Immersive virtual reality simulation training for cesarean section: a randomized controlled trial.

BACKGROUND: Caesarean section (CS) is a complex surgical procedure that involves many steps and requires careful precision. Virtual reality (VR) simulation has emerged as a promising tool for medical education and training, providing a realistic and immersive environment for learners to practice clinical skills and decision-making. This study aimed to evaluate the educational effectiveness of a VR simulation program in training the management of patients with premature rupture of membranes (PROM) and CS. MATERIALS AND METHODS: A two-arm parallel randomized controlled trial was conducted with 105 eligible participants randomly assigned to the VR group ( n =53) or the control group ( n =52) in a 1:1 ratio. The VR group received VR simulation training focused on PROM management and CS practice, while the control group watched a video presentation with narrative of clinical scenario and recording of CS. Both groups completed questionnaires assessing their prior experiences with VR, experience in managing patients with PROM and performing CS, as well as their confidence levels. These questionnaires were administered before and after the intervention, along with a mini-test quiz. RESULTS: Baseline characteristics and previous experiences were comparable between the two groups. After the intervention, the VR group had higher confidence scores in all four aspects, including managing patients with PROM, performing CS as an operator, and understanding the indications and complications of CS, compared to the control group. The VR group also achieved significantly higher scores on the mini-test quiz [median (interquartile range), 42 (37-48) in the VR group; 36 (32-40) in the control group, P <0.001]. CONCLUSION: VR simulation program can be an effective educational tool for improving participants' knowledge and confidence in managing patients with PROM and performing CS.

Peptide-N-glycosidase F or A treatment and procainamide-labeling for identification and quantification of N-glycans in two types of mammalian glycoproteins using UPLC and LC-MS/MS.

BACKGROUND: N-glycans in glycoproteins can affect physicochemical properties of proteins; however, some reported N-glycan structures are inconsistent depending on the type of glycoprotein or the preparation methods. OBJECTIVE: To obtain consistent results for qualitative and quantitative analyses of N-glycans, N-glycans obtained by different preparation methods were compared for two types of mammalian glycoproteins. METHODS: N-glycans are released by peptide-N-glycosidase F (PF) or A (PA) from two model mammalian glycoproteins, bovine fetuin (with three glycosylation sites) and human IgG (with a single glycosylation site), and labeled with a fluorescent tag [2-aminobenzamide (AB) or procainamide (ProA)]. The structure and quantity of each N-glycan were determined using UPLC and LC-MS/MS. RESULTS: The 21 N-glycans in fetuin and another 21 N-glycans in IgG by either PF-ProA or PA-ProA were identified using LC-MS/MS. The N-glycans in fetuin (8-13 N-glycans were previously reported) and in IgG (19 N-glycans were previously reported), which could not be identified by using the widely used PF-AB, were all identified by using PF-ProA or PA-ProA. The quantities (%) of the N-glycans (>0.1 %) relative to the total amount of N-glycans (100 %) obtained by AB- and ProA-labeling using LC-MS/MS had a similar tendency. However, the absolute quantities (pmol) of the N-glycans estimated using UPLC and LC-MS/MS were more efficiently determined with ProA-labeling than with AB-labeling. Thus, PF-ProA or PA-ProA allows for more effective identification and quantification of N-glycans than PF-AB in glycoprotein, particularly bovine fetuin. This study is the first comparative analysis for the identification and relative and absolute quantification of N-glycans in glycoproteins with PF-ProA and PA-ProA using UPLC and LC-MS/MS.

Novel strategy for dental caries by physiologic dentin regeneration with CPNE7 peptide.

