Establishment of NaLuF_(4):15%Tb-based low dose X-PDT agent and its application on efficient antitumor therapy

X-ray excited photodynamic therapy(X-PDT)is the bravo answer of photodynamic therapy(PDT)for deep-seated tumors,as it employs X-ray as the irradiation source to overcome the limitation of light penetration depth.However,high X-ray irradiation dose caused organ lesions and side effects became the major barrier to X-PDT application.To address this issue,this work employed a classic-al co-precipitation reaction to synthesize NaLuF_(4):15%Tb^(3+)(NLF)with an average particle size of(23.48±0.91)nm,which was then coupled with the photosensitizer merocyanine 540(MC540)to form the X-PDT system NLF-MC540 with high production of singlet oxygen.The system could induce antitumor efficacy to about 24%in relative low dose X-ray irradiation range(0.1-0.3 Gy).In vivo,when NLF-MC540 irradiated by 0.1 Gy X-ray,the tumor inhibition percentage reached 89.5%±5.7%.The therapeutic mechanism of low dose X-PDT was found.A significant increase of neutrophils in serum was found on the third day after X-PDT.By immunohistochemical staining of tumor sections,the Ly6G^(+),CD8^(+),and CD11c^(+)cells infiltrated in the tumor microenvironment were studied.Utilizing the bilat-eral tumor model,the NLF-MC540 with 0.1 Gy X-ray irradiation could inhibit both the primary tumor and the distant tumor growth.De-tected by enzyme linked immunosorbent assay(ELISA),two cytokines IFN-γand TNF-αin serum were upregulated 7 and 6 times than negative control,respectively.Detected by enzyme linked immune spot assay(ELISPOT),the number of immune cells attributable to the IFN-γand TNF-αlevels in the group of low dose X-PDT were 14 and 6 times greater than that in the negative control group,respectively.Thus,it conclude that low dose X-PDT system could successfully upregulate the levels of immune cells,stimulate the secretion of cy-tokines(especially IFN-γand TNF-α),activate antitumor immunity,and finally inhibit colon tumor growth.

Effect of low dose laser cycloplasty on deepening anterior chamber in chronic angle-closure glaucoma

AIM:To describe the outcome of using low-dose laser cycloplasty(LCP)in chronic angle-closure glaucoma(CACG).METHODS:A retrospective case series.Medical charts of CACG patients who underwent LCP in the Eye Hospital of Wenzhou Medical University were reviewed.The main outcomes included intraocular pressure(IOP),the number of glaucoma medication,anterior segment parameters and surgery-related complications.RESULTS:A total of 7 eyes of 7 CACG patients(age 38.9±11.0y)underwent LCP with a mean follow-up of 27.1±13.7mo(range 16-48mo).Following LCP,mean IOP and glaucoma medications decreased from 26.1±6.1 mm Hg with 3.1±1.1 glaucoma medications pre-treatment to 14.9±3.1 mm Hg(P=0.027)with 0.4±1.1 glaucoma medications(P=0.001)at final follow-up.The anterior chamber depth(ACD),angle opening distance500 and trabecular-iris angle increased from 1.65±0.33 mm,0.05 mm(range 0-0.30 mm)and 5.1°(range,0-31.97°)at baseline to 1.98±0.43 mm(P=0.073),0.53 mm(range 0.42-0.91 mm,P=0.015),45.9°(range,40.2°-59.4°),(P=0.015)in the long-term follow-up,respectively.The deepening of ACD and reopening of anterior chamber angle(ACA)was observed in 6 eyes(85.7%).CONCLUSION:LCP is a promising treatment option for patients with CACG via reducing IOP and glaucoma medication without serious complications.In addition,LCP can bring a significant deepening in ACD and reopening of ACA.

Variant Wasserstein Generative Adversarial Network Applied on Low Dose CT Image Denoising

