• Journal of Radiation Industry
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• v.10 no.4
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• pp.193-198
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• 2016

Perfusion magnetic resonance image of biological mechanism are independent of magnetic field strength in hyper acute ischemic stroke. 3.0 T magnetic field, however, does affect the SNRs (signal to noise ratio) and artifacts of PMRI (perfusion magnetic resonance image), which basically will influence the quantitative of PMRI. In this study, the effects of field strength on PMRI are analyzed. The effects of the diseases also are discussed. PMRI in WM(white matter), GM (gray matter), hyper acute ischemic stroke were companied with 1.5 T and 3.0 T on SNR. PMRI also was compared to the SI difference after setting ROI(region of interest) in left and right side of the brain. In conclusion, the SNRs and SI of the 3.0 T PMRI showed higher than those at 1.5 T. In summary, PMRI studies at 3.0 T is provided significantly improved perfusion evaluation when comparing with 1.5 T.

• Korean Journal of Pharmacognosy
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• v.50 no.1
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• pp.18-24
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• 2019

Andrographolide, the main compound of Andrographis paniculata (A. paniculata), shows various biological properties including anti-viral, anti-inflammatory, anti-diabetic, and hepatoprotective effects. Our previous study has shown that A. paniculata extract exerts antiaging effects by activation of stemness in epidermal stem cells (EpSCs). In this study, we investigated the effect of andrographolide as a main compound of A. paniculata on EpSCs and its mechnism of action using several in vitro assays. Andrographolide increased the proliferation of EpSCs and induced cell cycle progression. Additionally, andrographolide increased VEGF production and the expression of stem cell markers integrin ${\beta}1$ and p63. Furthermore, phosphorylation levels of extracellular signal-regulated kinase 1/2 (ERK1/2), S6 ribosomal protein (S6RP) and Akt were increased by andrographolide. Taken together, these results indicate that andrographolide-induced proliferation of EpSCs is mediated by the ERK1/2, Akt-dependent pathway with increased production of VEGF and upregulated stemness through integrin ${\beta}1$ and p63.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.9
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• pp.2846-2866
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• 2022

Caenorhabditis elegans exhibits sophisticated chemotaxis behavior through two parallel strategies, klinokinesis and klinotaxis, executed entirely by a small nervous circuit. It is therefore suitable for inspiring fast and energy-efficient solutions for autonomous navigation. As a random search strategy, the Lévy walk is optimal for diverse animals when foraging without external chemical cues. In this study, by combining these biological strategies for the first time, we propose a spiking neural network model for search and contour tracking of specific concentrations of environmental variables. Specifically, we first design a klinotaxis module using spiking neurons. This module works in conjunction with a klinokinesis module, allowing rapid searches for the concentration setpoint and subsequent contour tracking with small deviations. Second, we build a random exploration module. It generates a Lévy walk in the absence of concentration gradients, increasing the chance of encountering gradients. Third, considering local extrema traps, we develop a termination module combined with an escape module to initiate or terminate the escape in a timely manner. Experimental results demonstrate that the proposed model integrating these modules can switch strategies autonomously according to the information from a single sensor and control steering through output spikes, enabling the model worm to efficiently navigate across various scenarios.

• Molecules and Cells
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• v.26 no.2
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• pp.200-205
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• 2008

The mitogen-activated protein kinase (MAPK) signaling pathway is activated in response to extracellular stimuli and regulates various activities in eukaryotic cells. Following exposure to stimuli, MAPK is known to be activated via dual phosphorylation at a conserved TxY motif in the activation loop; both threonine and tyrosine residues are phosphorylated by an upstream kinase. However, the mechanism underlying dual phosphorylation is not clearly understood. In the budding yeast Saccharomyces cerevisiae, the Hog1 MAPK mediates the high-osmolarity glycerol (HOG) signaling pathway. Tandem mass spectrometry and phosphospecific immunoblotting were performed to quantitatively monitor the dynamic changes occurring in the phosphorylation status of the TxY motif of Hog1 on exposure to osmotic stress. The results of our study suggest that the tyrosine residue is preferentially and dynamically phosphorylated following stimulation, and this in turn leads to the dual phosphorylation. The tyrosine residue was hyperphosphorylated in the absence of a threonine residue; this result suggests that the threonine residue is critical for the control of signaling noise and adaptation to osmotic stress.

• BMB Reports
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• v.36 no.5
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• pp.514-519
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• 2003

The ribonucleotide reductase (RR) 2 gene of the HSV-2 strain G was cloned, sequenced, and expressed in an E. coli cell. The RR2 gene was located on the PstI 2.4 kb fragment, which was cloned and sequenced. The ORF of the gene was 1,011 bp and its termination codon was TAG; also, the CATATAA sequence was present in the promoter of the RR2 gene. A Poly A signal sequence (AATAAA) was found in the 3'-noncoding region. The RR2 proteins that were produced in the E. coli and Vero cells were confirmed using a Western blot analysis. SDS-PAGE revealed that the molecular weights of the fusion-RR2 that was produced in the E. coli cells were approximately 24 kDa and 38 kDa in the Vero cells. The RR2 proteins were soluble. The differences in the molecular weights might be due to modifications in the Vero cells.