OBJECTIVE: CPNE7-derived functional peptide (CPNE7-DP) has been introduced as a bioactive therapeutics for dentin diseases. CPNE7-DP regenerates tubular dentin on the pulpal side and occlude dentinal tubules. CPNE7-DP was capable to treat dentin hypersensitivity typically associated with dentinal wear at the neck of the tooth. However, the role of CPNE7-DP in another common dentin disease, dental caries, remains uninvestigated. In this study, we evaluated the potential application of CPNE7-DP in dentin caries using an experimental dentin caries model in rats. DESIGN: The stability of CPNE7-DP in caries-like environments including pathologic bacteria of caries or low pH was tested. We established a nutrition-time/hyposalivation-based dental caries rat model by inoculating caries-inducing bacteria and diet for sufficient time. Glycopyrrolate has been treated to induce reversible hyposalivation for accelerating caries progression. Then the tubular dentin regeneration was investigated with histologic methods. Also, modulation of inflammation or autophagy by CPNE7-DP was investigated with marker gene expression in human dental pulp cells (hDPCs) and immunohistochemistry. RESULTS: CPNE7-DP was stable with caries-inducing bacteria and low pH. Establishment of dentin caries was confirmed with radiographic and histologic evaluation. CPNE7-DP regenerated a substantial amount of tubular tertiary dentin and alleviated the pulp inflammation of dentin caries. Under inflammatory conditions, CPNE7-DP reduced the expression of inflammatory cytokines. These phenomena could be the consequence of the modulation of autophagy by CPNE7-DP, which reactivates inflamed odontoblasts. CONCLUSIONS: Overall, CPNE7-DP, which repairs caries through physiological dentin regeneration, might help overcoming the limitations of current restorative caries treatments.

Neuroprotective Effect of 1,3-dipalmitoyl-2-oleoylglycerol Derived from Rice Bran Oil against Cerebral Ischemia-Reperfusion Injury in Rats.

1,3-Dipalmitoyl-2-oleoylglycerol (POP) is a triacylglyceride found in oils from various natural sources, including palm kernels, sunflower seeds, and rice bran. In the current study, the neuroprotective effects and the specific mechanism of POP derived from rice bran oil were investigated for the first time using the middle cerebral artery occlusion/reperfusion (MCAO/R) model in rats. Orally administered POP at 1, 3, or 5 mg/kg (three times: 0.5 h before MCAO, after 1 h of MCAO, and after 1 h of reperfusion) markedly reduced the MCAO/R-induced infarct/edema volume and neurobehavioral deficits. Glutathione depletion and the oxidative degradation of lipids in the rat brain induced by MCAO/R were prevented by POP administration. The upregulation of phosphorylated p38 MAPKs, inflammatory factors (inducible nitric oxide synthase (i-NOS) and cyclooxygenase-2 (COX-2)), and pro-apoptotic proteins (B-cell lymphoma-2 (Bcl-2) associated X protein (Bax) and cleaved caspase-3) and the downregulation of the anti-apoptotic protein (Bcl-2) in the ischemic brain were significantly inhibited by POP administration. In addition, downregulation of phosphatidylinositol 3'-kinase (PI3K), phosphorylated protein kinase B (Akt), and phosphorylated cyclic (adenosine monophosphate) AMP responsive element-binding protein (CREB) expression in the ischemic brain was inhibited by POP administration. These results suggest that POP might exert neuroprotective effects by inhibition of p38 MAPK and activation of PI3K/Akt/CREB pathway, which is associated with anti-oxidant, anti-apoptotic, and anti-inflammatory action. From the above results, the present study provides evidence that POP might be effectively applied for the management of cerebral ischemia-related diseases.

Ilex latifolia Prevents Amyloid ß Protein (25-35)-Induced Memory Impairment by Inhibiting Apoptosis and Tau Phosphorylation in Mice.

