ssDNA reeling is an intermediate step in the reiterative DNA unwinding activity of the WRN-1 helicase.

RecQ helicases are highly conserved between bacteria and humans. These helicases unwind various DNA structures in the 3' to 5'. Defective helicase activity elevates genomic instability and is associated with predisposition to cancer and/or premature aging. Recent single-molecule analyses have revealed the repetitive unwinding behavior of RecQ helicases from Escherichia coli to humans. However, the detailed mechanisms underlying this behavior are unclear. Here, we performed single-molecule studies of WRN-1 Caenorhabditis elegans RecQ helicase on various DNA constructs and characterized WRN-1 unwinding dynamics. We showed that WRN-1 persistently repeated cycles of DNA unwinding and rewinding with an unwinding limit of 25 to 31 bp per cycle. Furthermore, by monitoring the ends of the displaced strand during DNA unwinding we demonstrated that WRN-1 reels in the ssDNA overhang in an ATP-dependent manner. While WRN-1 reeling activity was inhibited by a C. elegans homolog of human replication protein A, we found that C. elegans replication protein A actually switched the reiterative unwinding activity of WRN-1 to unidirectional unwinding. These results reveal that reeling-in ssDNA is an intermediate step in the reiterative unwinding process for WRN-1 (i.e., the process proceeds via unwinding-reeling-rewinding). We propose that the reiterative unwinding activity of WRN-1 may prevent extensive unwinding, allow time for partner proteins to assemble on the active region, and permit additional modulation in vivo.

Molecular characteristics of reiterative DNA unwinding by the Caenorhabditis elegans RecQ helicase.

The RecQ family of helicases is highly conserved both structurally and functionally from bacteria to humans. Defects in human RecQ helicases are associated with genetic diseases that are characterized by cancer predisposition and/or premature aging. RecQ proteins exhibit 3'-5' helicase activity and play critical roles in genome maintenance. Recent advances in single-molecule techniques have revealed the reiterative unwinding behavior of RecQ helicases. However, the molecular mechanisms involved in this process remain unclear, with contradicting reports. Here, we characterized the unwinding dynamics of the Caenorhabditis elegans RecQ helicase HIM-6 using single-molecule fluorescence resonance energy transfer measurements. We found that HIM-6 exhibits reiterative DNA unwinding and the length of DNA unwound by the helicase is sharply defined at 25-31 bp. Experiments using various DNA substrates revealed that HIM-6 utilizes the mode of 'sliding back' on the translocated strand, without strand-switching for rewinding. Furthermore, we found that Caenorhabditis elegans replication protein A, a single-stranded DNA binding protein, suppresses the reiterative behavior of HIM-6 and induces unidirectional, processive unwinding, possibly through a direct interaction between the proteins. Our findings shed new light on the mechanism of DNA unwinding by RecQ family helicases and their co-operation with RPA in processing DNA.

Chronic Pain Patients' Gaze Patterns toward Pain-Related Information: Comparison between Pictorial and Linguistic Stimuli.

BACKGROUND AND OBJECTIVES: The attentional bias and information processing model explained that individuals who interpret pain stimuli as threatening may increase their attention toward pain-related information. Previous eye tracking studies found pain attentional bias among individuals with chronic pain; however, those studies investigated this phenomenon by using only one stimulus modality. Therefore, the present study investigated attentional engagement to pain-related information and the role of pain catastrophizing on pain attentional engagement to pain-related stimuli among chronic pain patients by utilizing both linguistic and visual stimulus. MATERIALS AND METHODS: Forty chronic pain patients were recruited from the rehabilitation center, the back pain clinic, and the rheumatology department of Chung-Ang University Hospital in Seoul, Korea. Patients observed pictures of faces and words displaying pain, presented simultaneously with neutral expressions, while their eye movements were measured using the eye tracking system. A t-test and ANOVA were conducted to compare stimulus pairs for the total gaze duration. Results revealed that chronic pain patients demonstrated attentional preference toward pain words but not for pain faces. An ANOVA with bias scores was conducted to investigate the role of pain catastrophizing on attentional patterns. Results indicated that chronic pain patients with high pain catastrophizing scores gazed significantly longer at pain- and anger-related words than neutral words compared to those with low pain catastrophizing scores. The same patterns were not observed for the facial expression stimulus pairs. CONCLUSIONS: The results of the present study revealed attentional preference toward pain-related words and the significant role of pain catastrophizing on pain attentional engagement to pain-related words. However, different patterns were observed between linguistic and visual stimuli. Clinical implications related to use in pain treatment and future research suggestions are discussed.

