• 제목/요약/키워드: low dose effect

검색결과 1,025건 처리시간 0.024초

Pretreatment of Low Dose Radiation Reduces Radiation-Induced Apoptosis in Mouse Lymphoma (EL4) cells

  • Kim, Jeong-Hee;Hyun, Soo-Jin;Yoon, Moon-Young;Jioon, Young-Hoon;Cho, Chul-Koo;Yoo, Seong-Yul
    • Archives of Pharmacal Research
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    • 제20권3호
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    • pp.212-217
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    • 1997
  • Induction of an adaptive response to ionizing radiation in mouse lymphoma (EL4) cells was studied by using cell survival fraction and apoptotic nucleosomal DNA fragmentation as biological end points. Cells in early log phase were pre-exposed to low dose of ${\gamma}$-rays (0.01 Gy) 4 or 20 hrs prior to high dose ${\gamma}$-ray (4, 8 and 12 Gy for cell survival fraction analysis; 8 Gy for DNA fragmentation analysis) irradiation. Then cell survival fractions and the extent of DNA fragmentation were measured. Significant adaptive response, increase in cell survival fraction and decrease in the extent of DNA fragmentation were induced when low and high dose .gamma.-ray irradiation time interval was 4 hr. Addition of protein or RNA synthesis inhibitor, cycloheximide or 5,6-dichloro-1-.betha.-d-ribofuranosylbenzimidazole (DRFB), respectively during adaptation period, the period from low dose ${\gamma}$-ray irradiation to high dose ${\gamma}$-ray irradiation, was able to inhibit the induction of adaptive response, which is the reduction of the extent DNA fragmentation in irradiated EL4 cells. These data suggest that the induction of adaptive response to ionizing radiation in EL4 cells required both protein and RNA synthesis.

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경막외 몰핀 단독 투여와 국소마취제 혼주가 술후 진통 효과에 미치는 영향 (The Effect of Low Dose Bupivacaine on Epidural Morphine Analgesia for Postoperative Pian)

  • 하한수;박영철;김해규;백승완;정규섭
    • The Korean Journal of Pain
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    • 제7권2호
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    • pp.188-192
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    • 1994
  • Recently, epidural morphine has been administrated to decrease patients' systemic stress responses such as: suffers, endocrine responses and impairment of pulmonary function, etc. Epidural morphine provided excellent analgesic effect, but incomplete sensory blockade as compared to epidural local anesthetics, which has sympathetic blockade effect and tachyphylaxis. Therefore, the authors surmised that low dose bupivacaine on low dose epidural morphine improved postoperative pain with greater sensory analgesia than epidural morphine alone. The effect of low dose bupivacaine on epidural morphine analgesia for postoperative pain was evaluated in seventy patients. They were physical status I-III by ASA classification. Patients were randomly divided into 2 groups and they were administrated morphine 2.5 mg only (group I), morphine 2.5 mg plus 0.125% bupivacaine (group II) through epidural catheter 1 hour before the end of the operation. During postoperative second days, their analgesic effects were evaluated by visual analogue scale (0-10). Side effects were also evaluated. The results were as follows, 1) On the day of the operation, VAS score showed significant differences between two groups (morphine group $3.20{\pm}0.16$, morphine plus bupivacaine group $2.77{\pm}0.08$; p < 0.05). 2) On the postoperative and second day, there were no statistical differences between the groups according to VAS score. 3) The incidence of pruritus, nausea, and vomiting were no differences in both groups. 4) None of the patients showed objective sedation or a low respiratory rate (< 10 bpm). We concluded that epidural administration of low dose bupivacaine on the epidural morphine analgesia was an effective method to decrease postoperative pain with little change in frequencies of side effects compared to epidural morphine alone.

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Radiation Effects on the Power MOSFET for Space Applications

  • Lho, Young-Hwan;Kim, Ki-Yup
    • ETRI Journal
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    • 제27권4호
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    • pp.449-452
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    • 2005
  • The electrical characteristics of solid state devices such as the bipolar junction transistor (BJT), metal-oxide semiconductor field-effect transistor (MOSFET), and other active devices are altered by impinging photon radiation and temperature in the space environment. In this paper, the threshold voltage, the breakdown voltage, and the on-resistance for two kinds of MOSFETs (200 V and 100 V of $V_{DSS}$) are tested for ${\gamma}-irradiation$ and compared with the electrical specifications under the pre- and post-irradiation low dose rates of 4.97 and 9.55 rad/s as well as at a maximum total dose of 30 krad. In our experiment, the ${\gamma}-radiation$ facility using a low dose, available at Korea Atomic Energy Research Institute (KAERI), has been applied on two commercially available International Rectifier (IR) products, IRFP250 and IRF540.