Ilex latifolia Thunb. (Aquifoliaceae), a Chinese bitter tea called "kudingcha," has been widely consumed as a health beverage and found to possess antioxidant, antidiabetic, antihypertensive, anti-inflammatory, and anti-ischemic activities. The aim of the present study was to investigate the neuroprotective effects of an ethanol extract of I. latifolia against amyloid ß protein (Aß)-induced memory impairment in mice and neurotoxicity in cultured rat cortical neurons. Memory impairment in mice was induced by intracerebroventricular injection of 15 nmol Aß (25-35) and measured by the passive avoidance test and Morris water maze test. Chronic administration of I. latifolia (25-100 mg/kg, p.o.) significantly prevented Aß (25-35)-induced memory loss. I. latifolia also prevented the decrease of glutathione concentrations, increased lipid peroxidation, expression of phosphorylated tau (p-tau), and changes in apoptosis-associated proteins in the memory-impaired mouse brain. Exposure of cultured cortical neurons to 10 µM Aß (25-35) for 36 h induced neuronal apoptotic death. The neuronal cell death, elevation of intracellular Ca(2+) concentration, generation of reactive oxygen species, and expression of proapoptotic proteins caused by Aß (25-35) in the cultured neurons were inhibited by treatment with I. latifolia (1-50 µg/mL). These results suggest that I. latifolia may have a possible therapeutic role in managing cognitive impairment associated with Alzheimer's disease. The underlying mechanism might involve the antiapoptotic effects mediated by antioxidant activity and inhibition of p-tau formation.

A novel adenoviral vector-mediated mouse model of Charcot-Marie-Tooth type 2D (CMT2D).

Charcot-Marie-Tooth disease type 2D is a hereditary axonal and glycyl-tRNA synthetase (GARS)-associated neuropathy that is caused by a mutation in GARS. Here, we report a novel GARS-associated mouse neuropathy model using an adenoviral vector system that contains a neuronal-specific promoter. In this model, we found that wild-type GARS is distributed to peripheral axons, dorsal root ganglion (DRG) cell bodies, central axon terminals, and motor neuron cell bodies. In contrast, GARS containing a G240R mutation was localized in DRG and motor neuron cell bodies, but not axonal regions, in vivo. Thus, our data suggest that the disease-causing G240R mutation may result in a distribution defect of GARS in peripheral nerves in vivo. Furthermore, a distributional defect may be associated with axonal degradation in GARS-associated neuropathies.

Hexane extract from Polygonum multiflorum attenuates glutamate-induced apoptosis in primary cultured cortical neurons.

ETHNOPHARMACOLOGICAL RELEVANCE: Polygonum multiflorum has traditionally had wide use as an anti-aging treatment in East Asian countries. We investigated the neuroprotective effects of Polygonum multiflorum against glutamate-induced neurotoxicity with a focus on the anti-apoptotic mechanism in primary cultured cortical neurons. MATERIAL AND METHODS: Cell viability, cytotoxicity, morphological, flow cytometry, Western blot, and caspase activity assays were performed for examination of the neuroprotective effects of active hexane extract from Polygonum multiflorum (HEPM). RESULTS: Pretreatment with HEPM resulted in significantly decreased glutamate-induced neurotoxicity in a concentration-dependent manner and also resulted in drastically inhibited glutamate-induced apoptosis. Treatment with HEPM resulted in decreased expression of glutamate-induced death receptor (DR)4, and enhanced expression of glutamate-attenuated anti-apoptotic proteins, including Bcl-2, XIAP, and cIAP-1, and slightly reduced glutamate-induced cleavage of Bid. In addition, treatment with HEPM resulted in suppressed glutamate-induced activation of caspase-8, caspase-9, and caspase-3, and, subsequently, decreased degradation of poly(ADP-ribose) polymerase, ß-catenin, and phospholipase Cγ1 protein, which are downstream targets of activated caspase-3. CONCLUSIONS: The results of this study demonstrated that HEPM exerts a neuroprotective effect against glutamate-induced neurotoxicity via inhibition of apoptosis. This protection may be mediated through suppression of DR4 and up-regulation of Bcl-2, XIAP, and cIAP-1, as well as inhibition of caspase activation, resulting in prevention of apoptosis of cortical neurons.

Hexane extract from Uncaria sinensis exhibits anti-apoptotic properties against glutamate-induced neurotoxicity in primary cultured cortical neurons.

