• Development and Reproduction
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• v.21 no.3
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• pp.317-325
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• 2017

Direct communication between neighboring cells through connexin (Cx)-based gap junction is a crucial biological manner to regulate functions of a tissue consisting of multi-cell types. The present research evaluated expressional changes of Cx isoforms in the caput epididymis of adult rat exposed to estradiol benzoate (EB) or flutamide (Flu) at the early postnatal age. A single subcutaneous administration of EB at a low-dose [$0.015{\mu}g/kg$ body weight (BW)] or a high-dose ($1.5{\mu}g/kg\;BW$) or Flu at a low-dose ($500{\mu}g/kg\;BW$) or a high-dose (5 mg/kg BW) was performed to an animal at 1 week of age. Quantitative real-time PCR analysis was employed to determine expressional changes of Cx isoforms. The transcript levels of Cxs30.3 and 37 were decreased by a low-dose EB treatment, while decreases of Cxs31, 31.1, 32, 40, and 45 transcript levels were observed with a low-dose EB treatment. The treatment of a high-dose EB resulted in expressional reduction of Cxs30.3, 31, 31.1, 37, 40, 43, and 45. The Flu treatment at a low dose caused increases of Cxs26, 37, and 40 transcript levels but decreases of Cxs31.1, 43, and 45 transcript levels. Increases of Cxs30.3, 31, 37, and 40 mRNA amounts were induced by a high-dose Flu treatment. However, exposure to a high-dose Flu produced expressional decreases of Cxs31.1, 32, and 43 in the adult caput epididymis. These observations suggest that exposure to EB or Flu at the neonatal period could lead to aberrant expression of Cx isoforms in the adult caput epididymis.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.335-335
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• 1994

Possibility whether lead ingestion can cause selective toxicity to central serotonergic nervous system in rats was tested. Three groups of wistar rats; 1)Control, 2) Low dose and 3) High dose groups, were prepared. In prenatally lead-exposed rats, until parturition from dams, rat pups were intoxicated via placenta of mother rats having received drinking water containing either 0%(control ), 0.05%(low dose) or 0.2%(high dose) of lead acetate respectively, In postnatally lead-exposed rats, right after parturition from dams rat pups received drinking water containing either 0％ (control), 0.05%(low dose) or 0.2％(high dose) of lead acetate. At 2, 4, 6 and 8 weeks of age, tryptophan hydroxylase (TPH) activity and Na$\^$+//K$\^$+/-ATPase activity were measured in 4 areas of rat brain; Telencephalon, Diencephalon, Midbrain and Pons/Medulla. TPH activities were assayed by modified method of Beevers et al. (1983) using L-(5-$^3$H)-tryptophan as substrate. TPH activity was determined as a criterion of lead poisoning to central serotonergic nervous system and Na$\^$+//K$\^$+/-ATPase activity as a criterion of non specific lead poisoning to any kinds of tissues. Selective toxicity of lead poisoning to central serotonergic nervous system was evaluated by the changes of TPH activities without concomitant changes of Na$\^$+//K$\^$+/-ATPase activities. In prenatally lead-exposed rats. this selectivity was found in Telencephalon (2 weeks of age), Diencephalon/Midbrain (2 weeks of age), Midbrain (4 and 6 weeks of age), Pons/Medulla (2, 4 and 6 weeks of age) In rats exposed to low dose of lead and Pons/Medulla (2 weeks of age) to high dose of lead. In postnatal Iy lead-exposed rats, this selectivity was found in Telencephalon (8 weeks of age), Diencephalon(8 weeks of age), Pons/Medulla (6 and 8 weeks of age) in rats exposed to low dose of lead and Pons/Medulla (8 weeks of age) to high dose of lead. These results suggest that lead poisoning may exhibit selective toxicity to central serotonergic nervous system.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.524-528
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• 2001

The measurement of radiation response using simple and informative techniques would be of great value in studying the genetic risk following occupational, therapeutic, or accidental exposure to radiation. When patients receive radiation therapy, many suffer from side effects. Since each patient receives a different dose due to different physical conditions, it is important to measure the exact dose of radiation received by each patient to lessen the side effects. Even though several biological dosimetric systems have already been developed, there is no ideal system that can satisfy all the criteria for an idean dosimetric system, especially for low-dose radiation as used in radiation therapy. In this study, an SOS Chromotest of E. coli PQ37 was evaluated as a novel dosimeter for low-dose gamma-rays. E. coli PQ37 was originally developed to screen chemical mutagens using the SOS Chromotest-a colorimtric assay, based on the induction of ${\beta}$-galactosidase ue to DNA damage. The survival fraction of E. coli PQ37 decreased dose-dependently with an increasing dose of cobalt-60 gamma-rays. Also, a good linear correlation was found between the biological damage revealed by the ${\beta}$-galactosidase expression and the doses of gamma-rays. The expression of ${\beta}$-galactosidase activity that responded to low-dose radiation under 1 Gy was $Y=0.404+(0.089{\pm}0.3)D+(-0.018{\pm}0.16)D^2$ (Y, absorbance at 420 nm; D, Dose of irradiation) as calculated using Graph Pad In Plot and Excel. When a rabbit was fed with capsules containing an agar block embdded with E. coli PQ37 showed a linear response to the radiation doses. Accordingly, the results confirm that E. coli PQ37 can be used as a sensitive biological dosimeter fro cobalt-60 gamma-rays. To the best of our knowledge, this is the first time that a bacterium has been used as a biological dosimeter, especially for low-dose radiation.

