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138 result(s) for "Chui, Chung"
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Recent advances in green nanoparticulate systems for drug delivery: efficient delivery and safety concern
Nanotechnology manipulates therapeutic agents at the nanoscale for the development of nanomedicines. However, there are current concerns over nanomedicines, mainly related to the possible toxicity of nanomaterials used for health medications. Due to their small size, they can enter the human body more readily than larger sized particles. Green chemistry encompasses the green synthesis of drug-loaded nanoparticles by reducing the use of hazardous materials in the synthesis process, thus reducing the adverse health impacts of pharmaceutics. This would greatly expand their potential in biomedical treatments. This review highlights the potential risks of nanomedicine formulations to health, delivery routes of green nanomedicines, recent advances in the development of green nanoscale systems for biomedical applications and future perspectives for the green development of nanomedicines.
Targeting DNA Binding for NF-κB as an Anticancer Approach in Hepatocellular Carcinoma
Quinoline core has been shown to possess a promising role in the development of anticancer agents. However, the correlation between its broad spectrum of bioactivity and the underlying mechanism of actions is poorly understood. The present study, with the use of bioinformatics approaches, reported a series of designed molecules which integrated quinoline core and sulfonyl moiety, with the objective of evaluating the substituent and linker effects on anticancer activities and associated mechanistic targets. We identified potent compounds (1h, 2h, 5 and 8) exhibiting significant anticancer effects towards liver cancer cells (Hep3B) with the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) relative values of cytotoxicity below 0.40, a value in the range of doxorubicin positive control with the value of 0.12. Bulky substituents and the presence of bromine atom, as well as the presence of sulfonamide linkage, are likely the favorable structural components for molecules exerting a strong anticancer effect. To the best of our knowledge, our findings obtained from chemical synthesis, in vitro cytotoxicity, bioinformatics-based molecular docking analysis (similarity ensemble approach, SEA),and electrophoretic mobility shift assay provided the first evidence in correlation to the anticancer activities of the selected compound 5 with the modulation on the binding of transcription factor NF-κB to its target DNA. Accordingly, compound 5 represented a lead structure for the development of quinoline-based NF-κB inhibitors and this work added novel information on the understanding of the mechanism of action for bioactive sulfonyl-containing quinoline compounds against hepatocellular carcinoma.
Development of a Novel Quinoline Derivative as a P-Glycoprotein Inhibitor to Reverse Multidrug Resistance in Cancer Cells
Multidrug resistance (MDR) is one of conventional cancer chemotherapy’s limitations. Our group previously synthesized a series of quinoline-based compounds in an attempt to identify novel anticancer agents. With a molecular docking analysis, the novel compound 160a was predicted to target p-glycoprotein, an MDR candidate. The purpose of this study is to evaluate 160a’s MDR reversal effect and investigate the underlying mechanism at the molecular level. To investigate 160a’s inhibitory effect, we used a series of parental cancer cell lines (A549, LCC6, KYSE150, and MCF-7), the corresponding doxorubicin-resistant cell lines, an MTS cytotoxicity assay, an intracellular doxorubicin accumulation test, and multidrug resistance assays. The Compusyn program confirmed, with a combination index (CI) value greater than 1, that 160a combined with doxorubicin exerts a synergistic effect. Intracellular doxorubicin accumulation and transported calcein acetoxymethyl (AM) (a substrate for p-glycoprotein) were both increased when cancer cells with MDR were treated with compound 160a. We also showed that compound 160a’s MDR reversal effect can persist for at least 1 h. Taken together, these results suggest that the quinoline compound 160a possesses high potential to reverse MDR by inhibiting p-glycoprotein-mediated drug efflux in cancer cells with MDR.
Initial Treatment of Immune Thrombocytopenic Purpura with High-Dose Dexamethasone
In this study of the efficacy of a four-day course of high-dose dexamethasone for newly diagnosed immune thrombocytopenic purpura, the treatment response was sustained for two to five years in half of the 106 patients who had an initial response. A four-day course of dexamethasone for newly diagnosed ITP, with responses sustained for years in many cases. Immune thrombocytopenic purpura results from antiplatelet autoantibodies, usually of the IgG class, that cause platelet destruction in the reticuloendothelial system. 1 Corticosteroids, in a dose equivalent to 1 to 2 mg of prednisone per kilogram of body weight daily, increase the platelet count in about 75 percent of adults and are the conventional initial treatment for immune thrombocytopenic purpura. 2 , 3 Since most responses occur after 7 to 10 days of treatment, the lack of a clinically significant increase in the number of platelets after three weeks of treatment is considered to represent failure of corticosteroid treatment. 1 , 4 Many patients have a . . .
