacas eumelánicas y altos en alpacas feomelánicas. En vicuña y alpaca la secuencia codificante del gen MC1R tiene un solo exón de 954 pb, las vicuñas no mostraron la deleción (c.224_227del). Sin embargo, esta deleción se ha observado en los tres fenotipos de alpaca (marrón claro, marrón oscuro y negro), al igual que los cinco PNSs no sinónimos que ya fueron descritos en otras poblaciones, c.82A>G, c.259G>A, c.376G>A, c.587T>C, c.901C>T (p.T28A, p.M87V, p.G126S, p.F196S y p.R301C). Para las dos especies, se identificaron un total de ocho haplotipos definidos por los cinco PNSs. No se observaron asociaciones entre los fenotipos de color y los PNSs: c.259G>A, c.376G>A y c.901C>T (p>0.05), probablemente debido a la influencia de otros genes como el ASIP en la expresión del color. Nuestros resultados, así como los estudios previos evidenciaron regiones altamente conservadas en la secuencia codificante del gen MC1R.

Abstract In alpacas color fleece phenotypes have different terminologies that induces confusion within the brown color and its shades, it requires a better description and quantification. Consequently, the aims of the study were to quantify the color of fiber and identify the informational SNPs in the MC1R gene (melanocortin 1 receptor) in brown and black alpacas. A vicuña phenotype (n=14) and four alpaca phenotypes (n=79), light brown, dark brown, brown-black and black were evaluated by colorimetry. The vicuña fleece showed greater lightness (47.74) and color intensity (24.33) compared to brown alpacas. The CIE L*a*b* values (lightness and intensity) suggest low values in eumelanic alpacas and high in pheomelanic alpacas. In vicuña and alpaca, the coding sequence of the MC1R gene has a single exon of 954 bp, in vicuñas the deletion (c.224_227del) was not observed. However, this deletion was observed in three alpaca phenotypes (light brown, dark brown and black), as well as the five non-synonymous SNPs described in other populations, c.82A>G, c.259G>A, c.376G>A, c.587T>C, c.901C>T (p.T28A, p.M87V, p.G126S, p.F196S, and p.R301C). Eight haplotypes defined by the five SNPs were identified in both species. The associations between color phenotypes and SNPs were not observed (p>0.05), probably due to the influence of other genes such as ASIP on color expression. Our results as well as previous studies showed highly conserved regions in the coding sequence of the MC1R gene.

Melatonin inhibits UVB-induced melanin synthesis by regulating p53-mediated premature senescence in HaCaT cells / 中华放射医学与防护杂志

Objective:To explore the mechanism and regulatory effects of melatonin on UVB-induced melanin synthesis in human immortalized keratinocytes (HaCaT), so as to provide a theoretical basis for the skin protection of melatonin.Methods:HaCaT cells were pretreated with 10 -5 mol/L melatonin and then irradiated with 80 mJ/cm 2UVB. The melanin content was detected by NaOH assay, the proportion of premature senescence cells was detected by β-galactosidase staining kit, and the protein expression levels of both p53 and tyrosinase (TYR) were detected by Western blot at 72 h after UVB exposure. After 12 h pretreatment of ATM/ATR inhibitor, p53 inhibitor and melatonin, the proportion of premature senescence and the change of melanin content in HaCaT cells were detected at 72 h after 80 mJ/cm 2 UVB irradiation. Results:Melatonin inhibited UVB-induced increases of melanin content ( t=56.65, 13.39, P<0.05) and TYR expression ( t=16.46, P<0.05) in HaCaT cells. Melatonin alleviated UVB-induced premature senescence ( t=7.139, P<0.05) and inhibited UVB-induced increase of p53 expression ( t=19.08, P<0.05) in HaCaT cells. In addition, ATM/ATR inhibitor, p53 inhibitor and melatonin all inhibited UVB-induced increase of melanin content in HaCaT cells. Conclusions:Melatonin inhibits TYR-mediated melanin synthesis by regulating p53-related premature senescence in HaCaT cells after UVB irradiation.

Histological comparison of two special methods of staining melanin in human skin / Comparación histológica de dos métodos especiales de tinción de melanina en piel humana

SUMMARY: Human skin melanin was stained using the Fontana's silver nitrate method and Schmorl method. The results showed that, in the Fontana's silver nitrate method, melanin and silver-bound cells were black and other tissues were red. When stained using the Schmorl method, effects on melanin differed based on whether the nuclei were stained. When the nucleus was stained, melanin appeared blue-black or blue-green, and other tissue structures were purple. When the nucleus was not stained, melanin was orange and other structures were pink. Comparing the two staining methods, we concluded that Fontana's silver nitrate method takes a long time; in contrast, the Schmorl method showed two different types of results depending on whether the nucleus was stained, and it takes less time than Fontana staining, so we here consider the Schmorl method more suitable for special staining of melanin than Fontana's silver nitrate method.