• Korean Journal of Biological Psychiatry
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• v.6 no.1
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• pp.3-11
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• 1999

At the beginning, researches on the biology of depression or affective illness have focused mainly on the receptor functions and neuroendocrine activities. And the studies of the past years did not break new theoretical background, but the recent advances in the research on the molecular mechanisms underlying neural communication and signal transduction do add some insights to many established ideas. This article will overview some of the more recent advances in the clinical researches of depression. Our major concerns to be presented here include the followings : (1) alterations in the post-synaptic neural transduction ; (2) changes in the neurons of hypothalamic neuropeptides ; (3) decreased peptidase enzyme activities ; (4) associations of hypothalamic-pituitary-adrenal axis abnormalities with serotonin neurotransmission ; (5) role of serotonin transporter ; (6) changes in the responsiveness of intracellular calcium ion levels ; (7) the inositol deficiency theory of lithium and depression ; (8) the transcription factors including immediate early genes ; (9) recent genetic studies in some families. This brief overview will suggest that changes in DNA occur during antidepressant therapy. These changes at the DNA level initiating a cascade of events underlying antidepressant modality will give us the insights on the molecular biological basis of the pathogenesis of depression and cues for a new class of antidepressants.

• BMB Reports
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• v.53 no.9
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• pp.453-457
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• 2020

The right-handed double-helical structure of DNA (B-DNA), which follows the Watson-Crick model, is the canonical form of DNA existing in normal physiological settings. Even though an alternative left-handed structure of DNA (Z-DNA) was discovered in the late 1970s, Z-form nucleic acid has not received much attention from biologists, because it is extremely unstable under physiological conditions, has an ill-defined mechanism of its formation, and has obscure biological functions. The debate about the physiological relevance of Z-DNA was settled only after a class of proteins was found to potentially recognize the Z-form architecture of DNA. Interestingly, these Z-DNA binding proteins can bind not only the left-handed form of DNA but also the equivalent structure of RNA (Z-RNA). The Z-DNA/RNA binding proteins present from viruses to humans function as important regulators of biological processes. In particular, the proteins ADAR1 and ZBP1 are currently being extensively re-evaluated in the field to understand potential roles of the noncanonical Z-conformation of nucleic acids in host immune responses and human disease. Despite a growing body of evidence supporting the biological importance of Z-DNA/RNA, there remain many unanswered principal questions, such as when Z-form nucleic acids arise and how they signal to downstream pathways. Understanding Z-DNA/RNA and the sensors in different pathophysiological conditions will widen our view on the regulation of immune responses and open a new door of opportunity to develop novel types of immunomodulatory therapeutic possibilities.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.1
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• pp.31-41
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• 2002

Proline-rich proteins (PRPs) are major components of human saliva. In order to know the biological roles of PRPs, we explored the expression pattern and functional protein structures of PRPs by the immunohistochemical and various molecular biological methods. Polyclonal antibody against human gPRP was generated from rabbit by the injection of oral exfoliated cells specially treated by urea and SDS buffer. The PRPs began to be expressed both in the acinar cells and ductal cells from the EIDS (Early Intermediate Developmental Stage) of fetal salivary glands and became intense in the salivary epithelium in the LDS (Late Developmental Stage) and adult salivary glands. The polyclonal antibody against the gPRP showed the cross-reactivity with aPRP and bPRP, these results were relevant to the high homology among subtypes of PRP. However, the simulated protein structures of PRPs showed the characteristic repetitive whorling domains except the N-terminal signal peptide. The whorling domains were also contained the multiple amino acids of glutamine and glycine, which may provide the receptor binding or cross-linking sites of PRPs.

• BMB Reports
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• v.45 no.12
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• pp.748-753
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• 2012

A sequence of 10 amino acids at the C-terminus region of methylglyoxal synthase from Escherichia coli (EMGS) provides an arginine, which plays a crucial role in forming a salt bridge with a proximal aspartate residue in the neighboring subunit, consequently transferring the allosteric signal between subunits. In order to verify the role of arginine, the gene encoding MGS from a thermophile species, Thermus sp. GH5 (TMGS) lacking this arginine was cloned with an additional 30 bp sequence at the 3'-end and then expressed in form of a fusion TMGS with a 10 residual segment at the C-terminus ($TMGS^+$). The resulting recombinant enzyme showed a significant increase in cooperativity towards phosphate, reflected by a change in the Hill coefficient (nH) from 1.5 to 1.99. Experiments including site directed mutagenesis for Asp-10 in TMGS and $TMGS^+$, two dimentional structural survey, fluorescence and irreversible thermoinactivation were carried out to confirm this pathway.

• Molecules and Cells
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• v.26 no.6
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• pp.590-594
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• 2008

brc-2, an ortholog of BRCA2 in Caenorhabditis elegans, is essential in the maintenance of genetic integrity. In C. elegans, cellular location correlates with meiotic progression, and transgene-induced cosuppression is observed in the germ line but not in somatic cells. We used these unique features to dissect the role of brc-2 in the germ line from that in somatic cells. In situ hybridization of wild type animals revealed that brc-2 gene expression was higher in oocytes than in other germline cells, and was barely detectable in mitotic cells. In contrast, germ cells containing multicopies of the brc-2 transgene showed no significant in situ hybridization signal at any oogenesis stage, confirming that brc-2 expression was functionally cosuppressed in the transgenic germ line. RAD-51 foci formation in response to DNA damage was abrogated in brc-2-cosuppressed germ cells, whereas wild-type germ cells showed strong RAD-51 foci formation. These germ cells exhibited massive chromosome fragmentation and decompaction instead of six bivalent chromosomes in diakinesis. Accordingly, lethality was observed after the early stage of germline development. These results suggest that brc-2 plays essential roles in chromosome integrity in early prophase, and therefore is crucial in meiotic progression and embryonic survival.