ABSTRACT
Fucoidan, a fucose-rich sulfated polysaccharide derived from brown seaweed in the class Phaeophyceae, has been widely studied for its possible health benefits. However, the potential of fucoidan as a possible treatment for hyperpigmentation is not fully understood. This study investigated the effects of fucoidan on melanogenesis and related signaling pathways using Mel-Ab cells. Fucoidan significantly decreased melanin content. While fucoidan treatment decreased tyrosinase activity, it did not do so directly. Western blot analysis indicated that fucoidan downregulated microphthalmia-associated transcription factor and reduced tyrosinase protein expression. Further investigation showed that fucoidan activated the extracellular signal-regulated kinase (ERK) pathway, suggesting a possible mechanism for the inhibition of melanin synthesis. Treatment with PD98059, a specific ERK inhibitor, resulted in the recovery of melanin production. Taken together, these findings suggest that fucoidan inhibits melanogenesis via ERK phosphorylation.
Subject(s)
Blotting, Western , Hyperpigmentation , Insurance Benefits , Melanins , Microphthalmia-Associated Transcription Factor , Monophenol Monooxygenase , Phaeophyceae , Phosphorylation , Phosphotransferases , SeaweedABSTRACT
The purpose of this study is to characterize the effects of KHG26792 (3-(naphthalen-2-yl(propoxy) methyl)azetidine hydrochloride), a potential skin whitening agent, on melanin synthesis and identify the underlying mechanism of action. Our data showed that KHG26792 significantly reduced melanin synthesis in a dose-dependent manner. Additionally, KHG26792 downregulated microphthalmia-associated transcription factor (MITF) and tyrosinase, the rate-limiting enzyme in melanogenesis, although tyrosinase was not inhibited directly. KHG26792 activated extracellular signal-regulated kinase (ERK), whereas an ERK pathway inhibitor, PD98059, rescued KHG26792-induced hypopigmentation. These results suggest that KHG26792 decreases melanin production via ERK activation. Moreover, the hypopigmentary effects of KHG26792 were confirmed in a pigmented skin equivalent model using Cervi cornus Colla (deer antler glue), in which the color of the pigmented artificial skin became lighter after treatment with KHG26792. In summary, our findings suggest that KHG26792 is a novel skin whitening agent.
Subject(s)
Animals , Antlers , Cornus , Hypopigmentation , MAP Kinase Signaling System , Melanins , Microphthalmia-Associated Transcription Factor , Monophenol Monooxygenase , Phosphotransferases , Skin Lightening Preparations , Skin , Skin, ArtificialABSTRACT
In this study we investigated the effects of fucoidan on the proliferation of fibroblasts and the reconstruction of a skin equivalent (SE). Fucoidan significantly stimulated the proliferation of CCD-25Sk human fibroblasts and Western blot analysis demonstrated that fucoidan markedly increased the expression of cyclin D1 and decreased the expression of p27. Fucoidan was used to reconstruct SE. Immunohistochemical staining showed that the addition of fucoidan to dermal equivalents increased expression of proliferating cell nuclear antigen (PCNA) and p63. In addition, expression of alpha6-integrin was significantly increased by fucoidan, whereas expression of beta1-integrin, type 1 collagen, elastin, fibronectin did not markedly change. These results suggest that fucoidan has positive effects on epidermal reconstruction and will therefore be beneficial in the reconstruction of SE.
Subject(s)
Humans , Blotting, Western , Collagen Type I , Cyclin D1 , Elastin , Fibroblasts , Fibronectins , Proliferating Cell Nuclear Antigen , SkinABSTRACT
This study investigated the effects of proline-serine (PS) and valine-serine (VS) dipeptides on melanogenesis in Mel-Ab cells. Proline-serine and VS significantly inhibited melanin synthesis in a concentration-dependent manner, though neither dipeptide directly inhibited tyrosinase activity in a cell-free system. Both PS and VS down-regulated the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase. In a follow-up study also described here, the effects of these dipeptides on melanogenesis-related signal transduction were quantified. Specifically, PS and VS induced ERK phosphorylation, though they had no effect on phosphorylation of the cAMP response element binding protein (CREB). These data suggest that PS and VS inhibit melanogenesis through ERK phosphorylation and subsequent down-regulation of MITF and tyrosinase. Properties of these dipeptides are compatible with application as skin-whitening agents.
Subject(s)
Cell-Free System , Cyclic AMP Response Element-Binding Protein , Dipeptides , Down-Regulation , Follow-Up Studies , Melanins , Microphthalmia-Associated Transcription Factor , Monophenol Monooxygenase , Phosphorylation , Signal TransductionABSTRACT
PURPOSE: To identify predictors of medical students' beliefs about intelligence among affective and cognitive factors, parental interest in children's education, and home economic status (HES). Of the 408 medical students who participated in this study, 398 completed and returned the questionnaires, yielding a total response rate of 97.5%. METHODS: Measures of students' beliefs about intelligence, intrinsic value, self-efficacy, test anxiety, cognitive strategies, self-regulation, parental interest in children's education, and HES were obtained. RESULTS: Spearman's correlations indicated that an entity theory of intelligence was negatively related to intrinsic value, self-efficacy, cognitive strategies, self-regulation, parental interest in children's education, and HES, and positively related to test anxiety. An incremental theory of intelligence was positively related to intrinsic value, self-efficacy, cognitive strategies, self-regulation, parental interest in children's education, and HES, and negatively related to test anxiety. Findings of independent t-tests showed that incremental theorists showed higher intrinsic value, self-efficacy, cognitive strategies, self-regulation, parental interest in children's education, and lower test anxiety than entity theorists. A binary logistic regression analysis showed that 72.9% of the medical students in the study were accurately classified as either incremental theorists or entity theorists with respect to intrinsic value, self-efficacy, test anxiety, and cognitive strategies. CONCLUSION: Medical educators need to be aware that medical students who have incremental beliefs about intelligence have higher intrinsic value, self-efficacy, cognitive strategies, and lower test anxiety than those who have fixed beliefs about intelligence. Perhaps a training program needs to be developed to enhance medical students' conceptions of intelligence based on the findings.