Diphyllobothrium nihonkaiense: wide egg size variation in 32 molecularly confirmed adult specimens from Korea.

The eggs of Diphyllobothrium nihonkaiense were reported to be smaller than those of the classical Diphyllobothrium latum in general. However, verification using a large number of adult tapeworms is required. We assessed the egg size variation in 32 adult specimens of D. nihonkaiense recovered from Korean patients in 1975-2014. The diagnosis of individual specimens was based on analysis of the mitochondrial cytochrome c oxidase 1 gene sequence. Uterine eggs (n = 10) were obtained from each specimen, and their length and width were measured by micrometry. The results indicated that the egg size of D. nihonkaiense (total number of eggs measured, 320) was widely variable according to individual specimens, 54-76 µm long (mean 64) and 35-58 µm wide (mean 45), with a length-width ratio of 1.32-1.70 (mean 1.46). The worm showing the smallest egg size had a length range of 54-62 µm, whereas the one showing the largest egg size had a length range of 68-76 µm. The two ranges did not overlap, and a similar pattern was observed for the egg width. Mapping of each egg size (n = 320) showed a wide variation in length and width. The widely variable egg size of D. nihonkaiense cannot be used for specific diagnosis of diphyllobothriid tapeworm infections in human patients.

Diphyllobothrium nihonkaiense infections in a family.

Diphyllobothrium latum and Diphyllobothrium nihonkaiense are morphologically similar to each other, and only genetic method can differentiate clearly between the 2 species. A strobila of diphyllobothriid tapeworm discharged from a 7-year-old boy was analyzed to identify the species by mitochondrial cytochrome c oxidase subunit 1 (cox1) gene sequencing. He and his family (total 4 persons) ate slices of 3 kinds of raw fish 16 days before visiting our outpatient clinic. All family members complained of abdominal pain and watery diarrhea. They all expelled tapeworm strobilae in their stools. They were treated with a single oral dose of praziquantel and then complained of no more symptoms. The cox1 gene sequencing of the strobila from the boy revealed 99.9% (687/688 bp) similarity with D. nihonkaiense and only 93.2% (641/688 bp) similarity with D. latum. Thus, we assigned this tapeworm as D. nihonkaiense. This is the first report of D. nihonkaiense infection in a family in Korea, and this report includes the 8th pediatric case in Korea. The current report is meaningful because D. nihonkaiense infection within a family is rare.

Denali Inferior Vena Cava Filter Retrieval: Complications and Success Rates.

Purpose: The present study was to evaluate the outcomes of Denali filter retrieval. Materials and Methods: We retrospectively reviewed 143 patients who received Denali filter insertion from September 2015 to April 2020. Ninety-seven patients who required removal of the filters were include in this study. Filters were retrieved with either standard or advanced techniques. Venography before and after retrieval was obtained to evaluate technical success, complications and duration of filter insertion. Results: All 97 filters were retrieved successfully without complications. Ninety-two (94.8%) were retrieved with standard technique and 5 filters (5.2%) required the advanced technique. There were two cases with a filter angle greater than 15 degrees. Inferior vena cava penetration was shown in 17 patients (17.5%) on venography but was not associated with contrast media extravasation after filter removal. Conclusion: The Denali filter showed a high rate of successful retrieval without complications. This study adds value to previous studies and trials showing that the Denali filter is a reliable and safe filter that can potentially improve retrieval rates, with increasing use of this device.

The role of direct contact in forming peace-oriented international relations of a divided country: Focusing on the division of the Korean Peninsula.