• Journal of Radiation Protection and Research
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• v.21 no.2
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• pp.99-105
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• 1996

After high-dose irradiation(8 Gy). the viability of lymphocyte with a prior low-dose irradiation was 3.7-fold higher than that without a prior low-dose irradiation The viability could be increased by the reduction of oxygen radicals or the removal of damaged molecules-DNA, protein. lipid membrane. or the removal of damaged cells. In this paper. we studied the radioresistance mechanism in lymphocytes and lymphoma cells by examining the activities of radical scavengers(catalase. peroxidase, superoxide dismutase, and glucose-6-phosphate dehydrogenase), and a radical protector(glutathione). Different enzymes were induced in lymphocyte and lymphoma with low-dose irradiation. The activity of peroxidase increased most(133.3%) in lymphoma while the enzymes increased most in lymphocyte were superoxide dismutase (138.5%), glucose-6-phosphate dehydrogenase (122.4%) and glutathione(120.8%). The activities of these enzymes were highest when the interval was 7 hours between low-dose and high-dose irradiation.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1033-1039
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• 2023

Low-dose chest CT, which is used as a lung screening test, also includes information on coronary artery calcification within the scan range. The purpose of this study was to investigate the usefulness of determining coronary artery calcification using Low-dose chest CT. Those who underwent low-dose chest CT and coronary artery calcification score CT on the same day were eligible. Coronary artery calcium score CT results were divided into 4 groups (Low: 1〈CACS〈10, Mild: 10〈CACS〈100, Moderate: 100〈CACS〈400, High: 400〈CACS) by referring to the Coronary artery calcium score categories and risks. After selecting 30 people each group, five radiotechnologists with more than 15 years of experience in coronary artery calcium measurement retrospectively analyzed the presence or absence of coronary artery calcification in low-dose chest CT images. The results of the five observers' uniform interpretation of the low-dose chest CT image were consistent with the coronary artery calcium score CT results in Low group: 56%, Mild group: 96.6%, Moderate group: 100%, and High group: 100%. appeared. In the Low group, all 5 observers observed calcification in 17 out of 30 cases, and in 7 cases all 5 observers decided that calcification could not be identified. Coronary artery calcification could be observed in 100% of asymptomatic adults with a calcium score of 15 or higher in low-dose chest CT scans. The minimum calcium score that can be identified is 1, and it was found that even very small calcifications can be identified when the subject's body size is small or the scan is performed at a time when heart movement is minimal.

• Imaging Science in Dentistry
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• v.34 no.3
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• pp.137-144
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• 2004

Purpose: To investigate the effects of low dose irradiation on the calcium content and calcific nodule formation of the MC3T3-El osteoblastic cell line. Materials and Methods: Cells were irradiated with a single dose of 0.2, 0.4 and 0.6 Gy at a dose rate of 5.38 Gy/min using Cs-137 irradiator. After irradiation, the calcium content and calcific nodule formation were examined on the 1st, 2nd, 3rd and 4th week. Results: We did not find any significant difference of total calcium content after irradiation of 0.2, 0.4 and 0.6 Gy when compared with the unirradiated control group. There was no significant difference of total calcium content between 0.2, 0.4 and 0.6 Gy irradiated groups. We found an increased tendency of the calcific nodule formation after irradiation of 0.2, 0.4 and 0.6 Gy when compared with the unirradiated control group without significant difference of calcific nodule formation between 0.2, 0.4 and 0.6 Gy irradiated groups. Conclusion : The results showed an increased tendency of the calcific nodule formation after low dose irradiation. However, this tendency did not increase with the increase of irradiation dose.

• The Korean Journal of Pain
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• v.24 no.4
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• pp.199-204
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• 2011