Computed Tomography(CT)images have been extensively employed in disease diagnosis and treatment,causing a huge concern over the dose of radiation to which patients are exposed.Increasing the radiation dose to get a better image may lead to the development of genetic disorders and cancer in the patients;on the other hand,decreasing it by using a Low-Dose CT(LDCT)image may cause more noise and increased artifacts,which can compromise the diagnosis.So,image reconstruction from LDCT image data is necessary to improve radiologists’judgment and confidence.This study proposed three novel models for denoising LDCT images based on Wasserstein Generative Adversarial Network(WGAN).They were incorporated with different loss functions,including Visual Geometry Group(VGG),Structural Similarity Loss(SSIM),and Structurally Sensitive Loss(SSL),to reduce noise and preserve important information on LDCT images and investigate the effect of different types of loss functions.Furthermore,experiments have been conducted on the Graphical Processing Unit(GPU)and Central Processing Unit(CPU)to compare the performance of the proposed models.The results demonstrated that images from the proposed WGAN-SSIM,WGAN-VGG-SSIM,and WGAN-VGG-SSL were denoised better than those from state-of-the-art models(WGAN,WGAN-VGG,and SMGAN)and converged to a stable equilibrium compared with WGAN and WGAN-VGG.The proposed models are effective in reducing noise,suppressing artifacts,and maintaining informative structure and texture details,especially WGAN-VGG-SSL which achieved a high peak-signalto-noise ratio(PNSR)on both GPU(26.1336)and CPU(25.8270).The average accuracy of WGAN-VGG-SSL outperformed that of the state-ofthe-art methods by 1 percent.Experiments prove that theWGAN-VGG-SSL is more stable than the other models on both GPU and CPU.

Efficacy of Low Dose Naltrexone on Pain Reduction in Chronic Pain Syndromes: A Meta Analysis

Chronic pain is a multifaceted debilitating experience often associated with significant physical and emotional burden. Low dose naltrexone (LDN) has gained attention in recent years for its potential utility in the management of fibromyalgia, irritable bowel syndrome, multiple sclerosis, and painful diabetic neuropathy. LDN’s analgesic effects have been associated with its ability to increase the production of endorphins while reducing the production of tumor necrosis factor-alpha, interleukin-6, reactive oxygen species and nitric oxide. This meta-analysis aims to systematically review and synthesize the available evidence on efficacy of LDN as an analgesic in pain syndromes, with a focus on chronic (neuro) inflammatory diseases. The goal is to provide clinicians with a more comprehensive estimate of the effectiveness of LDN as a non-opioid option for managing chronic pain and guide future research in the area. Thirteen randomized control trials, published from 1990 to 2022, were selected for the analysis that satisfied inclusion criteria. The overall effects in these studies were calculated using the standardized mean difference (SMD) between the LDN and placebo groups. We found an overall SMD of -10.77 (95% CI: -13.96 to -7.58) with a p-value of 0.002. This indicated that the LDN group experienced a statistically significant reduction in pain compared to placebo. This meta-analysis provides evidence for the potential efficacy of low dose naltrexone in reducing pain and enhancing analgesia in various pain syndromes. LDN may be a useful treatment option for patients suffering from chronic pain, particularly with fibromyalgia, multiple sclerosis, or diabetic neuropathy. However, further research is needed to confirm the efficacy and safety of low dose naltrexone for chronic pain conditions, especially with larger sample sizes, standardized dosing regimens and treatment durations.

Effective Dose Screening of Low Level Red Light in Different Cell Indexes

The low level red light irradiation dose that produced positive response on different cell indexes was selected through experiments.In fibroblast detection model,the low level red light irradiation dose that had positive response to the four indicators of mitochondrial membrane potential,ATP release,cell migration and collagen synthesis was screened.The experimental results showed that low level red light with a irradiation dose of 2 J/cm^(2) had a positive response to the above four indexes in fibroblast.The test model on fibroblast was later transferred to dermal papilla cells for further experimental verification.The results showed that low level red light with a irradiation dose of 2 J/cm^(2) also had a positive response to the four indicators of dermal papilla cells,namely,mitochondrial membrane potential,ATP release,cell proliferation rate and collagen synthesis.It is proved that the low level red light with a irradiation dose of 2 J/cm^(2) could improve the mitochondrial function,cell migration and collagen synthesis of fibroblast and dermal papilla cell,thus providing energy for cell activities,improving cell repair ability and cell anti-aging ability.

Effects of Low Dose Radiation on Tumor Apoptosis, Cell Cycle and Apoptosis-Related Protein Bcl-2 in Tumor-Bearing Mice

To study the effects of low dose radiation (LDR) on tumor apoptosis, cellcycle progression and changes of apoptosis-related protein Bcl-2 in tumor-bearing mice. Methods:Male mice of Kunming strain were implanted subcutaneously with S180 sarcoma cells in the left inguenas an in situ experimental animal model. Seven days later, the mice were subjected to 75 mGywhole-body γ-irradiation. At 24 and 48 h after the irradiation, all mice were sacrificed. The tumorsizes were measured, and tumor cell apoptosis and cell cycle progression were analyzed by flowcytometry. The expression of apoptosis-related protein Bcl-2 and the apoptotic rate of tumor cellswere observed by immunohistochemistry and electron microscopy. Results: Tumors grew significantlyslower after LDR (P 【 0.05). The tumor cells were arrested in G1 phrase and the expression of Bcl-2protein decreased at 24 h. Apoptotic rate of tumor cells was increased significantly at 48 h afterLDR (P 【 0.01). Conclusion: LDR could cause a G1-phase arrest and increase the apoptosis of tumorcells through the low level of apoptosis-related protein bcl-2 in the tumor-bearing mice. Theorganized immune function and anti-tumor ability are markedly increased after LDR. Our studyprovides practical evidence of clinical application to cancer treatment.