RESUMEN: La melanina de la piel humana se tiñó utilizando el método del nitrato de plata de Fontana y el método Schmorl. Los resultados mostraron que, en el método del nitrato de plata de Fontana, la melanina y las células unidas a plata eran negras y otros tejidos eran rojos. Cuando se tiñó con el método de Schmorl, los efectos sobre la melanina difirieron en función de si se tiñeron los núcleos. Cuando se tiñó el núcleo, la melanina apareció de color azul-negro o azul-verde, y otras estructuras de tejido fueron de color púrpura. Cuando el núcleo no estaba teñido, la melanina era naranja y otras estructuras eran rosadas. Al comparar los dos métodos de tinción, llegamos a la conclusión de que el método del nitrato de plata de Fontana lleva mucho tiempo; por el contrario, el método Schmorl mostró dos tipos diferentes de resultados dependiendo de si el núcleo estaba teñido, y lleva menos tiempo que la tinción de Fontana, por lo que aquí consideramos que el método Schmorl es más adecuado para la tinción especial de melanina que el método del nitrato de plata de Fontana.

Melanocitoma meníngeo del ángulo pontocerebeloso: claves imagenológicas para su abordaje / Cerebellopontine meningeal melanocytoma: keys for imaging diagnostic approach

Resumen: Las lesiones del ángulo pontocerebeloso (APC) representan el 6 al 10% de las neoplasias intracraneales, siendo los schwannomas vestibulares y meningiomas los más comunes. Sin embargo, hasta el 15% pueden ser otras lesiones, entre ellas las derivadas a partir de restos de células melanocíticas presentes en las leptomeninges. El diagnóstico diferencial de las patologías tumorales del APC es extenso, siempre teniendo en cuenta las lesiones más comunes. Sin embargo, cuando las características radiológicas no son las esperadas, el enfoque debe orientarse hacia las lesiones inusuales, poniendo en contexto las diferentes estirpes celulares que pueden dar origen a las neoplasias en esta localización, como las neoplasias melanocíticas. Se presenta el caso de un masculino de 74 años con síndrome cerebeloso de tórpida evolución, al cual se le realiza RM de cerebro contrastada, identificando una lesión de base dural en el APC izquierdo, con hiperintensidad de señal en T1 e hipointensidad en T2, atípico para las lesiones más comunes en esta región, que sugiere su contenido melanocítico.

Abstract: Cerebellopontine angle tumors (CPA) represent approximately 6 to 10% of intracranial tumors. Vestibular Schwannomas and meningiomas are the most common, however up to 15% can be of other origin, including from melanocytes derived from the neural crest. The differential diagnosis of CPA pathologies is extensive, always taking into account the most common ones. However, if the radiological characteristics are not the expected, the approach should be directed towards unusual lesions, putting into context the different cell lines that can give rise to the neoplasm at this location, such as melanotic neoplasms. We present a case of a 74-year-old male, who presented with a cerebellar syndrome. Due to an atypical clinical evolution, a contrast enhanced head MRI was performed, revealing a dural based tumor on the left CPA, which was hyperintense on T1 and hypointense on T2 weighted sequences, which is not expected from the common lesions at this region and suggested it's melanotic content.

Oxyresveratrol inhibits cellular tyrosinase-related oxidative stress-induced melanogenesis in B16 melanoma cells

Cellular oxidative stress is caused by an imbalance in the redox status and manifests as hyperpigmentation disorders.Reactive oxygen species, particularly hydrogen peroxide (H2O2) as the highly reactive hydroxyl radicals, promotethe melanin production through the induction of tyrosinase enzyme activity. In this study, the antioxidant activity ofoxyresveratrol was investigated by 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. In addition, melanin biosynthesis, tyrosinase activity, and cellular oxidants due to thebioactive component, oxyresveratrol, were determined in B16 cells by melanin content assay, cellular tyrosinase activityassay, and the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay, respectively. Hydrogen peroxide induced themelanogenesis through tyrosinase activity-related cellular oxidants, whereas oxyresveratrol showed a potent antioxidantactivity by DPPH and ABTS assays. At the concentrations of 10 and 12.5 µg/ml, oxyresveratrol significantly inhibitedmelanogenesis in B16 melanoma cells and also suppressed tyrosinase activity and cellular oxidants. Effective doses ofoxyresveratrol inhibit melanogenesis through bioactivity of cellular tyrosinase-related oxidative stress