We explored the neuroprotective effects of a hexane extract from Uncaria sinensis (HEUS) against glutamate-induced toxicity focusing on its anti-apoptotic mechanism in primary cultured cortical neurons. Pretreatment with HEUS resulted in significantly reduced glutamate-induced toxicity in a dose-dependent manner with a decrease in the release of lactate dehydrogenase. Morphological assay and flow cytometry were performed for determination of the type of cell death; according to the results, treatment with HEUS resulted in a significant reduction of glutamate-induced apoptotic cell death. We examined the anti-apoptotic mechanism of HEUS; treatment with HEUS resulted in markedly decreased expression of death receptor (DR)4, which was induced by glutamate stimulation. In contrast, treatment with HEUS resulted in significantly enhanced levels of expression of glutamate-attenuated XIAP and Bcl-2, as well as marked blockade of glutamate-induced Bid cleavage, which inhibits both extrinsic and intrinsic apoptosis pathways. In addition, pretreatment with HEUS resulted in almost complete blockade of glutamate-induced activation of caspases-8, -9 and -3, as well as cleavage of poly (ADP-ribose) polymerase. These findings suggest that the neuroprotective effects of HEUS against glutamate-induced toxicity occur via inhibition of DR4 and expression of anti-apoptotic proteins XIAP and Bcl-2 resulting in effective abrogation of the activation of caspase cascades and promotion of cell survival.

Aqueous fraction from Cuscuta japonica seed suppresses melanin synthesis through inhibition of the p38 mitogen-activated protein kinase signaling pathway in B16F10 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Semen cuscutae has been used traditionally to treat pimples and alleviate freckles and melasma in Korea. The present study aimed to investigate the inhibitory effect of Cuscuta japonica Choisy seeds on alpha-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis. MATERIALS AND METHODS: The aqueous fraction from Semen cuscutae (AFSC) was used to determine anti-melanogenic effects by examination of cellular melanin contents, tyrosinase activity assay, cAMP assay and Western blot analysis for melanin synthesis-related signaling proteins in B16F10 mouse melanoma cells. RESULTS: AFSC markedly inhibited α-MSH-induced melanin synthesis and tyrosinase activity, and also decreased α-MSH-induced expression of microphthalmia-associated transcription factor (MITF) and tyrosinase-related proteins (TRPs). Moreover, AFSC significantly decreased the level of phosphorylated p38 mitogen-activated protein kinase (MAPK) signaling through the down-regulation of α-MSH-induced cAMP. Furthermore, we confirmed that the specific inhibitor of p38 MAPK (SB203580)-mediated suppressed melanin synthesis and tyrosinase activity was further attenuated by AFSC. AFSC also further decreased SB203580-mediated suppression of MITF and TRP expression. CONCLUSIONS: These results indicate that AFSC inhibits p38 MAPK phosphorylation with suppressed cAMP levels and subsequently down-regulate MITF and TRP expression, which results in a marked reduction of melanin synthesis and tyrosinase activity in α-MSH-stimulated B16F10 cells.

Electroacupuncture inhibits phosphorylation of spinal phosphatidylinositol 3-kinase/Akt in a carrageenan-induced inflammatory rat model.

We investigated the changes of pain-related spinal signaling pathway after electroacupuncture (EA) stimulation in a carrageenan-induced rat model. EA stimulation (2Hz, 1mA) was needle-delivered for 30 min at acupoints corresponding to Zusanli and Sanyinjiao 3 h after carrageenan injection. Thermal and mechanical sensitivity of the hindpaw induced by carrageenan was strongly inhibited by EA stimulation. Phosphorylation of extracellular signal-regulated kinase, phosphatidylinositol 3-kinase (PI3K), Akt, and cAMP response element-binding protein (CREB) were examined in the L4-5 segments of the spinal cord by Western blot analysis 4h and 5h after carrageenan injection. Phosphorylation of Akt and especially PI3K were significantly induced by carrageenan-induction, but these expressions were markedly inhibited by EA stimulation. CREB phosphorylation showed a similar, but insignificant, pattern as like PI3k/Akt. Immunohistochemical analyses confirmed that phosphorylation of PI3K and Akt showed a similar pattern as Western blotting and were observed in most neurons and a few astrocytes. EA and PI3K inhibitor synergistically inhibited carrageenan-induced hyperalgesia. These results reveal that both neuronal PI3K and Akt may play an important role in EA-induced antinociception via inactivation in an inflammatory pain model.