BACKGROUND: The division of the Korean peninsula involved many neighbouring countries in the Korean War. The relations with those countries have since been reorganised due to active exchange. This study examined how the quantity and quality of contact with traditional alliance (US and Japan) and strategic partner (China and Russia) countries affected their national images. METHODS: To this end, this study analyzed the relation with the national image by measuring the quantity and quality of contact of an individual with each country. The quantity of contact included an evaluation of the individual's subjective amount of contact, contact path, and contact status, and the quality of contact was measured as an evaluation for the pleasure, competitiveness, intimacy, spontaneity, and necessity when contacting each country's culture. A total of 387 participants were divided into two groups based on the presence of direct contact and the quantity and quality of their contact and national images were examined. The participants were followed by a completion of the self-questionnaires including the Culture Experience Questionnaire, National Image Questionnaire, and demographic information questionnaire. RESULTS: The results of this study are as follow: first, regardless of the type of country, the national image was highly correlated with the degree of subjective contact evaluated by individuals, but there was a weak tendency with contact quality. Second, there was no significant interaction between the country type and contact status for national image, however, different national images for each country were detected. In other word, for contact quantity, contact groups showed more positive national images compared to non-contact groups in Russia, but not Japan, China, and the US. For contact quality, the positive contact experience group showed more positive national images compared to the negative contact experience group, but only in traditional alliance countries. CONCLUSION: This study highlights the importance of implementing different strategies for countries to maintain peaceful international relations.

Alteration of mitochondrial homeostasis is an early event in a C. elegans model of human tauopathy.

Tauopathies are a group of progressive neurodegenerative disorders characterized by the presence of insoluble intracellular tau filaments in the brain. Evidence suggests that there is a tight connection between mitochondrial dysfunction and tauopathies, including Alzheimer's disease. However, whether mitochondrial dysfunction occurs prior to the detection of tau aggregates in tauopathies remains elusive. Here, we utilized transgenic nematodes expressing the full length of wild type tau in neuronal cells and monitored mitochondrial morphology alterations over time. Although tau-expressing nematodes did not accumulate detectable levels of tau aggregates during larval stages, they displayed increased mitochondrial damage and locomotion defects compared to the control worms. Chelating calcium restored mitochondrial activity and improved motility in the tau-expressing larvae suggesting a link between mitochondrial damage, calcium homeostasis and neuronal impairment in these animals. Our findings suggest that defective mitochondrial function is an early pathogenic event of tauopathies, taking place before tau aggregation and undermining neuronal homeostasis and organismal fitness. Understanding the molecular mechanisms causing mitochondrial dysfunction early in tauopathy will be of significant clinical and therapeutic value and merits further investigation.

Unique Ultrasonographic Findings of Isolated IgG4-Related Lymphadenopathy.

IgG4-related disease is a rare immune-mediated disease that can involve many organs in the body. The lymph node is also where IgG4-related diseases occur, but its histological structure is different from that of other organs. For this reason, pathologists have difficulty diagnosing IgG4-related lymphadenopathy. If there were specific imaging findings of IgG4-related lymphadenopathy, it would be of great help to pathologists. A 64-year-old male visited our hospital with right ankle pain. On physical examination, the right lower extremity showed severe swelling with wound dehiscence, and infection was suspected. On CT (128-MDCT, Somatom Definition Flash, Siemens Healthcare) taken at the lower extremity, multiple enlarged lymph nodes were incidentally noted in the right inguinal area. On ultrasonography, a "starry night sign" resembling hyperechoic follicles was observed in the enlarged lymph node. A core needle biopsy was performed, and IgG4-related lymphadenopathy was diagnosed. Laboratory examination showed hypergammaglobulinemia with marked elevated serum IgG4, corresponding to IgG4-related disease. Chest and abdominal imaging were evaluated, but there was no extranodal IgG4-related disease. IgG4-related lymphadenopathy showed a very unique ultrasonography imaging finding. The cortex was filled with diffusely scattered hyperechoic foci and some bright foci gathered to form a follicle. This imaging finding may help diagnose IgG4-related lymphadenopathy.

Korean ginseng extract ameliorates abnormal immune response through the regulation of inflammatory constituents in Sprague Dawley rat subjected to environmental heat stress.