Regression of dark color in subterranean fishes involves multiple mechanisms: response to hormones and neurotransmitters

Organisms with source-populations restricted to the subterranean biotope (troglobites) are excellent models for comparative evolutionary studies, due to their specialization to permanent absence of light. Eye and dark pigment regression are characteristics of most troglobites. In spite of the advance in knowledge on the mechanisms behind eye regression in cave fishes, very little is known about pigmentation changes. Studies were focused on three species of the genus Pimelodella. Exemplars of the troglobitic P. spelaea and P. kronei were compared with the epigean (surface) P. transitoria, putative sister-species of the latter. Melanophore areas and densities are significantly lower in the troglobitic species. Evaluating the in vitro response of these cells to adrenaline, acetylcholine and MCH, we observed a reduced response in both troglobites to adrenaline. The same trend was observed with MCH, but not statistically significant. No response to acetilcholine was detected in all the three. Contrary to expectations, even though eye-regression in P. spelaea was much lower than in P. kronei, pigmentation regression was more advanced. Multiple mechanisms of loss showing a mosaic of traits in troglobitic fishes are discussed here.(AU)

Organismos com populações-fonte restritas ao biótopo subterrâneo (troglóbios) são excelentes modelos para estudos evolutivos comparativos, devido à especialização resultante do isolamento sob um regime seletivo particular, com ênfase na permanente falta de luz. A regressão do olho e da pigmentação são características dos troglobites. Apesar do avanço do conhecimento sobre os mecanismos subjacentes à regressão ocular em peixes de caverna, pouco se sabe sobre mudanças de pigmentação. Os estudos foram focados em três espécies do gênero Pimelodella. Exemplares das espécies troglóbias P. spelaea e P. kronei foram comparados com a epígea P. transitoria, provável espécie-irmã dessa última. As áreas e densidades dos melanóforos são significativamente menores nas espécies troglóbias. Avaliando a resposta in vitro dessas células à adrenalina, acetilcolina e MCH, observamos uma resposta reduzida em ambos os troglóbios à adrenalina. A mesma tendência foi observado com o MCH, mas não estatisticamente. Nenhuma resposta à acetilcolina foi detectada três. Contrariamente às expectativas, embora a regressão ocular em P. spelaea seja bem menor do que em P. kronei, a regressão na pigmentação foi mais acentuada. Múltiplos mecanismos de regressão, mostrando um mosaico de características em peixes troglóbios, são discutidos aqui.(AU)

Prevalence of melanin pigmentation in a yemeni population and its relation to some risk factors / Prevalência de pigmentação da melanina em uma população iemenita e sua relação com fatores de risco

Objective: The present study aimed to explore the prevalence of melanin pigmentation in a sample of Yemeni population and its relation to some possible risk factors. Material and Methods: This crosssectional study was performed on 440 patients attending a private clinic. Printed questionnaires were introduced to the patients and a clinical examination was performed for each patient. The questionnaire included questions regarding demographic data, and questions regarding some common habits such as smoking, khat chewing and consuming of hot drinks. Melanin pigmentation was assessed regarding its presence, most affected areas and the numbers of affected quadrants. The data were managed and analyzed using SPSS software program. Descriptive statistics and inferential statistics were performed and the associations of melanin with risk factors were evaluated at P value < 0.05. Results: Four hundred and forty patients with mean age 29 ± 8.21 years were included in the study. Of them, 67.5% were fair-skinned, 26.8% were smokers, 48.2% were khat chewers and 33.6% were hot drinks consumers. The prevalence of melanin pigmentation was 62.7%, with class I represented 56.5% of cases. Males showed more prevalence (67.9%) of melanin pigmentation than females (57.7%) with no significant difference. Results also showed more prevalence of melanin pigmentation in patients > 25 years, and darkskinned patients. Regarding habits, smoking, khat chewing and hot drink consumption habits showed significant associations with melanin pigmentation. Whereas the association of khat chewing and hot drinks alone with melanin pigmentation showed no significant relationship with melanin pigmentation while, the merge effects of khat chewing and smoking habits together with melanin pigmentation showed significant relationship with melanin pigmentation. Conclusion: It can be concluded that Yemeni people had high prevalence of melanin pigmentation with more prevalence of CL I type. Males, patients > 25 years and dark-skinned patients showed more prevalence of melanin pigmentation. Smoking, khat chewing and hot drinks consuming habits had significant associations with melanin pigmentation.(AU)