Subject(s)
Humans , Anxiety , Fertilization , Intelligence , Logistic Models , Parents , Self Efficacy , Students, Medical , Test Anxiety Scale , Surveys and QuestionnairesABSTRACT
PURPOSE: This study was to examine whether medical students' academic motivation, general academic stress influence their perceived academic performance. METHODS: Of the 606 medical students surveyed from two universities in Seoul and Incheon, 308 completed and returned the questionnaires yielding a total response rate of 50.8%. The final sample consisted of 129 premedical students (41.9%) and 179 medical students (58.1%). Of these, 189 were male (61.4%), 94 were female (30.5%), and 25 did not identify their gender (8.1%). Their average age was 22.43 years. Measures of students' academic motivation, general academic stress, medical stress, and their perceptions of academic performance were obtained. RESULTS: Pearson's correlations indicated that students' perceptions of academic performance were associated with academic motivation, general academic stress, and medical stress. It was observed that there were gender differences in 'perceptions of academic performance,' 'intrinsic academic motivation,' and 'extrinsic academic motivation.' Females scored themselves higher in 'perceptions of academic performance,'and 'ntrinsic academic motivation,'but lower in 'xtrinsic academic motivation'than did the males. Moreover, premedical students had higher 'perceptions of academic performance' and 'extrinsic academic motivation' scores, but lower 'eneral academic stress'and 'edical stress'scores than medical students. Hierarchical multiple regression analyses showed that the 'motivation'subscale from the academic motivation measure and 'social-psychological' subscale from the general academic stress measure predicted the perceptions of academic performances of the medical students after controlling for gender and education level. CONCLUSION: Medical educators need to be aware that medical students' perceived stress and their academic motivation affects their academic performance which can have a tremendous impact on their quality of life and psychological well-being. Perhaps an academic adjustment program needs to be developed to reduce students' perceived stress in medical training.
Subject(s)
Female , Humans , Male , Education , Motivation , Quality of Life , Seoul , Students, Medical , Students, Premedical , Surveys and QuestionnairesABSTRACT
We previously reported an identification of a 77-kDa GTP-binding protein that co-purified with the alpha 1-adrenoceptor following ternary complex formation. In the present paper, we report on the purification and characterization of this GTP-binding protein (termed G alpha h5) isolated from pig heart membranes. After solubilization of pig heart membranes with NaCl, G alpha h5 was purified by sequential chromatographies using DEAE-Cellulose, Q-Sepharose, and GTP-agarose columns. The protein displayed high-affinity GTP gamma S binding which is Mg(2+)-dependent and saturable. The relative order of affinity of nucleotide binding by G alpha h5 was GTP > GDP > ITP >> ATP > or = adenyl-5'-yl imidodiphosphate, which was similar to that observed for other heterotrimeric G-proteins involved in receptor signaling. Moreover, the G alpha h5 demonstrated transglutaminase (TGase) activity that was blocked either by EGTA or GTP gamma S. In support of these observations, the G alpha h5 was recognized by a specific antibody to G alpha h7 or TGase II, indicating a homology with G alpha h (TGase II) family. These results demonstrate that 77-kDa G alpha h5 from pig heart is an alpha 1-adrenoceptor-coupled G alpha h (TGase II) family which has species-specificity in molecular mass.
Subject(s)
Animals , Binding Sites , Binding, Competitive , Cross Reactions , GTP-Binding Proteins/metabolism , GTP-Binding Proteins/isolation & purification , GTP-Binding Proteins/immunology , Guanosine 5'-O-(3-Thiotriphosphate)/metabolism , Molecular Weight , Myocardium/chemistry , Transglutaminases/metabolism , Receptors, Adrenergic, alpha-1/metabolism , SwineABSTRACT
To assess the change of nitric oxide(NO) concentration according to photorefractive keratectomy(PRK) depth and the role of NO in cataractohenesis after excimer laser PRK. The treated 36 rabbits were divided into 12 groups according to PRK depth(-3.0, -7.0, -11.0 diopter [0]), the dates of sampling(the 1st day and the 7th day after PRK), and reatment of NOS inhibitor (NG-nitro-L-arginine methylester, L-NAME). NO concentration and superoxide dismutase(SOD) activity in the aqueous humor and malondialdehyde(MDA) concentration in the lens were measured. Changes of lens epithelium were examined by eletron microscopy on the 3rd day and the 6th day after -11.0D of PRK. The NO and MDA concentration in the group without L-NAME treatment on the 1st day after -11.0D of PRK were significantly higher than those in the L-NAME treated group and control group. The activity of SOD increased in all of the PRK treated group on the 1st day and was even higher on the 7th day. The histopathological changes of lens epithelium on the 3rd day after PRK were compatible with cellular necrosis and those of the 6th day after PRK were compatible with cellular reparing. The results suggested that the toxicity of NO after PRK correcting over -11.0D may a role in cataractogenesis, but the progress could be suppressed by treatment of NOS inhibitor.