FLASH radiotherapy (FLASH-RT) is an innovative approach that delivers ultra-high dose rates exceeding 40 Gy in less than a second, aiming to widen the therapeutic window by minimizing damage to normal tissue while maintaining tumor control. This review explores the advancements, mechanisms, and clinical applications of FLASH-RT across various radiation sources. Electrons have been predominantly used due to technical feasibility, but their limited penetration depth restricts clinical application. Protons, offering deeper tissue penetration, are considered promising for treating deep-seated tumors despite challenges in beam delivery. Preclinical studies demonstrate that FLASH-RT reduces normal tissue toxicity in the lung, brain, skin, intestine, and heart without compromising antitumor efficacy. The mechanisms underlying the FLASH effect may involve oxygen depletion leading to transient hypoxia, reduced DNA damage in normal tissues, and modulation of immune and inflammatory responses. However, these mechanisms are incompletely understood, and inconsistent results across studies highlight the need for further research. Initial clinical studies, including treatment of cutaneous lymphoma and bone metastases, indicate the feasibility and potential benefits of FLASH-RT in patients. Challenges for clinical implementation include technical issues in dosimetry accuracy at ultra-high dose rates, adaptations in treatment planning systems, beam delivery methods, and economic considerations due to specialized equipment requirements. Future directions will involve comprehensive preclinical studies to optimize irradiation parameters, large-scale clinical trials to establish standardized protocols, and technological advancements to overcome limitations. FLASH-RT holds the potential to revolutionize radiotherapy by reducing normal tissue toxicity and improving therapeutic outcomes, but significant research is required for real-world clinical applications.
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, In-Young Yoon, Dong Yeon Kim, Sooyoung Cho OxyMask, a novel product, has recently been used to administer oxygen postoperatively to patients who have undergone general anesthesia. This study aimed to evaluate the incidence of hypoxia in patients under general anesthesia upon arrival to the post-anesthesia care unit (PACU) using arterial blood gas analysis, and to compare the effectiveness of OxyMask with a non-rebreathing oxygen mask for oxygen administration.
We retrospectively investigated anesthesia-related data from the electronic medical records of 460 patients treated from April to November 2021. We analyzed patients aged 20 years or older who had undergone general anesthesia and whose perioperative arterial blood gas analysis results were available upon arrival to the PACU. These patients were grouped into the non-rebreathing oxygen mask (n=223) and OxyMask (n=237) groups, and statistical analysis was performed utilizing their anesthesia records.
No patients exhibited hypoxia upon arrival to the recovery room. The oxygen concentration increased after oxygen administration; its concentration during the recovery room period (Δ2 PaO2) was 10.7±42.3 and 13.9±38.5 mmHg in the non-rebreathing oxygen mask and OxyMask groups, respectively. This difference was not statistically significant. Moreover, the arterial oxygen saturation between the end of surgery and upon arrival to the PACU (Δ1 SaO2) and the arterial oxygen saturation 20 minutes after oxygen administration at the PACU (Δ2 SaO2) did not significantly differ between the groups.
OxyMask was not superior to a non-rebreathing oxygen mask in terms of the effectiveness of oxygen supply.
As the number of elderly people rises, the incidence of surgery in elderly patients would become higher. This study was undertaken to examine the changes in pulmonary gas exchange that occurs with advancing age.
Arterial blood gases were analysed in 106 elderly patients over the age of 65 and 40 adult patients(control group) during breathing of room air preoperatively. Alveolar oxygen partial pressure(PAO2), alveolar-arterial partial pressure gradient for oxygen(AaDO2), arterial/alveolar oxygen partial pressure(a/A) ratio were calculated using PaO2 and PaCO2 and PAO2 and measured the relationship between the PaO2 and age.
PaO2 declined as age increased significantly and the regression equation was PaO2=103.6-0/332×age(r=0.55). There was no significant difference in PaCO2 and PAO2 but AaDO2 increased and a/A ratio decreased significantly.
As the AaDO2 and a/A ratio were changed significantly, it is necessary for monitoring of oxygenation during perioperative periods in elderly patients.