BACKGROUND: Increases in the average global temperature cause heat stress-induced disorders by disrupting homeostasis. Excessive heat stress triggers an imbalance in the immune system; thus protection against heat stress is important to maintain immune homeostasis. Korean ginseng (Panax ginseng Meyer) has been used as a herbal medicine and displays beneficial biological properties. METHODS: We investigated the protective effects of Korean ginseng extracts (KGEs) against heat stress in a rat model. Following acclimatization for 1 week, rats were housed at room temperature for 2 weeks and then exposed to heat stress (40°C/2 h/day) for 4 weeks. Rats were treated with three KGEs from the beginning of the second week to the end of the experiment. RESULTS: Heat stress dramatically increased secretion of inflammatory factors, and this was significantly reduced in the KGE-treated groups. Levels of inflammatory factors such as heat shock protein 70, interleukin 6, inducible nitric oxide synthase, and tumor necrosis factor-alpha were increased in the spleen and muscle upon heat stress. KGEs inhibited these increases by down-regulating heat shock protein 70 and the associated nuclear factor-κB and mitogen-activated protein kinase signaling pathways. Consequently, KGEs suppressed activation of T-cells and B-cells. CONCLUSION: KGEs suppress the immune response upon heat stress and decrease the production of inflammatory cytokines in muscle and spleen. We suggest that KGEs protect against heat stress by inhibiting inflammation and maintaining immune homeostasis.

Ginsenoside Rg5 prevents apoptosis by modulating heme-oxygenase-1/nuclear factor E2-related factor 2 signaling and alters the expression of cognitive impairment-associated genes in thermal stress-exposed HT22 cells.

Our results suggested that thermal stress can lead to activation of hippocampal cell damage and reduction of memory-associated molecules in HT22 cells. These findings also provide a part of molecular rationale for the role of ginsenoside Rg5 as a potent cognitive impairment preventive compound in blocking the initiation of hippocampal damage.

DNA Strand Breaks in Mitotic Germ Cells of Caenorhabditis elegans Evaluated by Comet Assay.

DNA damage responses are important for the maintenance of genome stability and the survival of organisms. Such responses are activated in the presence of DNA damage and lead to cell cycle arrest, apoptosis, and DNA repair. In Caenorhabditis elegans, double-strand breaks induced by DNA damaging agents have been detected indirectly by antibodies against DSB recognizing proteins. In this study we used a comet assay to detect DNA strand breaks and to measure the elimination of DNA strand breaks in mitotic germline nuclei of C. elegans. We found that C. elegans brc-1 mutants were more sensitive to ionizing radiation and camptothecin than the N2 wild-type strain and repaired DNA strand breaks less efficiently than N2. This study is the first demonstration of direct measurement of DNA strand breaks in mitotic germline nuclei of C. elegans. This newly developed assay can be applied to detect DNA strand breaks in different C. elegans mutants that are sensitive to DNA damaging agents.

The Caenorhabditis elegans Werner syndrome protein participates in DNA damage checkpoint and DNA repair in response to CPT-induced double-strand breaks.

The RecQ helicases play roles in maintenance of genomic stability in species ranging from Escherichia coli to humans and interact with proteins involved in DNA metabolic pathways such as DNA repair, recombination, and replication. Our previous studies found that the Caenorhabditis elegans WRN-1 RecQ protein (a human WRN ortholog) exhibits ATP-dependent 3'-5' helicase activity and that the WRN-1 helicase is stimulated by RPA-1 on a long forked DNA duplex. However, the role of WRN-1 in response to S-phase associated with DSBs is unclear. We found that WRN-1 is involved in the checkpoint response to DSBs after CPT, inducing cell cycle arrest, is recruited to DSBs by RPA-1 and functions upstream of ATL-1 and ATM-1 for CHK-1 phosphorylation in the S-phase checkpoint. In addition, WRN-1 and RPA-1 recruitments to the DSBs require MRE-11, suggesting that DSB processing controlled by MRE-11 is important for WRN-1 at DSBs. The repair of CPT-induced DSBs is greatly reduced in the absence of WRN-1. These observations suggest that WRN-1 functions downstream of RPA-1 and upstream of CHK-1 in the DSB checkpoint pathway and is also required for the repair of DSB.