Partially purified components of Nardostachys chinensis suppress melanin synthesis through ERK and Akt signaling pathway with cAMP down-regulation in B16F10 cells.

UNLABELLED: Ethnopharmacological relevance Nardostachys chinensis has been used in folk medicine to treat melasma and lentigines in Korea. We investigated the inhibitory activities of Nardostachys chinensis in melanogenesis and its related signaling pathway. MATERIALS AND METHODS: Bioassay-guided fractionation of Nardostachys chinensis using solvent partitioning and purification with octadecylsilane open-column chromatography resulted in partial purification. The active 20% methanol chromatographic fraction from the ethyl acetate layer (PPNC) was used to investigate melanogenesis by melanin synthesis, tyrosinase activity assay, cAMP assay, Western blot and flow cytometric analyses in B16F10 mouse melanoma cells. RESULTS: PPNC markedly inhibits melanin synthesis and tyrosinase activity in a concentration-dependent manner. We also found that PPNC decreases microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1, and dopachrome tautomerase (Dct) protein expressions and MITF and tyrosinase mRNA levels. Moreover, PPNC reduces intracellular cAMP levels and activates mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI3K)/Akt expression in B16F10 cells. The specific MEK/ERK inhibitor PD98059 and PI3K/Akt inhibitor LY294002, block the PPNC-induced hypopigmentation effect, and abrogate the PPNC-suppressed expression of melanogenic proteins such as MITF, tyrosinase, TRP-1, and Dct. Using flow cytometry, we elucidated whether PPNC directly induces ERK phosphorylation at the level of an intact single cell. PPNC shows marked expression of phosphorylated ERK in live B16F10 cells and abrogates PPNC-induced phosphorylated ERK by PD98059 treatment. CONCLUSIONS: PPNC stimulates MEK/ERK phosphorylation and PI3K/Akt signaling with suppressing cAMP levels and subsequently stimulating MITF and TRPs down-regulation, resulting in melanin synthesis suppression.

Correlation of 18F-FDG uptake with apparent diffusion coefficient ratio measured on standard and high b value diffusion MRI in head and neck cancer.

UNLABELLED: Although the clinical applications of (18)F-FDG PET/CT and diffusion-weighted MRI (DWI) are similar to each other in head and neck cancer, the image acquisition methods in the 2 modalities are significantly different. (18)F-FDG PET/CT traces glucose metabolism, a nonspecific process essential for tumor growth. On the other hand, DWI provides information on Brownian motion of water molecules in tissues, which represents cellularity. The aim of our study was to investigate whether apparent diffusion coefficient (ADC) values at b = 1,000 (ADC(1,000)) and 2,000 (ADC(2,000)) s/mm(2) or whether the change (ADC(ratio)) of ADC values from b = 1,000 to 2,000 s/mm(2) has any significant correlation with the standardized uptake value (SUV) in patients with head and neck squamous cell carcinoma (HNSCC). METHODS: Our hospital's institutional review board approved this retrospective study. We included 47 patients (32 men and 15 women) with histopathologically proven HNSCC, who underwent both DWI (at both b = 1,000 s/mm(2) and b = 2,000 s/mm(2)) and (18)F-FDG PET/CT in the 2 wk before treatment. ADC(ratio) maps were generated using a pixel-by-pixel computation for which ADC(ratio) is (ADC(2,000)/ADC(1,000)) × 100. The mean ADC(1,000), ADC(2,000), and ADC(ratio) values were evaluated within a manually placed polygonal region of interest within the main tumor on every slice of the ADC(1,000), ADC(2,000), and ADC(ratio) maps, respectively. In addition, the maximal SUV (SUV(max)) and mean SUV (SUV(mean)) were measured for the entire tumor region of interest. Comparisons were made using Pearson correlation analysis, and partial correlation coefficients were derived. RESULTS: No significant correlation was found between the mean ADC(1,000) and SUV(mean) (r = -0.222, P = 0.1325) or the mean ADC(2,000) and SUV(mean) (r = -0.1214, P = 0.4163). However, the ADC(ratio) was significantly and positively correlated to both the SUV(mean) (r = 0.667, P < 0.001) and SUV(max) (r = 0.5855, P < 0.001). CONCLUSION: The ADC(ratio) and SUV were significantly correlated with each other in primary HNSCC patients, possibly because of a higher-cellularity region as a result of relatively increased tumor proliferation. Further studies are warranted to investigate the possible complementary role of DWI and PET/CT in various clinical settings, including staging and treatment response.