Interaction between Helicobacter pylori infection, nonsteroidal anti-inflammatory drugs and/or low-dose aspirin use: Old question new insights

Previous reports clearly demonstrated that Helicobacter pylori(H.pylori)infection,nonsteroidal anti-inflammatory drugs(NSAID)or low dose aspirin(ASA)use significantly and independently increased the risk for the development of peptic ulcer disease.Today,the presence of H.pylori infection associated with low dose ASA and/or NSAID use in the same patient is becoming more frequent and therefore the potential interaction between these factors and the consequences of it has important implications.Whether NSAID intake in the presence of H.pylori infection may further increase the risk of peptic ulcer carried by the presence of only one risk factor is still a matter of debate.Studies on the interaction between the two risk factors yielded conflicting data and no consensus has been reached in the last years.In addition,the interaction between H.pylori infection and low-dose ASA remains even more controversial.In real clinical practice,we can find different clinical scenarios involving these three factors associated with the presence of different gastrointestinal and cardiovascular risk factors.These huge variety of possible combinations greatly hinder the decision making process of physicians.

Involvement of Endoplasmic Reticulum Stress in Apoptosis of Testicular Cells Induced by Low-dose Radiation

Summary： The study examined the role of endoplasmic reticulum stress （ERS） and signaling pathways of inositol-requiring enzyme-1 （IRE1）, RNA-activated protein kinase-like ER kinase （PERK） and activating transcription factor-6 （ATF6） in apoptosis of mouse testicular cells treated with low-dose radiation （LDR）. In the dose-dependent experiment, the mice were treated with whole-body X-ray irradiation at different doses （25, 50, 75, 100 or 200 mGy） and sacrificed 12 h later. In the time-dependent experiment, the mice were exposed to 75 mGy X-ray irradiation and killed at different time points （3, 6, 12, 18 or 24 h）. Testicular cells were harvested for experiments. H202 and NO concentrations, and Ca2＋-ATPase activity were detected by biochemical assays, the calcium ion concentration （[Ca2＋]i） by flow cytometry using fluo-3 probe, and GRP78 mRNA and protein expressions by quantitative real-time RT-PCR （qRT-PCR） and Western blotting, respectively. The mRNA expressions of S-XBP1, JNK, caspase-12 and CHOP were measured by qRT-PCR, and the protein expressions of IREla, S-XBP1, p-PERK, p-elF2a, ATF6 p50, p-JNK, pro-caspase-12, cleaved caspase-12 and CHOP by Western blot- ting. The results showed that the concentrations of H202 and NO, the mR_NA expressions of GRP78, S-XBP1, JNK, caspase-12 and CHOP, and the protein expressions of GRP78, S-XBP1, IREla, p-PERK, p-elF2a, ATF6 p50, p-JNK, pro-caspase-12, cleaved caspase-12 and CHOP were significantly increased in a time- and dose-dependent manner after LDR. But the [Ca2]i and Ca2-ATPase activities were sig nificantly decreased in a time and dose-dependent manner. It was concluded that the ERS, regulated by IRE 1, PERK and ATF6 pathways, is involved in the apoptosis of testicular cells in LDR mice, which is associated with ERS-apoptotic signaling molecules of JNK, caspase-12 and CHOP.

Slice-wise reconstruction for low-dose cone-beam CT using a deep residual convolutional neural network

Because of the growing concern over the radiation dose delivered to patients, X-ray cone-beam CT(CBCT) imaging of low dose is of great interest. It is difficult for traditional reconstruction methods such as Feldkamp to reduce noise and keep resolution at low doses. A typical method to solve this problem is using optimizationbased methods with careful modeling of physics and additional constraints. However, it is computationally expensive and very time-consuming to reach an optimal solution. Recently, some pioneering work applying deep neural networks had some success in characterizing and removing artifacts from a low-dose data set. In this study,we incorporate imaging physics for a cone-beam CT into a residual convolutional neural network and propose a new end-to-end deep learning-based method for slice-wise reconstruction. By transferring 3D projection to a 2D problem with a noise reduction property, we can not only obtain reconstructions of high image quality, but also lower the computational complexity. The proposed network is composed of three serially connected sub-networks: a cone-to-fan transformation sub-network, a 2D analytical inversion sub-network, and an image refinement sub-network. This provides a comprehensive solution for end-to-end reconstruction for CBCT. The advantages of our method are that the network can simplify a 3D reconstruction problem to a 2D slice-wise reconstruction problem and can complete reconstruction in an end-to-end manner with the system matrix integrated into the network design. Furthermore, reconstruction can be less computationally expensive and easily parallelizable compared with iterative reconstruction methods.

