Injectable hydrogels for islet transplantation: a concise review

Prakash Shrestha,Shobha Regmi,정지헌 한국약제학회 2020 Journal of Pharmaceutical Investigation Vol.50 No.1

Islet cell transplantation is a promising alternative for the treatment of type 1 diabetic mellitus which is caused by complete absence or reduced insulin production by pancreas. After Shapiro and his team carried out successful islet transplantation and achieved positive clinical outcomes, much progress have been made in the procedure from isolation to clinical transplantation. Since 2000, more than 1500 patients have undergone islet transplantation. Thus, this therapeutic approach has progressed from mere curiosity to therapeutic achievement. However, many hurdles have yet to be crossed, such as instant blood-mediated inflammatory reaction, immune reactions, side effects of immunosuppressant drugs, lack of donors, islet quality variability, and others. Isolated islet cells face huge mechanical, immunological and bio-physiological challenges that potentially compromise long-term viability and functionality post-transplantation. In addition, preservation of islet cell microenvironment, including extracellular matrix (ECM), is one of the most challenging aspects of the transplantation. ECM is composed of water, proteins, and polysaccharides, and is essential for biochemical, mechanical, and physiological well-being of organs and tissues. ECM also organizes morphological integrity and physiological function by either binding with growth factors or promoting cell surface interactions that result in signal transduction and the regulation of gene transcription. In general, we can say ECM and other biochemical substances constitute a tissue-specific microenvironment that is responsible for growth and proliferation. In this review, we focus on ECM mimicking scaffolds, injectable natural and synthetic hydrogels, their recent advancements, some drawbacks, and future perspectives.

Curcumin-laden ECM-mimicking microfibers assemble with mesenchymal stem cells to generate heterospheroids and enhance cell viability and function

Prakash Shrestha,Shiva Pathak,Shobha Regmi,베드리칸난,Tiep Tien Nguyen,Simmyung Yook,김종오,Jee-Heon Jeong 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-

Extracellular matrix (ECM) is an integral part of cell biology that not only provides physical stability tocells, but also aids in cell-to-cell and cell-to-essential-protein interactions in the cellular microenvironment. To mimic the natural ECM conditions, we prepared morphologically similar artificial polymericmicrofibers and used polydopamine to coat them with collagen to enhance cell–polymeric fiber interactions. Heterospheroids (HSs) of ECM-mimicking microfibers and mesenchymal stem cells (MSCs) wereprepared using the spontaneous aggregation method. The results revealed well-organized MSCmicrofiberHSs that enhanced the viability of the MSCs. In addition, when curcumin, an antioxidant drug,was loaded into the microfibers and HSs were prepared, the viability of the MSCs was further enhanced,as revealed by a reduction in the expression of apoptotic protein Bax. Furthermore, the expression of antiapoptoticproteins Bcl-2 and HO-1 increased significantly in the HSs containing the drug-loaded microfibers. Overall, our study suggests a novel strategy for improving the success of MSC therapy using ECMmimickingartificial microfibers.

Combination Therapy of Sustained Release Immune Modulatory Drug and PEGylation of Islets in Presence of Hydrogel for Treatment of Type 1 Diabetes Mellitus

Prakash Shrestha,Shiva Pathak,Shobha Regmi,정지헌 한국고분자학회 2020 한국고분자학회 학술대회 연구논문 초록집 Vol.45 No.2

Dengue Virus Serotypes 1 and 2 Responsible for Major Dengue Outbreaks in Nepal: Clinical, Laboratory, and Epidemiological Features

Dumre, Shyam Prakash,Bhandari, Renu,Shakya, Geeta,Shrestha, Sanjaya Kumar,Cherif, Mahamoud Sama,Ghimire, Prakash,Klungthong, Chonticha,Yoon, In-Kyu,Hirayama, Kenji,Na-Bangchang, Kesara Allen Press, etc 2017 The American journal of tropical medicine and hygi Vol.97 No.4

On component isolation of conceptual advanced reactors

Shrestha Samyog,Kurt Efe G.,Prakash Arun,Irfanoglu Ayhan 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

Implementation of component isolation in nuclear industry is challenging due to gaps in research and the lack of specific guidelines. In this study, parameters affecting component-level isolation of advanced reactor vessels are identified based on a representative numerical model with explicit consideration of nonlinear soil-structure interaction (SSI). The objective of this study is to evaluate the effectiveness of, and to identify potential limitations of using conventional friction pendulum bearings to seismically isolate vessels. It is found that slender vessels or components are particularly vulnerable to rotational accelerations at the isolation interface, which are caused by rotation of the sub-structure and by excitation of higher modes in the horizontal direction of the seismically isolated system. Component isolation is found to be more effective for relatively stiffer vessels and at sites with stiff soil. Considering that conventional isolators are deficient in resisting axial tension, it is observed that the optimum location for supporting a component to achieve seismic isolation, is at a cross-sectional plane passing through the center of mass of the vessel. These findings are corroborated by numerous simulations of the response of seismically isolated reactor vessels at different nuclear power plant sites subject to a variety of ground motions.