Objetivo: O presente estudo teve como objetivo explorar a prevalência de pigmentação da melanina em uma amostra da população iemenita e sua relação com alguns possíveis fatores de risco. Material e Métodos: Trata-se de um estudo transversal com 440 pacientes atendidos em uma clínica particular. Cada paciente respondeu a um questionário impresso e passou por um exame clínico. O questionário incluía perguntas sobre dados demográficos e questões sobre alguns hábitos comuns, como fumar, mastigar khat e consumir bebidas quentes. A pigmentação da melanina foi avaliada quanto à presença, áreas mais afetadas e número de quadrantes afetados. Os dados foram gerenciados e analisados no programa SPSS. Foi realizada estatística descritiva e inferencial e as associações de melanina com fatores de risco foram avaliadas com valor de p 25 anos e pacientes de pele escura. Quanto aos hábitos, tabagismo, mascar khat e consumo de bebida quente apresentaram associação significativa com a pigmentação da melanina. Enquanto a associação de mascar khat e bebidas quentes isoladamente não mostrou relação significativa com a pigmentação de melanina, enquanto os efeitos da associação dos hábitos de mascar e fumar khat juntamente com pigmentação por melanina mostraram relação significativa com a pigmentação por melanina. Conclusão: Pode-se concluir que o povo iemenita apresentou alta prevalência de pigmentação por melanina, com maior prevalência do tipo CL I. Homens, pacientes> 25 anos e pacientes de pele escura apresentaram maior prevalência de pigmentação da melanina. O hábito de fumar, mascar khat e consumir bebidas quentes teve associações significativas com a pigmentação da melanina. (AU)

Catalysis-based specific detection and inhibition of tyrosinase and their application / 药物分析学报

Tyrosinase is an important enzyme in controlling the formation of melanin in melanosome, and plays a key role in the pigmentation of hair and skin. The abnormal expression or activation of tyrosinase is associated with several diseases such as albinism, vitiligo, melanoma and Parkinson disease. Excessive deposition of melanin could cause diseases such as freckles and brown spots in the human body, and it is also closely related to browning of fruits and vegetables and insect molting. Detecting and inhibiting the activity of tyrosinase is of extraordinary value in the progress of diagnosis and treatment of these dis-eases. Therefore, many selective optical detection probes and small molecular inhibitors have been developed, and have made significant contributions to the basic and clinical research on these diseases. In this paper, the detection and inhibition of tyrosinase and their application in whitening products are reviewed, with special emphasis on development of fluorescent probes and inhibitors. Hopefully, this review will help design more efficient and sensitive tyrosinase probes and inhibitors, as well as shed light on novel treatment of diseases such as melanoma.

Photothermal Effect-based Cytotoxic Ability of Melanin from Shells to Heal Wounds Infected with Drug-resistant Bacteria / 生物医学与环境科学（英文）

Objective@#Owing to antibiotic abuse and the subsequent development of antibiotic resistance, bacterial infection has become one of the most persistent unresolved problems. New antibacterial agents, especially those that are environmental-friendly, are urgently needed.@*Methods@#Melanin extracted by filtration centrifugation and acid and proteolytic hydrolysis was characterized using UV, FTIR, TEM, and XPS. Photothermal conversion was calculated, and the bacteriostatic effects, and , were assessed by plate counting and ratios (%) of wound areas.@*Results@#Natural melanin hydrolyzed by trypsin had good photothermal conversion effects, which resulted in superior bacteriostatic activities. The extracted melanin along with laser NIR irradiation at 808 nm promoted the healing of wounds infected by drug-resistant bacteria and was biocompatible according to toxicity tests and .@*Conclusion@#The present findings indicated a safe and efficient method of developing natural antibacterial agents.

Melanin synthesis and regulation in vivo and commonly used melanin inhibitors from natural products and traditional Chinese medicine / 中国中药杂志

Melanin is an important factor affecting human skin color. This study defines its synthetic pathways and regulatory pathways have the practical significance for the treatment of diseases caused by pigmentation problems, such as chloasma. Besides, it also provides a theoretical basis for screening out melanin inhibitors and developing whitening and freckle products. At present, the melanin inhibitors used in whitening and freckle products mainly come from natural products and traditional Chinese medicine. This article first introduces the melanin biosynthesis pathway with tyrosinase as the core, defines the synthesis, transport and catalytic activity of tyrosinase as the three key factors affecting melanin synthesis, and then reviews two common types of melanin inhibitors, namely tyrosinase synthesis inhibitors and tyrosinase inhibitors derived from natural products and traditional Chinese medicine. This article provides guidance for the development of new melanin inhibitors, and puts forward the idea for combining and synergizing inhibitors according to different mechanisms, in order to develop new whitening formulas.