Combined effects of surface morphology and mechanical straining magnitudes on the differentiation of mesenchymal stem cells without using biochemical reagents.

Existing studies examining the control of mesenchymal stem cell (MSC) differentiation into desired cell types have used a variety of biochemical reagents such as growth factors despite possible side effects. Recently, the roles of biomimetic microphysical environments have drawn much attention in this field. We studied MSC differentiation and changes in gene expression in relation to osteoblast-like cell and smooth muscle-like cell type resulting from various microphysical environments, including differing magnitudes of tensile strain and substrate geometries for 8 days. In addition, we also investigated the residual effects of those selected microphysical environment factors on the differentiation by ceasing those factors for 3 days. The results of this study showed the effects of the strain magnitudes and surface geometries. However, the genes which are related to the same cell type showed different responses depending on the changes in strain magnitude and surface geometry. Also, different responses were observed three days after the straining was stopped. These data confirm that controlling microenvironments so that they mimic those in vivo contributes to the differentiation of MSCs into specific cell types. And duration of straining engagement was also found to play important roles along with surface geometry.

Inhibitory effects of 1-O-methyl-fructofuranose from Schisandra chinensis fruit on melanogenesis in B16F0 melanoma cells.

AIM OF THE STUDY: 1-O-methyl-fructofuranose (1-O-MFF) from the fruit of Schisandra chinensis is a traditional Korean medicinal herb that has a variety of beneficial properties. The effect of purified 1-O-MFF on melanogenesis including the activation of related signaling pathways was investigated. MATERIALS AND METHODS: The inhibitory activities of 1-O-MFF were examined by melanin synthesis, tyrosinase activity assay, Western blot and flow cytometric analyses in B16F0 mouse melanoma cells. RESULTS: 1-O-MFF significantly inhibited both melanin synthesis and tyrosinase activity in a concentration-dependent manner, and reduced the expression of melanogenic proteins including microphthalmia-associated transcription factor (MITF), tyrosinase and tyrosinase-related protein-1. 1-O-MFF phosphorylated and activated melanogenesis inhibitory proteins such as mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) and Akt. Flow cytometry confirmed that 1-O-MFF phosphorylated ERK and Akt proteins and recovered partially phosphorylated forms in cells treated with the MEK/ERK inhibitor compound PD98059 and the phosphatidylinositol 3-kinase (PI3K)/Akt inhibitor compound LY294002. CONCLUSIONS: The suppressive effects of 1-O-MFF on melanogenesis may involve down-regulation of MITF and its downstream signal pathway via the activation of MEK/ERK or PI3K/Akt.

Curcumin suppresses alpha-melanocyte stimulating hormone-stimulated melanogenesis in B16F10 cells.

