Association between astigmatism and amblyopia.

Sapkota, Kishor,Kim, Douk Hoon The Korean Society of Clinical Health Science 2022 한국임상보건과학회지 Vol.10 No.1

Purpose: The aim of this study was to determine the association between stigmatism and amblyopia. Methods: It was a hospital based, cross-sectional retrospective study conducted in Nepal Eye Hospital. Medical record of amblyopic children aged 13 years or younger from were reviewed. Children with amblyopic eyes due to simple astigmatism were included. Relation between depth of amblyopia with magnitude and types of astigmatism, orientation of axis was determined. Out of 139 amblyopic eyes of 82 children, 93 were simple myopic astigmatism and remaining 42 were simple hyperopic astigmatism. Results: Mean age of patients was 7.38±2.61 years. Visual acuity improved by at least one line in Snellen chart in 4/5th of eyes after astigmatic correction. Moderate amblyopia was found to be present in 45% eyes while severe amblyopia in 16% of eyes. With the rule astigmatism was found to be present in 88% eyes. Mean astigmatism was 2.47±0.98D and majority of eyes (67.7%) had high astigmatism. Depth of amblyopia was not associated with magnitude of astigmatism (p > 0.05) but number of lines improved with astigmatic correction was correlated with the magnitude of astigmatism (p < 0.001). Risk of amblyopia is more in high myopic astigmatism. Conclusion: Presenting age of amblyopic children was late in Nepal. Depth of amblyopia was not associated with magnitude of astigmatism.

An experimental study on the performance of a zinc air fuel cell with inexpensive metal oxide catalysts and porous organic polymer separators

Sapkota, P.,Kim, H. Korean Society of Industrial and Engineering Chemi 2010 Journal of industrial and engineering chemistry Vol.16 No.1

A zinc air fuel cell (ZAFC) of taper-end structure was designed and manufactured with a polyamide-base engineering plastic. An air cathode with multiple layers of blended inexpensive metal oxides, MnO<SUB>2</SUB> and CeO<SUB>2</SUB>, showed a remarkably stable electricity-generating performance even at high current density. A cheap thin Nylon filter was found as a potential candidate for the separator in ZAFC because of its high stability and durability in the alkali electrolyte and proper pore size.

Antioxidant and Antimelanogenic Properties of Chestnut Flower Extract

SAPKOTA, Kumar,PARK, Se-Eun,KIM, Ji-Eun,KIM, Seung,CHOI, Han-Suk,CHUN, Hong-Sung,KIM, Sung-Jun Japan Society for Bioscience, Biotechnology, and A 2010 Bioscience, Biotechnology, and Biochemistry Vol.74 No.8

<P>In this study, we analyzed the antioxidant and antimelanogenic properties of a variety of solvent extracts of pre-bloom and full-bloom chestnut flowers. Among the solvent extracts, a pre-bloom methanol extract (preM) and an ethanol extract (preE) showed the highest amounts of phenolics (467.92±0.45 and 456.24±5.88 mg of gallic acid equivalent/g of extract) and flavonoids (60.96±1.86 and 41.59±8.57 mg of quercetin equivalent/g of extract). These extracts exhibited the highest DPPH radical and reducing activities, as well as the greatest mushroom tyrosinase inhibition activity. In addition, preE effectively protected the skin against ultraviolet (UV) rays. Further, extracts were tested for cytotoxicity on human melanoma cells (SK-MEL-2), and we observed that all the extracts were non-cytotoxic for the cells. Their effects on tyrosinase and melanin inhibitory action were further assessed, and we found that all the extracts reduced the tyrosinase activity and melanin formation of SK-MEL-2 cells as effectively as arbutin. Moreover, the protein level expression of tyrosinase decreased dramatically. However, the protein levels of the other melanogenic enzymes, tyrosinase-related protein 1 (TRP1) and dopachrome tautomerase (DCT), were not altered significantly. Therefore, the antimelanogenic effects of chestnut flower extracts were attributable to their inhibitory effects on tyrosinase <I>via</I> their anti-oxidative action, making them a strong candidate for use in food, cosmetics, and pharmaceutical applications.</P>

4-Hydroxy-2'-Nitrodiphenyl Ether Analogues as Novel Tyrosinase Inhibitors

Sapkota, Kiran,Lee, Eun-Young,Yang, Jae-Ho,Kwon, Young-Joo,Choi, Jong-Won,Na, Young-Hwa Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.5

Tyrosinase ubiquitously existing from microorganisms to animals and plants is known to be the most critical and rate limiting enzyme during melanin biosynthesis. In order to develop new tyrosinase inhibitor we have synthesized 14 diphenyl ether compounds possessing hydroxyl, bromo, and nitro groups in the structure. Among the compounds prepared, 18 and 19 have shown much stronger inhibition of tyrosinase monophenolase function than arbutin used as a positive control. Both compounds 18 and 19 possess para-hydroxyphenyl moiety in their structure, which might reinforce the importance of p-hydroxyphenyl group in the tyrosinase inhibitory process. In the DPPH radical scavenging activity test, none of the compounds even 18 and 19 showed significant antioxidant activity. The results suggest that elaborate adjustment of diphenyl ether analogues with proper substituents have potential to be developed as new skin whitening agents working on the tyrosinase function.