Correlation between Low Tube Voltage in Dual Source CT Coronary Artery Imaging with Image Quality and Radiation Dose

The influence of low tube voltage in dual source CT（DSCT） coronary artery imaging on image quality and radiation dose and its application value in clinical practice were investigated. Totally, 300 cases of chest pain with low body mass index（BMI 〈18.5 kg/m2） subjected to DSCT coronary artery imaging were prospectively enrolled. The heart rate in all patients were greater than 65/min. The retrospective ECG gated scanning mode and simple random sampling method were used to assign the patients into groups A, B and C（n=100 each）. The patients in groups A, B and C experienced 120-, 100-, and 80-kV tube voltage imaging respectively, and the image quality was evaluated. The CT volume dose index（CTDIvol） and dose length product（DLP） were recorded, and the effective dose（ED） was calculated in each group. The image quality scores and radiation doses in groups were compared, and the influence of tube voltage on image quality and radiation dose was analyzed. The results showed that the excellent rate of image quality in groups A, B and C was 95.69%, 94.72% and 96.33% respectively with the difference being not statistically significant among the three groups（P〉0.05）. The CTDIvol values in groups A, B and C were 51.35±12.21, 21.28±7.13 and 6.34±3.34 mGy, respectively, with the difference being statistically significant（P〈0.05）. The ED values in groups A, B and C were 9.27±1.63, 4.56±2.29 and 2.29±1.69 mSv, respectively, with the difference being statistically significant（P〈0.05）. It was suggested that for the patients with low BMI, the application of DSCT coronary artery imaging with low tube voltage can obtain satisfactory image quality, and simultaneously, significantly reduce the radiation dose.

Increased Levels of p53 and PARP-1 in EL-4 Cells Probably Related with the Immune Adaptive Response Induced by Low Dose Ionizing Radiation in vitro

Objective This paper is to explore the DNA repair mechanism of immune adaptive response （AR） induced by low dose radiation （LDR）, the changes of mRNA levels and protein expressions of p53, ATM, DNA-PK catalytic subunit （DNA-PKcs） and PARP-1 genes in the LDR-induced AR in EL-4 cells. Methods The apoptosis and cell cycle progression of EL-4 cells were detected by flow cytometry in 12 h after the cells received the pre-exposure of 0.075 Gy X-rays （inductive dose, D 1） and the succeeding high dose irradiation （challenge dose, D2; 1.0, 1.5, and 2.0 Gy X-rays, respectively） with or without wortmannin （inhibitor of ATM and DNA-PK） and 3-aminobenzamid （inhibitor of PARP-1）. And the protein expressions and mRNA levels related to these genes were detected with flow cytometry and reverse transcription-polymerase chain reaction in 12 h after irradiation with D2. Results The mRNA and protein expressions of p53 and PARP-1 in EL-4 cells in the D1 ＋ D2 groups were much lower than those in the D2 groups, and those of PARP-1 in the 3-AB ＋ D2 and the 3-AB ＋ D1 ＋ D2 groups were much lower than those in the D2 and the D1 ＋ D2 groups. The percentage of apoptotic EL-4 cells in the 3-AB ＋ D1 ＋ D2 groups was much higher than that in the D1 ＋ D2 groups, that in the G0/G1 and the G2 ＋ M phases was much higher, and that in the S phase were much lower. Although the ATM and DNA-PKcs mRNA and protein expressions in wortmannin ＋ D1 ＋ D2 groups were much lower than those in the D1 ＋ D2 groups, there were no significant changes in the apoptosis and cell cycle progression between the wortmannin ＋ D1 ＋ D2 and the D1 ＋ D2 groups. Conclusion PARP-1 and p53 might play important roles in AR induced by LDR.