The present study was designed to assess the potential inhibitory activity of curcumin on the alpha-melanocyte stimulating hormone (alpha-MSH)-stimulated melanogenesis signal pathway in B16F10 melanoma cells. The molecular mechanism of curcumin-induced inhibitory activity on the alpha-MSH-stimulated melanogenesis signal pathway, including expression of melanogenesis-related proteins and activation of melanogenesis-regulating proteins, was examined in B16F10 cells. Curcumin suppressed the cellular melanin contents and the tyrosinase activity in alpha-MSH-stimulated B16F10 cells. In addition, the expression of melanogenesis-related proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein 1 and 2 was suppressed by curcumin in the alpha-MSH-stimulated B16F10 cells. Notably, a melanogenesis-regulating signal such as mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) or phosphatidylinositol 3-kinase (PI3K)/Akt was activated by curcumin in the B16F10 cells treated with or without alpha-MSH. The suppressive activity of curcumin on alpha-MSH-induced melanogenesis was down-regulated by PD98059 and by LY294002. Our results suggest that the suppressive activity of curcumin on alpha-MSH-stimulated melanogenesis may involve the down-regulation of MITF and its downstream signal pathway through the activation of MEK/ERK or PI3K/Akt.

Partially purified Asiasari radix inhibits melanogenesis through extracellular signal-regulated kinase signaling in B16F10 cells.

The active fraction of the extract of Asiasari radix, the 60% methanol chromatographic fraction from the ethyl acetate layer (PPAR), was used to investigate the melanogenesis signal pathway in B16F10 melanoma cells. PPAR led to significantly decreased melanin synthesis and tyrosinase activity in a dose-dependent manner. PPAR also reduced the expression of melanogenesis-related proteins including microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein (TRP)s while down-regulating the expression of mRNA of MITF and tyrosinase. Melanogenesis-regulating signals, such as mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K)/Akt and p38 mitogen-activated protein kinase (MAPK) were evaluated, and ERK was activated by PPAR. The selective inhibitor of MEK/ERK, PD98059, abrogated all suppressive activities of PPAR on melanin biosynthesis, tyrosinase activation and expression of melanogenesis-related proteins. These results suggest that ERK activation by PPAR contributes to reduced melanin synthesis via ERK signal pathway-mediated suppression of MITF and its downstream signal pathway.

Partially purified Curcuma longa inhibits alpha-melanocyte-stimulating hormone-stimulated melanogenesis through extracellular signal-regulated kinase or Akt activation-mediated signalling in B16F10 cells.

Bioassay-guided fractionation of Curcuma longa by solvent partitioning and purification with octadecylsilane open column chromatography yielded a partial purification. The active 80% methanol chromatographic fraction from the ethyl acetate layer [partial purification from C. longa (PPC)] was used to investigate the alpha-melanocyte-stimulating hormone (alpha-MSH)-stimulated melanogenesis signal pathway in B16F10 cells. In cells stimulated alpha-MSH, PPC inhibited cellular melanin contents, tyrosinase activity and expression of melanogenesis-related proteins including microphthalmia-associated transcription factor (MITF), tyrosinase and tyrosinase-related proteins (TRP). Melanogenesis-regulating signalling such as mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI3K)/Akt was activated by PPC in alpha-MSH-stimulated B16F10 cells. The suppressive activity of PPC on alpha-MSH-induced melanogenesis was abrogated by selective inhibition of MEK/ERK (PD98059) and PI3K (LY294002). MEK/ERK or Akt activation by PPC may contribute to reduced melanin synthesis via MITF and its downstream signal pathway including tyrosinase and TRPs in alpha-MSH-induced melanogenesis.

Dichloromethane fraction of Cimicifuga heracleifolia decreases the level of melanin synthesis by activating the ERK or AKT signaling pathway in B16F10 cells.