Background: Although many clinicians know about the reducing effects of the pulsed and low-dose modes for fluoroscopic radiation when performing interventional procedures, few studies have quantified the reduction of radiation-absorbed doses (RADs). The aim of this study is to compare how much the RADs from a fluoroscopy are reduced according to the C-arm fluoroscopic modes used. Methods: We measured the RADs in the C-arm fluoroscopic modes including 'conventional mode', 'pulsed mode', 'low-dose mode', and 'pulsed + low-dose mode'. Clinical imaging conditions were simulated using a lead apron instead of a patient. According to each mode, one experimenter radiographed the lead apron, which was on the table, consecutively 5 times on the AP views. We regarded this as one set and a total of 10 sets were done according to each mode. Cumulative exposure time, RADs, peak X-ray energy, and current, which were viewed on the monitor, were recorded. Results: Pulsed, low-dose, and pulsed + low-dose modes showed significantly decreased RADs by 32%, 57%, and 83% compared to the conventional mode. The mean cumulative exposure time was significantly lower in the pulsed and pulsed + low-dose modes than in the conventional mode. All modes had pretty much the same peak X-ray energy. The mean current was significantly lower in the low-dose and pulsed + low-dose modes than in the conventional mode. Conclusions: The use of the pulsed and low-dose modes together significantly reduced the RADs compared to the conventional mode. Therefore, the proper use of the fluoroscopy and its C-arm modes will reduce the radiation exposure of patients and clinicians.

• Development and Reproduction
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• v.20 no.4
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• pp.349-357
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• 2016

The present research was chiefly designed to determine the effect of the treatment of estrogenic agonist, estradiol benzoate (EB), or antiandrogenic compound, flutamide (Flu), at the weaning age on the expression of connexin (Cx) isoforms in the caudal epididymis of adult male rat. Animals were subcutaneously administrated with a single shot of either EB at a low-dose ($0.015{\mu}g$ of EB/kg body weight (BW)) or a high-dose ($1.5{\mu}g$ of EB/kg BW) or Flu at a low-dose ($500{\mu}g$ of EB/kg BW) or a high-dose (5 mg of EB/kg BW). Expressional changes of Cx isoforms in the adult caudal epididymis were examined by quantitative real-time PCR analysis. The treatment of a low-dose EB caused significant increases of Cx30.3, Cx31, Cx32, and Cx43 transcript levels but reduction of Cx31.1, Cx37, and Cx45 expression. Exposure to a high-dose EB resulted in very close responses observed in a low-dose EB treatment, except no significant expressional change of Cx37 and a significant induction of Cx40. Expression of all Cx isoforms, except Cx45, was significantly increased by a low-dose Flu treatment. Expressional increases of all Cx isoforms were detected by a high-dose Flu treatment. The current study demonstrates that a single exposure to estrogenic or antiandrogenic compound during the early postnatal developmental period is sufficient to disrupt normal expression of Cx isoforms in the adult caudal epididymis.

• Clinical and Experimental Pediatrics
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• v.60 no.1
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• pp.24-29
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• 2017

Purpose: Previously, Kawasaki disease (KD) treatment with low-dose aspirin was administered for 6-8 weeks after the acute phase. However, inflammatory marker levels normalize before 6-8 weeks. In this study, we aimed to investigate the clinical outcome of short-term low-dose aspirin treatment based on inflammatory and thrombotic marker levels. Methods: We performed a retrospective review of the medical records of patients with KD who were hospitalized at Chungnam National University Hospital between September 2012 and May 2014. When fever subsided, low-dose aspirin treatment was started. Inflammatory (white blood cell count, erythrocyte sedimentation rate, and C-reactive protein) and thrombotic markers (D-dimer) were monitored at follow-ups conducted in 1- to 2-week intervals. The low-dose aspirin administration was terminated when both markers were normalized and no cardiovascular complications were observed. Results: Eighty-four patients with KD (complete KD, n=49; incomplete KD, n=35) were enrolled. The inflammatory and thrombotic marker levels were normalized within 3-4 weeks on average. At the beginning the low-dose aspirin treatment, 9 patients had coronary artery lesions but 75 did not. When the low-dose aspirin administration was terminated at the time the inflammatory marker levels were normalized, no new CALs developed during the follow-up at 6-8 weeks. Conclusion: Most of the inflammatory marker levels were normalized within 3-4 weeks after the acute phase of KD. New cardiovascular complications did not develop during the course of the short-term aspirin treatment based on the inflammatory marker levels, clinical findings, and echocardiography.

• Archives of Craniofacial Surgery
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• v.18 no.3
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• pp.162-165
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• 2017

Background: It is controversial issue that heparin decreases thrombosis for microsurgical anastomosis, and its effective role is under discussion. This study is for proving whether low-dose heparin is preventing thrombosis in free flap reconstruction. Methods: Through chart reviews of 134 patients, using low-dose heparin for free tissue transfer from 2011 to 2016, retrospective analysis was performed. 33 patients received low-dose heparin therapy after surgery. And 101 patients received no-heparin therapy. Complications included flap necrosis, hematoma formation, dehiscence and infection. Results: In no-heparin therapy group, comparing the flap necrosis revealed 16 cases (15.84%). And, flap necrosis was 6 cases (18.18%) in low-dose heparin therapy group. The statistical analysis of flap necrosis rate showed no significant difference (p=0.75). The results showed that there was no significant difference of flap necrosis rate between two groups. Conclusion: In this study, patients in the low-dose heparin group had no significantly lower rates of flap failure compared with no-heparin group. This suggests that low-dose heparin may not prevent thrombosis and subsequent flap failure to a significant extent.