Effects of the Detoxified Extract of Rhus verniciflua on Regulation of Catecholamine Biosynthesis

Sapkota, Kumar,Kim, Seung,Kim, Jae-Sung,Kim, Myung-Kon,Chun, Hong-Sung,Kim, Sung-Jun The Korean Society for Applied Biological Chemistr 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.6

Rhus verniciflua Stokes (RVS) has traditionally been used as a food supplement and traditional herbal medicine for centuries in Korea, despite the fact that it contains the plant allergen, urushiol. Previously, we developed a new biological approach for the removal of urushiol from RVS. In this study, we investigated the effect of detoxified RVS on the expression of catecholamine biosynthetic enzymes in rat brain. Our results showed that RVS is a potent inducer of catecholamine production in rodent brain as indicated by the enhanced expression of the tyrosine hydroxylase (TH), aromatic amino acid decarboxylase (AADC) and dopamine ${\beta}$-hydroxylase (DBH) gene. Induction of TH and AADC in response to RVS was biphasic and transient, and maximal at 10 mg/kg for 4 h. We also detected consistent upregulation of TH and AADC mRNAs and proteins with RVS; however, DBH expression was not detected in the brain by immunostaining. Moreover, we examined the protective effect of detoxified RVS on rotenone induced cell toxicity in the cultured human dopaminergic cell line, SH-SY5Y. We found that rotenone induced cytotoxicity in SHSY5Y cells was suppressed by treatment with RVS. These results suggest that RVS may serve as an ideal adjuvant in regards to regulating the brain dopaminergic (DArgic) system and may contribute to neuroprotection in neurodegenerative diseases.

Aloe-emodin inhibits osteogenic differentiation and calcification of mouse vascular smooth muscle cells

Sapkota, Mahesh,Shrestha, Saroj Kumar,Yang, Ming,Park, Young Ran,Soh, Yunjo Elsevier 2019 european journal of pharmacology Vol.865 No.-

<P><B>Abstract</B></P> <P>Vascular calcification increases the risk of morbidity and mortality in patients with cardiovascular diseases, chronic kidney diseases, and diabetes. However, viable therapeutic methods to target vascular calcification are limited. Aloe-emodin (AE), an anthraquinone is a natural compound found in the leaves of Aloe-vera. In this study, we investigated the underlying mechanism of AE in the calcification of vascular smooth muscle cells (VSMCs) and murine thoracic aorta. We demonstrate that AE repressed not only the phenotypes of Ca<SUP>2+</SUP> induced calcification but also level of calcium in VSMCs. AE has no effect on cell viability in VSMC cells. Alizarin red, von Kossa stainings and calcium quantification showed that Ca<SUP>2+</SUP> induced vascular calcification is significantly decreased by AE in a concentration-dependent manner. In contrast, AE attenuated Ca<SUP>2+</SUP> induced calcification through inhibiting osteoblast differentiation genes such as SMAD4, collagen 1α, osteopontin (OPN), Runt-related transcription factor (RUNX-2) and Osterix. AE also suppressed Ca<SUP>2+</SUP> induced osteoblast-related protein expression including collagen 1α, bone morphogenic protein 2 (BMP-2), RUNX-2 and smooth muscle actin (SMA). Furthermore, Alizarin red, von Kossa stainings and calcium quantification showed that AE significantly inhibited the calcification of <I>ex vivo</I> ring formation in murine thoracic aorta, and markedly inhibited vitamin D<SUB>3</SUB> induced medial aorta calcification <I>in vivo</I>. Taken together, our findings suggest that AE may have therapeutic potential for the prevention of vascular calcification program.</P>

Policy implications for up-scaling of off-grid solar PV for increasing access to electricity in rural areas of Nepal: Best practices and lessons learned