Development of 8-benzyloxy-substituted quinoline ethers and evaluation of their antimicrobial activities
A series of 8-benzyloxy-substituted quinoline ethers ( 2a – n ) compounds were synthesized. All synthesized compounds were screened in vitro for their preliminary antimicrobial activities against two Gram-negative bacteria ( Pseudomonas aeruginosa and Escherichia coli ), two Gram-positive bacteria ( Staphylococcus aureus and Staphylococcus epidermidis ), and a fungal species ( Aspergillus niger ). Among all synthesized compounds, compound 2e showed a significant growth inhibitory activity with MIC value 3.125 μg/mL which was comparable to 8-hydroxyquinoline (2.5 μg/mL) and terbinafine (1.25 μg/mL) against A. niger .
Expression of Insulin-Like Growth Factor Binding Protein-5 (IGFBP5) Reverses Cisplatin-Resistance in Esophageal Carcinoma
Cisplatin (CDDP) is one of the front-line chemotherapeutic drugs used in the treatment of esophageal squamous cell carcinoma (ESCC). Occurrence of resistance to CDDP has become one of the main challenges in cancer therapy. In this study, the gene expression profile of CDDP-resistant ESCC cells was investigated and molecular approaches were explored in an attempt to reverse the CDDP resistance. A CDDP-resistant SLMT-1/CDDP1R cell line was established from SLMT-1 cells by subculturing in the medium containing an increasing concentration of CDDP (0.1–1μg/mL). Mitochondrial (MTS) cytotoxicity assay, cell proliferation assay and cell morphology were used to assess the acquisition of cisplatin-resistance. The most differentially expressed gene in SLMT-1/CDDP1R cells was identified by cDNA microarray analysis compared with the parental SLMT-1 cells and validated by quantitative real-time polymerase chain reaction (qPCR). Association between expression of the most differentially expressed target gene to cisplatin-resistance was verified by RNA interference. An attempt to reversecisplatin-resistance phenotypes was made by using the vector expressing the most downregulated target gene in the CDDP-resistant cells. A CDDP-resistant ESCC cell line, SLMT-1/CDDP1R, was established with 2.8-fold increase CDDP-resistance (MTS50 = 25.8 μg/mL) compared with the parental SLMT-1 cells. cDNA microarray analysis revealed that IGFBP5 showed the highest level of downregulation in SLMT-1/CDDP1R cells compared with the parental SLMT-1 cells. Suppression of IGFBP5 mediated by IGFBP5-targeting siRNA in parental SLMT-1 cells confirmed that IGFBP5 suppression in ESCC cells would induce CDDP-resistance. More importantly, upregulation of IGFBP5 using IGFBP5 expression vector reduced cisplatin-resistance in SLMT-1/CDDP1R cells by 41%. Thus, our results demonstrated that IGFBP5 suppression is one of the mechanisms for the acquisition of cisplatin-resistance in ESCC cells. Cisplatin-resistance phenotype can be reversed by increasing the expression level of IGFBP5. The overall findings of this study thus offered a new direction for reversing the CDDP resistance in ESCC and possibly in other cancer types with further investigations in future.
The Loss of Cellular Junctions in Epithelial Lung Cells Induced by Cigarette Smoke Is Attenuated by Corilagin
Cigarette smoke (CS) contains over 4700 compounds, many of which can affect cellular redox balance through free radicals production or through the modulation of antioxidant enzymes. The respiratory tract is one of the organs directly exposed to CS and it is known that CS can damage the integrity of lung epithelium by affecting cell junctions and increasing epithelium permeability. In this study, we have used a human lung epithelial cell line, Calu-3, to evaluate the effect of CS on lung epithelial cell junctions levels, with special focus on the expression of two proteins involved in intercellular communication: connexins (Cx) 40 and 43. CS exposure increased Cx40 gene expression but not of Cx43. CS also induced NFκB activation and the formation of 4HNE-Cxs adducts. Since corilagin, a natural polyphenol, is able to inhibit NFκB activation, we have determined whether corilagin could counteract the effect of CS on Cxs expression. Corilagin was able to diminish CS induced Cx40 gene expression, 4HNE-Cx40 adducts formation, and NFκB activation. The results of this study demonstrated that CS induced the loss of cellular junctions in lung epithelium, possibly as a consequence of Cx-4HNE adducts formation, and corilagin seems to be able to abolish these CS induced alterations.