, Soo A Oh, Kyoung-Eun Lee, Eun-Sun Yoo, Moon Young Choi, Jee-Young Ahn, Chu-Myong Seong Leukotriene B4(LTB4) is lipid mediator derived from membrane phospholipids during the process of inflammation, having many roles(ie; inducer of chemotaxis, the production of nitric oxide, transepithelial migration of neutrophil). The major activities of LTB4 include the recruitment and activation of leukocytes, suggesting that it may involve the process for transendothelial migration of nuclear cells in bone marrow environment. Reactive Oxygen Species (ROS) have a cell signaling roles that are involved in signal transduction cascades of numerous growth factor-, cytokine-, and hormone-mediated pathways, and regulate many biological systems. In this present study, we focused on the role of LTB4 and ROS on transmigration of bone marrow nuclear cells across endothelial or stromal cell monolayer.
MS-5, murine stromal cell line cells, or bEnd.3, murine microvascular cell line cells, were grown to confluence on microporous transwell membrane. Murine marrow cells were placed on top of the prepared transwell membrane. The transwells were then seated in wells containing media and LTB4 with or without pretreatment of N-acetylcysteine(NAC), an oxygen free radical scavenger, or diphenylene iodonium(DPI), an inhibitor of NADPH oxidase-like flavoproteins. Cells that migrated through the stromal or endothelial layer into the wells were assayed for transendothelial migration.
The numbers of migrated bone marrow nuclear cells through the bEnd.3 were increased by treatment of LTB4(control, 12.5±0.2%; 50nM, 22.7±0.9%; 100nM, 44.3±1.4%; 200 nM, 36.3±0.9%; p<0.05). The numbers of migrated bone marrow nuclear cells through the MS-5 were also increased by treatment of LTB4(control, 11.0±0.9%; 50nM, 25.7±0.9%; 100nM, 35.8±1.8%; 200nM, 32.1±0.9%; p<0.05). However, increasing effect of LTB4 to the transmigration of bone marrow nuclear cells through the MS-5 or bEnd.3 were inhibited by pretreatment of NAC or DPI.
Through our data, it is suggested that LTB4 could induce the transmigration of bone marrow nuclear cells and ROS might be involved on the transendothelial migration of bone marrow nuclear cells by LTB4. It would be very interesting to test the effects of LTB4 and ROS on stem cell mobilization and homing in the future.
Reactive oxygen species (ROS) such as hydrogen peroxide, superoxide anion and hydroky radicals are produced in various physiologic and pathologic conditions and involved in many cellular processes as proliferation, differentiation and apoptosis. Studies investigating the role of ROS in various cellular behaviors especially in proliferation and apoptosis have been widely conducted in many cell types but the role of ROS in nontransformed human hepatocyte differentiation has not been investigated yet. thus we were going to elucidate the roleof ROS on human hepatocyte differentiaiton using sodium butyrate (SB) induced hepatocyte differentiation model of our own establishment.
Intracellular ROS and apoptotic cell death were monitored by flowcytometry using peroxide sensitive probe (Dicholorofluorscein diacetate) and Annexin V/Propidium iodide, respectively. Urea nitrogen in culture media was measured by colorimetric methods. Ornithine transcarbamylase(OTC) and albumin trasncription was evaluated by RT-PCR.
Intracellular ROS production was increased by SB. SB induced urea production was significantly decreased with antioxidant treatment (p<0.05) and SB induced OTC and albumin transcription were also attenuated with antioxidant treatment. SB induced increase in apoptosiswas significantly inhibited by antioxidant treatment (p<0.05).
ROS produced during the process of sodium butyrate induced human hepatocyte differentiation auguments hepatoctye differentiation and apoptosis.
, Guie Yong Lee, Jong In Han, Dong Yeon Kim, Rack Kyong Chung, Jong Hak Kim, Chi Hyo Kim, Choon Hi Lee Preoxygenation is recommended in order to prevent hypoxemia with hypoventilation or apnea during induction of anesthesia. The purpose of this study was to determine the duration of preoxygenation required to achieve an end-tidal oxygen fraction(FE'O2) of 0.9 in children and adults.
In 24 healthy children and adults breathing 100% oxygen, end tidal oxygen and carbon dioxide concentration have been measured at 15 seconds interval from the start of liter per minute. The gas sampling line of the Capnomac II(Datex, Helsinki, Finland) was placed in the nasal cavity.
The study showed that all children attained an FE'O2 of 0.9 within 75s of preoxygenation, but adults had not reached an FE'O2 of 0.9 within 180s.
More oxygen wash-in would be expected in children. We suggested that at least 3 min of preoxygenation should be performed before intravenous induction of anesthesia in children.
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