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저선량 방사선이 고추의 초기생육과 후속고선량 내성에 미치는 영향 (Effects of Low Dose Gamma Radiation on the Early Growth of Pepper and the Resistance to Subsequent High Dose of Radiation)

  • 김재성;백명화;김동희;이영근;이영복
    • 환경생물
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    • 제19권1호
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    • pp.71-77
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    • 2001
  • 저선량 방사선 조사한 고추 2품종, 조광고추와 조흥고추의 종자 발아율과 초기생육 및 고추 유식물체의 후속 고선량에 대한 내성 변화를 알아보고자 저선량 0, 4, 8, 20, 50 Gy를 조사하여 재배한 고추 유식물체에 ${\gamma}$선 50 Gy와 100 Gy를 조사한 후 생육상황을 관찰하였다. 저선량 조사한 고추 유식물체의 초기생육 촉진과 후속고선량 내성은 품종에 따라 달랐는데, 조광고추보다 조홍고추 품종에서 뚜렷한 증가효과를 나타냈고 발아율과 초기생육촉진은 4, 8, 20 Gy 조사구에서 효과적이었다. 조홍고추 유식물체의 후속고선량에 대한 내성은 사전 저선량 조사에 의해 크게 증가되었는데 특히 4Gy조사구에서 효과가 가장 뚜렷하였으며 후속고선량에 대해 내성이 증진된 고추 유식물체중의 carotenoid와 단백질 함량 및 CAT활성은 4 Gy와 8 Gy 조사구에서 높았다.

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Can ultra-low-dose computed tomography reliably diagnose and classify maxillofacial fractures in the clinical routine?

  • Gerlig Widmann;Marcel Dangl;Elisa Lutz;Bernhard Fleckenstein;Vincent Offermanns;Eva-Maria Gassner;Wolfgang Puelacher;Lukas Salbrechter
    • Imaging Science in Dentistry
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    • 제53권1호
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    • pp.69-75
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    • 2023
  • Purpose: Maxillofacial trauma predominantly affects young adults between 20 and 40 years of age. Although radioprotection is a legal requirement, the significant potential of dose reduction in computed tomography (CT) is still underused in the clinical routine. The objective of this study was to evaluate whether maxillofacial fractures can be reliably detected and classified using ultra-low-dose CT. Materials and Methods: CT images of 123 clinical cases with maxillofacial fractures were classified by two readers using the AOCOIAC software and compared with the corresponding results from post-treatment images. In group 1, consisting of 97 patients with isolated facial trauma, pre-treatment CT images at different dose levels (volumetric computed tomography dose index: ultra-low dose, 2.6 mGy; low dose, <10 mGy; and regular dose, <20 mGy) were compared with post-treatment cone-beam computed tomography (CBCT). In group 2, consisting of 31 patients with complex midface fractures, pre-treatment shock room CT images were compared with post-treatment CT at different dose levels or CBCT. All images were presented in random order and classified by 2 readers blinded to the clinical results. All cases with an unequal classification were re-evaluated. Results: In both groups, ultra-low-dose CT had no clinically relevant effect on fracture classification. Fourteen cases in group 2 showed minor differences in the classification code, which were no longer obvious after comparing the images directly to each other. Conclusion: Ultra-low-dose CT images allowed the correct diagnosis and classification of maxillofacial fractures. These results might lead to a substantial reconsideration of current reference dose levels.

Studies on Digitalis Receptor Desensitization in Rat Ventricle

  • Lee, Shin-Woong-;Jang, Tae-Soo
    • 한국응용약물학회:학술대회논문집
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    • 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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    • pp.301-301
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    • 1994
  • $^3$H〕Ouabain binding parameters(K$\_$D/ and B$\_$max/,) in homogenates prepared fpom control rat ventricular strip and Langendorff preparations which were not previously exposed to ouabain were compared to those in homogenates from ventricular strip and Langendorff preparations that had been first exposed to a complete ouabain dose-response curve(10$\^$-7/M to 10$\^$-4/ M). In rat ventricular strips and Langendorff perfused rat heart preparations, cumulative dose-response cruves of ouabain revealed biphasic positive inotropic effects, a "low-dose" and a "high-dose" effect with ED$\_$50/ values of 0.5${\mu}$M and 35${\mu}$M ouabain, respectively- The "low-dose" effect in rat ventricular strips disappeared or was diminished significantly when the ouabain dose-response curve wag repeated after the washout of the effects of the first curve, whereas the maximal "high-dose" effect was identical in both exposures to oubain. However, there was no change in the "low-dose" effects in both sets of the Langendorff perfused hearts. The contractile activity of the pre-exposed strips did not indicate the presence of residual ouabain since their basal contractile force was decreased 10% compared to initial control. 〔$^3$H〕Ouabain binding parameters, K$\_$D/ and B$\_$max/, were not changed comparing homogenate of control ventricular strips with that of strips pre-exposed to ouabain. These results suggest that digitalis receptor desensitization in the rat ventricular strip may due to the change of post-receptor events induced by ouabain binding to a high affinity site(${\alpha}$$_2$ isoform).