Biosynthesis of flavone C-glucosides in engineered Escherichia coli

Shrestha, Anil,Pandey, Ramesh Prasad,Dhakal, Dipesh,Parajuli, Prakash,Sohng, Jae Kyung Springer-Verlag 2018 Applied microbiology and biotechnology Vol.102 No.3

<P>Two plant-originated C-glucosyltransferases (CGTs) UGT708D1 from Glycine max and GtUF6CGT1 from Gentiana triflora were accessed for glucosylation of selected flavones chrysin and luteolin. Uridine diphosphate (UDP)-glucose pool was enhanced in Escherichia coli cell cytosol by introducing heterologous UDP-glucose biosynthetic genes, i.e., glucokinase (glk), phosphoglucomutase (pgm2), and glucose 1-phosphate uridylyltransferase (galU), along with glucose facilitator diffusion protein from (glf) from different organisms, in a multi-monocistronic vector with individual T-7 promoter, ribosome binding site, and terminator for each gene. The C-glucosylated products were analyzed by high-performance liquid chromatography-photodiode array, high-resolution quadruple time-of-flight electrospray ionization mass spectrometry, and one-dimensional nuclear magnetic resonance analyses. Fed-batch shake flask culture showed 8% (7 mg/L; 16 mu M) and 11% (9 mg/L; 22 mu M) conversion of chrysin to chrysin 6-C-beta-D-glucoside with UGT708D1 and GtUF6CGT1, respectively. Moreover, the bioengineered E. coli strains with exogenous UDP-glucose biosynthetic genes and glucose facilitator diffusion protein enhanced the production of chrysin 6-C-beta-D-glucoside by approximately 1.4-fold, thus producing 10 mg/L (12%, 24 mu M) and 14 mg/L (17%, 34 mu M) by UGT708D1 and GtUF6CGT1, respectively, without supplementation of additional UDP-glucose in the medium. The biotransformation was further elevated when the bioengineered strain was scaled up in lab-scale fermentor at 3 L volume. HPLC analysis of fermentation broth extract revealed 50% (42 mg/L, 100 mu M) conversion of chrysin to chrysin 6-C-beta-D-glucoside at 48 h upon supplementation of 200 mu M of chrysin. The maximum conversion of luteolin was 38% (34 mg/L, 76 mu M) in 50-mL shake flask fermentation at 48 h. C-glucosylated derivative of chrysin was found to be more soluble and more stable to high temperature, different pH range, and beta-glucosidase enzyme, than O-glucosylated derivative of chrysin.</P>

Characterization of regioselective flavonoid <i>O-</i>methyltransferase from the <i>Streptomyces</i> sp. KCTC 0041BP

Darsandhari, Sumangala,Dhakal, Dipesh,Shrestha, Biplav,Parajuli, Prakash,Seo, Joo-Hyun,Kim, Tae-Su,Sohng, Jae Kyung Elsevier 2018 Enzyme and microbial technology Vol.113 No.-

<P>A flavonoid comprises polyphenol compounds with pronounced antiviral, antioxidant, anticarcinogenic, and anti-inflammatory effects. The flavonoid modification by methylation provides a greater stability and improved pharrnacokinetic properties. The methyltransferase from plants or microorganisms is responsible for such substrate modifications in a regiospecific or a promiscuous manner. GerMIII, originally characterized as a putative methyltransferase in a dihydrochalcomycin biosynthetic gene cluster of the Streptomyces sp. KCTC 0041BP, was tested for the methylation of the substrates of diverse chemical structures. Among the various tested substrates, flavonoids emerged as the favored substrates for methylation. Further, among the flavonoids, quercetin is the most favorable substrate, followed by luteolin, myricetin, quercetin 3-O-beta-D-glucoside, and fisetin, while only a single product was formed in each case. The products were confirmed by HPLC and mass-spectrometry analyses. A detailed NMR spectrometric analysis of the methylated quercetin and luteolin derivatives confirmed the regiospecific methylation at the 4'-OH position. Modeling and molecular docking provided further insight regarding the most favorable mechanism and substrate architecture for the enzymatic catalysis. Accordingly, a double bond between the C-2 and the C-3 and a single-ring-appended conjugate-hydroxyl group are crucial for the favorable enzymatic conversions of the GerMIII catalysis. Thus, in this study, the enzymatic properties of GerMill and a mechanistic overview of the regiospecific modification that was implemented for the acceptance of quercetin as the most favorable substrate are presented.</P>

Morphological Characterization of Anther Derived Plants in Minipaprika (Capsicum annuum L.)