Sapkota, Surya Kumar Korea Photovoltaic Society 2020 한국태양광발전학회지 Vol.6 No.1

Nepal has huge potential of hydro and other renewable energy resources including solar energy. However, only 70% of the total population have access to electricity despite the long history of hydropower development in the country. Still more than 37% population in rural areas and around 73% population in Karnali Province, one of the least developed provinces, are living without access to electricity despite taking several initiatives and implementing various policies by government supporting electrification in off-grid rural areas. Government together with donors and private sector has extensively been promoting the off-grid solar photovoltaic (PV) echnology in un-electrified areas to increase electricity access. So far, more than 900,000 households in rural areas of Nepal are getting electricity from stand-alone solar PV systems. However, there are many challenges including financial, technical, institutional, and governance barriers in Nepal. This study based on extensive review of literatures and author's own long working experiences in renewable energy sector in Nepal, shares the best practices and lessons of off-grid solar PV for increasing access to electricity in rural areas of Nepal. This study suggests that flexible financial instruments, financial innovations, bundling of PV systems for concentrating energy loads, adopting standards process, local capacity building, and combination of technology, financing and institutional aspects are a key for enhancing effectiveness of solar PV technology in rural areas of Nepal.

A Detoxified Extract of <i>Rhus verniciflua</i> Stokes Upregulated the Expression of BDNF and GDNF in the Rat Brain and the Human Dopaminergic Cell Line SH-SY5Y

SAPKOTA, Kumar,KIM, Seung,KIM, Myung-Kon,KIM, Sung-Jun Japan Society for Bioscience, Biotechnology, and A 2010 Bioscience, Biotechnology, and Biochemistry Vol.74 No.10

<P><I>Rhus verniciflua</I> Stokes (RVS) has traditionally been used as a food supplement and a traditional herbal medicine for centuries in Korea. This study attempted to evaluate the effects of RVS on the expression of Brain derived neurotrophic factor (BDNF) and Glial cell line-derived neurotrophic factor (GDNF) in SH-SY5Y cells and the rat brain. The results indicated that RVS is a potent inducer of Neurotrophic factor (NTF) production both <I>in vitro</I> and <I>in vivo</I>. Treatment with 10 μg/ml and 10 mg/kg RVS for 4 h of SH-SY5Y cells and rats yielded significant increases in BDNF and GDNF protein levels. We also detected BDNF and GDNF immunoreactive neurons in the rat brain. Both BDNF and GDNF-immunohistochemical staining was markedly enhanced in the animals treated with RVS. These results suggest that RVS serves as an ideal adjuvant in regard to regulating NTF expression, and can contribute to neuroprotection in neurodegenerative diseases.</P>

Effects of the Detoxified Extract of Rhus verniciflua on Regulation of Catecholamine Biosynthesis

Kumar Sapkota,김승,Jae-Sung Kim,김명곤,전홍성,Sung-Jun Kim 한국응용생명화학회 2009 Applied Biological Chemistry (Appl Biol Chem) Vol.52 No.6

Rhus verniciflua Stokes (RVS) has traditionally been used as a food supplement and traditional herbal medicine for centuries in Korea, despite the fact that it contains the plant allergen, urushiol. Previously, we developed a new biological approach for the removal of urushiol from RVS. In this study, we investigated the effect of detoxified RVS on the expression of catecholamine biosynthetic enzymes in rat brain. Our results showed that RVS is a potent inducer of catecholamine production in rodent brain as indicated by the enhanced expression of the tyrosine hydroxylase (TH), aromatic amino acid decarboxylase (AADC) and dopamine β-hydroxylase (DBH) gene. Induction of TH and AADC in response to RVS was biphasic and transient, and maximal at 10 mg/ kg for 4 h. We also detected consistent upregulation of TH and AADC mRNAs and proteins with RVS; however, DBH expression was not detected in the brain by immunostaining. Moreover, we examined the protective effect of detoxified RVS on rotenone induced cell toxicity in the cultured human dopaminergic cell line, SH-SY5Y. We found that rotenone induced cytotoxicity in SH-SY5Y cells was suppressed by treatment with RVS. These results suggest that RVS may serve as an ideal adjuvant in regards to regulating the brain dopaminergic (DArgic) system and may contribute to neuroprotection in neurodegenerative diseases.

Synthesis and anti-melanogenic activity of hydroxyphenyl benzyl ether anologues

( Kiran Sapkota ),( Eunmiri Roh ),( Eun Young Lee ),( Eun Mi Ha ),( Jae Ho Yang ),( Eung Seok Lee ),( Young Joo Kwon ),( Young Soo Kim ),( Young Hwa Na ) 영남대학교 약품개발연구소 2011 영남대학교 약품개발연구소 연구업적집 Vol.21 No.-