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저선량 ${\gamma}$선 조사가 대두 식물체의 방사선 감수성에 미치는 영향 (Effects of Low Dose ${\gamma}$ Radiation on the Radiosensitivity of Soybean(Glycine max L.) Plant)

  • 김재성;채성기;백명화;김동희
    • 한국환경농학회지
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    • 제19권4호
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    • pp.324-327
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    • 2000
  • 저선량 조사한 대두종자의 초기생육과 대두 유식물체의 후속고선량에 대한 방사선 감수성 변화를 알아보고자 저선량 0, 4, 8, 12, 20 Gy를 조사하여 재배한 대두 유식물체에 ${\gamma}$선 50, 100, 200 Gy를 조사한 후 생육상황을 관찰하였다. 저선량 조사에 의해 대두 신규종자의 발아율 증가효과는 없었으나 작물 생장 증대효과는 있었으며 저선량 8 Gy 조사구가 가장 효과적이었다. 대두유식물체의 고선량 방사선에 의한 생육장해는 사전 저선량조사에 의해 크게 감소되었으며 저선량 조사에 의한 고선량 방사선 저항성 증가는 8 Gy와 20 Gy조사에서 가장 효과적이었다.

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옥수수 생육에 미치는 저선량 감마선 조사효과 (Influence of Low Dose Gamma Radiation on the Growth of Maize(Zea mays L.) Varieties)

  • 김재성;이영근;박홍숙;백명화;김동희
    • 한국환경농학회지
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    • 제19권4호
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    • pp.328-331
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    • 2000
  • 국내에서 재배중인 옥수수 재래종 (고성, 영월)품종의 종자에 저선량 ${\gamma}$선을 조사하여 초기생육과 수량에 미치는 영향을 온실과 포장실험으로 조사하였다. 저선량 방사선 조사가 옥수수 종자발아 및 초기생육에서 뚜렷한 촉진효과를 보였으나 품종별로 다소 차이가 있었으며 고성재래종은 2 Gy, 영월재래종은 12 Gy가 가장 효과적이었다. 포장생장과 수량에서도 저선량 조사에 의해 증가하는 경향을 보였는데 적정선량은 고성재래종은 8 Gy, 영월재래종은 $4{\sim}12$ Gy 범위로 나타났다.

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저선량 감마선이 땅콩 생장에 미치는 효과 (Effect of Low Dose of Gamma Radiation on the Growth of Groundnut (Arachis hypogaea L.))

  • 김재성;이은경;백명화;박홍숙;김광호
    • 환경생물
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    • 제17권3호
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    • pp.257-261
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    • 1999
  • 저선량 방사선 조사가 땅콩 “팔팔” 품종 종자의 발아율과 초기생육 및 수량에 미치는 효과를 알아보고자 ${\gamma}$선을 0.5~20.0 Gy 까지 조사하여 포장에 직파재배하였다. 땅콩 종자의 발아율은 저선량 조사에 의해 별다른 효과가 없었으나 유묘초장은 저선량 조사구에서 다소 양호하였다. 수량구성요소 중협수와 종실수 및 종자수량은 12.0 Gy 조사구에서 가장 높았으며, 대조구에 비해 각각 27%와 17% 및 19% 유의성있게 증가하였다. 100립중은 4.0 Gy 조사구가 87.2g으로 대조구의 78.3g에 비해 11%정도 증가하여 저선량 조사에 의해 땅콩 수량이 유의성있는 증가효과를 보였다.

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Dosimetric Effects of Low Dose 4D CT Using a Commercial Iterative Reconstruction on Dose Calculation in Radiation Treatment Planning: A Phantom Study

  • Kim, Hee Jung;Park, Sung Yong;Park, Young Hee;Chang, Ah Ram
    • 한국의학물리학회지:의학물리
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    • 제28권1호
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    • pp.27-32
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    • 2017
  • We investigated the effect of a commercial iterative reconstruction technique (iDose, Philips) on the image quality and the dose calculation for the treatment plan. Using the electron density phantom, the 3D CT images with five different protocols (50, 100, 200, 350 and 400 mAs) were obtained. Additionally, the acquired data was reconstructed using the iDose with level 5. A lung phantom was used to acquire the 4D CT with the default protocol as a reference and the low dose (one third of the default protocol) 4D CT using the iDose for the spine and lung plans. When applying the iDose at the same mAs, the mean HU value was changed up to 85 HU. Although the 1 SD was increased with reducing the CT dose, it was decreased up to 4 HU due to the use of iDose. When using the low dose 4D CT with iDose, the dose change relative to the reference was less than 0.5% for the target and OARs in the spine plan. It was also less than 1.1% in the lung plan. Therefore, our results suggests that this dose reduction technique is applicable to the 4D CT image acquisition for the radiation treatment planning.