Binod Prasad Luitel,Prakash Babu Adhikari,Surendra Lal Shrestha,Won Hee Kang 한국육종학회 2012 한국육종학회지 Vol.44 No.4

This study was done to characterize the anther derived regenerants (R1) including haploids and spontaneous diploids of minipaprika (cvs.‘Vine sweet-red’ ‘Vine sweet-yellow’ and ‘Vine sweet-orange’) in glasshouse. Eleven haploids (three, seven and one from red, yellow and orange, respectively) and sixteen spontaneous diploids (five, nine and two from red, yellow and orange, respectively) were grown in plastic pot with three (red, yellow and orange) anther donor (R0) F1minipaprika varieties. Regenerants were characterized for their plant and fruit characters as well as their fruit color and shape. The homozygosity of spontaneous diploid plants of each population was assessed using simple-sequence repeat (SSR) marker analysis. Haploid plants were characterized by reduced plant height, small leaves, short petiole and internode and small flower bud and all haploids showed the sterility and vice-versa in spontaneous diploid lines. The fruit biometrical traits exhibited greater variation within the spontaneous diploid plants and average value of quantitative traits is lower than standard varieties. MR-4 gave the highest yield (150.5 g) per plant followed by MY-6 (140.0 g) and MY-8 (130.5 g) and the lowest in MY-5 (31.5 g). Morphological marker such as fruit color further determinedthe microspore origin of androgenic diploids obtained in anther culture of ‘Vine sweet-red’. Of the fifteen spontaneous diploid plants, fourteen plants were identified as doubled haploids using microsatellite markers (SSR), and these homozygous lines are recommended to use in minipaprika breeding program.

Helicobacter pylori Infection and Gastric Mucosal Atrophy in Two Ethnic Groups in Nepal

Miftahussurur, Muhammad,Sharma, Rabi Prakash,Shrestha, Pradeep Krishna,Maharjan, Ramesh Kumar,Shiota, Seiji,Uchida, Tomohisa,Sato, Hiroki,Yamaoka, Yoshio Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.17

Serum anti-Helicobacter pylori antibodies and pepsinogens (PGs) have been used as gastric cancer screening and gastric mucosal status markers. Nepal is a low risk country for gastric cancer. However, the mountainous populace in the northern region culturally linked to Tibet as well as Bhutan, a neighboring country, have a high risk of GC. We collected gastric biopsy specimens and sera from 146 dyspeptic patients living in Kathmandu, Nepal. We also examined the sera of 80 volunteers living in the mountainous regions of the Himalayas. The optimal cut-off was calculated for serum biomarkers against the histology. Kathmandu patients (43.8%) were serologically positive for H. pylori infection, which was significantly lower than that for the mountainous (61.3%, P = 0.01). The same results also found in the prevalence of PG-positivity, PG I levels and PG I/II ratios (P = 0.001, P<0.0001 and P = 0.03, respectively). Moreover, the PG I/II ratios were significantly, and inversely correlated with the OLGA score (r = -0.33, P<0.009). The low incidence of gastric cancer in Nepal can be attributed to low gastric mucosal atrophy. However, the mountainous subjects have high-risk gastric mucosal status, which could be considered a high-risk population in Nepal.

Single-dose intraperitoneal delivery of FK506-encapsulated polymeric microspheres for the alleviation of murine colitis

Shiva Pathak,Shobha Regmi,Mahesh Raj Nepal,Prakash Shrestha,Jeong Uk Choi,Simmyung Yook,Jee-Heon Jeong 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.91 No.-

Based on the severity of the disease progression, the treatment of ulcerative colitis involvesadministration of single or multiple therapeutic agents. In refractory cases of ulcerative colitis, FK506(FK) is the drug of choice in clinics. To maintain a long-term stable blood concentration of FK and toreduce its dosing frequency, we propose single-dose injection of FK-loaded biodegradable microspheres(FK-Ms). FK-Ms were intraperitoneally-injected into mice fed with dextran-sulfate sodium (DSS). Pharmacokinetics study revealed presence of FK in blood for over 20 days. The single intraperitonealinjection of the drug-loaded microspheres effectively alleviated DSS-induced murine colitis. Mechanistically, the single injection of FK-Ms inhibited the infiltration of T cells into colon andattenuated differentiation of T cells into interferon-g secreting Th1 and interleukin-17A secreting Th17cells in colon-draining mesenteric lymph nodes. Therefore, administration of prolonged-release typemicrospheres can be considered as an alternative for the effective treatment of inflammatory boweldiseases.