Cimicifuga rhizoma has long been used in traditional Korean medicine. In particular, a Cimicifuga heracleifolia extract (CHE) was reported to inhibit the formation of glutamate and the glutamate dehydrogenase activity in cultured rat islet. Glutamate activates melanogenesis by activating tyrosinase. Accordingly, it was hypothesized that a CHE might inhibit the melanogenesis-related signal pathways including the inhibition of microphthalmia-associated transcription factor (MITF)-tyrosinase signaling and/or the activation of extracellular signal-regulated kinase (ERK)-Akt signaling. The results showed that CHE inhibits the cellular melanin contents, tyrosinase activity and expression of melanogenesis-related proteins including MITF, tyrosinase and tyrosinase-related protein (TRP)s in alpha-melanocyte-stimulating hormone-stimulated B16 cells. Moreover, CHE phosphorylates MEK, ERK1/2 and Akt, which are melanogenesis inhibitory proteins. The data suggest that CHE inhibits melanogenesis signaling by both inhibiting the tyrosinase directly and activating the MEK-ERK or Akt signal pathways-mediated suppression of MITF and its downstream signal pathway, including tyrosinase and TRPs. Therefore, C. heracleifolia would be a useful therapeutic agent for treating hyperpigmentation and an effective component in whitening and/or lightening cosmetics.

Loss of mitochondrial membrane potential and caspase activation enhance apoptosis in irradiated K562 cells treated with herbimycin A.

PURPOSE: We previously reported that herbimycin A (HMA) alters the mode of cell death of K562 cells induced by radiation and enhanced their radiosensitivity. In the present study, we explored the apoptosis-inducing activity of HMA and the fundamental mechanism via which it regulates radiation-induced cell death. MATERIALS AND METHODS: Chronic myelogenous leukemia (CML) cell line K562 was used. For X-irradiation and drug treatment, cells were plated at approximately 2x10(5) cells/ml. Exponentially growing cells were treated with 10 Gy of X-ray using a 6-MeV X-ray machine at a dose rate of 200-300 cGy/min. The cells were treated with 0.25 microM HMA immediately after irradiation and HMA remained for the entire culture period. The modes of cell death were discriminated by morphological changes, analysis of cell cycle, analysis of the mitochondrial events, and the expression of apoptosis-related proteins. RESULTS: Our data demonstrates that radiation induced a significant time-dependent increase of cell death and failed to sustain a prolonged G2 arrest in K562 cells. Radiation-induced cell death caused the accumulation of cyclinB1 and weak nuclear fragmentation, suggesting a mitotic catastrophe. This mitotic catastrophe was dependent upon the mitochondrial permeability transition pore (PTP) opening and was independent of caspase-3. In contrast, K562 cells treated with radiation and HMA had an accelerated cell death and induced a p53-independent apoptosis. This apoptotic pathway was dependent upon an initial hyperpolarization of the mitochondrial inner membrane, following the release of cytochrome c and subsequent caspase-3 activation. CONCLUSIONS: Two mechanisms of radiation-induced cell death in K562 cells, mitotic catastrophe and apoptosis, are regulated through distinct pathways, mitochondria and caspase-independent and -dependent, respectively. The findings of this study may provide new insights into improving the efficiency of radiotherapy in CML patients.

Immune reactions of lymphocytes and macrophages against PEG-grafted pancreatic islets.

Graft rejection is the major limiting factor in islet transplantation and is closely related with the recruitment and activation of T cells and macrophages against the graft. To reduce the immunogenicity of islets, we have grafted biocompatible polyethylene glycol (PEG) onto the collagen capsule of islets without changing the morphology and function of islets. In this study, we evaluated whether the grafted PEG molecules on the collagen capsule of islet could prevent the activation of immune cells, and investigated factors that are mainly related to the immune reaction in vitro. During the co-culture with lymphocytes, the morphology and viability of PEG-grafted islets were not damaged, and the amounts of IL-2 and TNF-alpha secreted from lymphocytes co-cultured with PEG-grafted islets were significantly lower than that of free islets. However, when both kinds of islets were cultured with macrophages, there were no significant differences in morphology, viability and the secreted amounts of cytokines and nitric oxide. In conclusion, the grafted PEG could inhibit activation of lymphocytes, which are essential in initiating the graft rejection process. However, the grafted PEG molecules could not completely prevent the infiltration of cytotoxic molecules into the islets.