Sensitization of Candida albicans to terbinafine by berberine and berberrubine
Candida albicans (C. albicans) is an opportunistic fungal pathogen, particularly observed in immunocompromised patients. C. albicans accounts for 50-70% of cases of invasive candidiasis in the majority of clinical settings. Terbinafine, an allylamine antifungal drug, has been used to treat fungal infections previously. It has fungistatic activity against C. albicans. Traditional Chinese medicines can be used as complementary medicines to conventional drugs to treat a variety of ailments and diseases. Berberine is a quaternary alkaloid isolated from the traditional Chinese herb, Coptidis Rhizoma, while berberrubine is isolated from the medicinal plant Berberis vulgaris, but is also readily derived from berberine by pyrolysis. The present study demonstrates the possible complementary use of berberine and berberrubine with terbinafine against C. albicans. The experimental findings assume that the potential application of these alkaloids together with reduced dosage of the standard drug would enhance the resulting antifungal potency.
Mid-infrared light generation by nonlinear optical frequency conversion in intersubband indium gallium arsenide/aluminum gallium arsenide quantum wells
Compact diode laser based mid-infrared sources have many potential applications from pollution monitoring and intelligent process controls to laser radar and non-invasive medical diagnosis. Recent developments in long wavelength diode lasers have pushed room temperature continuous operation to wavelengths around 2.3 $\\mu$ m. However, room temperature operation of diode lasers at much longer wavelengths may not be possible due to Auger recombination. An alternative approach is to use nonlinear optical frequency conversion of efficient near-infrared diode lasers to generate mid-infrared light. Quantum wells (QWs) are an attractive material for frequency conversion. QWs have demonstrated optical nonlinearities several orders of magnitude larger than bulk materials arising from intersubband transitions (ISBTs). ISBTs are typically limited to long wavelengths. However, using strained QW materials, conduction band offsets can be increased so that ISBT energies overlap diode laser wavelengths. Thus, integrated diode laser pumps and QW nonlinear optical frequency converters could possibly function as compact mid-infrared sources. This thesis describes the development of highly strained InGaAs/AlGaAs QWs grown on GaAs for frequency conversion applications. Studies to optimize growth conditions are performed, resulting in improved material quality and narrow transition linewidths. The intersubband absorption of QWs with varying structures is characterized experimentally and modelled with a simple theory, and short wavelength ISBTs near 2 $\\mu$ m are demonstrated. The nonlinear optical properties are measured by second harmonic generation (SHG) with both a free electron laser and a CO $\\sb2$laser, and large nonlinearities at wavelengths as short as 1.85 $\\mu$ m are observed. Finally, mid-infrared generation by difference frequency mixing of two near-infrared wavelengths is demonstrated for the first time in any QW system.
Evidence of higher-order topology in multilayer WTe2 from Josephson coupling through anisotropic hinge states
Td-WTe 2 (non-centrosymmetric and orthorhombic), a type-II Weyl semimetal, is expected to have higher-order topological phases with topologically protected, helical one-dimensional hinge states when its Weyl points are annihilated. However, the detection of these hinge states is difficult due to the semimetallic behaviour of the bulk. In this study, we have spatially resolved the hinge states by analysing the magnetic field interference of the supercurrent in Nb–WTe 2 –Nb proximity Josephson junctions. The Josephson current along the a axis of the WTe 2 crystal, but not along the b axis, showed a sharp enhancement at the edges of the junction, and the amount of enhanced Josephson current was comparable to the upper limits of a single one-dimensional helical channel. Our experimental observations suggest a higher-order topological phase in WTe 2 and its corresponding anisotropic topological hinge states, in agreement with theoretical calculations. Our work paves the way for the study of hinge states in topological transition-metal dichalcogenides and analogous phases. Transport measurements and calculations show that WTe 2 may be a higher-order topological insulator with topological hinge states.