Low contrast medium and radiation dose for hepatic computed tomography perfusion of rabbit VX2 tumor

AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential(120 k Vp) protocol with 350 mg I/m L contrast medium and filtered back projection,and a low tube potential(80 k Vp) protocol with 270 mg I/m L contrast medium with iterative reconstruction.Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor.Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.RESULTS:A 38% reduction in contrast medium dose(360.1 ± 13.3 mg I/kg vs 583.5 ± 21.5 mg I/kg,P < 0.001) and a 73% decrease in radiation dose(1898.5 m Gy·cm vs 6951.8 m Gy·cm) were observed.Interestingly,there was a strong positive correlation in hepatic arterial perfusion(r = 0.907,P < 0.001;r = 0.879,P < 0.001),hepatic portal perfusion(r = 0.819,P = 0.002;r = 0.831,P = 0.002),and hepatic blood flow(r = 0.945,P < 0.001;r = 0.930,P < 0.001) as well as a moderate correlation in hepatic perfusion index(r = 0.736,P = 0.01;r = 0.636,P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor.These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumorto-liver CNR during arterial and portal venous phases(5.63 ± 2.38 vs 6.16 ± 2.60,P = 0.814;4.60 ± 1.27 vs 5.11 ± 1.74,P = 0.587).CONCLUSION:Compared with the conventional protocol,low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.

A retrospective analysis of the safety and efficacy of low dose tacrolimus (FK506) for living donor liver transplant recipients

We sought to evaluate the efficacy and effects of low-dose tacrolimus （FK506） to recipients with living donor liver transplantation （LDLT）. A total of 66 patients who underwent LDLT between 2001 and 2007 were enrolled in this study. According to different doses of tacrolimus, the recipients were randomly divided into two groups： the low-dose tacrolimus group （group A） and the normal-dose tacrolimus group （group B）. The blood concentration of tacrolimus and its side effects including infection, hyperglycemia, hypertension, high blood creatinine and jaundice were monitored once a week at the perioperative period, and once a month thereafter. Besides, the survival rates of the recipients were analyzed at the 1and 3-year time point after operation. Among these patients, no significant acute rejection was detected after LDLT. The incidences of infection, hyperglycemia, liver dysfunction and renal impairment in group A were markedly lower than those in group B. However, no significant differences were detected in the incidence of hypertension between the two groups. Moreover, the recipients in each group had a similar survival rate according to the results of 1and 3-year follow-up. The incidence of side effects that associated with tacrolimus positively correlated with tacrolimus blood concentration. In conclusion, long-term and low-dose administration of tacrolimus is a safe and effective treatment for LDLT recipients.

Current status of low dose multi-detector CT in the urinary tract

Over the past several years,advances in the technical domain of computed tomography(CT) have influenced the trend of imaging modalities used in the clinical evaluation of the urinary system.Renal collecting systems can be illustrated more precisely with the advent of multi-detector row CT through thinner slices,high speed acquisitions,and enhanced longitudinal spatial resolution resulting in improved reformatted coronal images.On the other hand,a significant increase in exposure to ionizing radiation,especially in the radiosensitive organs,such as the gonads,is a concern with the increased utilization of urinary tract CT.In this article,we discuss the strategies and techniques availablefor reducing radiation dose for a variety of urinary tractCT protocols with metabolic clinical examples.We also reviewed CT for hematuria evaluation and related scan parameter optimization such as,reducing the number of acquisition phases,CT angiography of renal donors and lowering tube potential,when possible.

Value of low-dose and optimized-length computed tomography(CT)scan in CT-guided percutaneous transthoracic needle biopsy of pulmonary nodules

Objective:To investigate the value of application of low-dose and optimized length CT scan on puncture results,complications and patients’radiation dosage during CT-guided percutaneous biopsy of pulmonary nodules(PTNB).Methods:A total of 231 patients with PTNB under CT guidance were collected.Low dose scanning utilized tube current of 20 mA as compared with 40 mA in conventional dosage.Optimized length in CT is defined as intentionally narrowing the range of CT scanning just to cover 25 mm(5 layers)around the target layer during needle adjustment.According to whether low-dose scans and optimized length scans techniques were utilized,patients were divided into three groups:conventional group(conventional sequence+no optimization),optimized length group(conventional sequence+optimized length),and low-dose optimized length group(low dose sequence+optimized length).The ED(effective dose),the DLP(dose length product),the average CTDIvol(Volume CT dose index),total milliampere second between subgroups were compared.Results:Compared with the conventional group,ED,intraoperative guidance DLP,total milliseconds and operation time in the optimized length group were reduced by 18.2%(P=0.01),37%(P=0.003),17.5%(P=0.013)and13.3%(P=0.021)respectively.Compared with the optimized length group,the ED was reduced by 87%,preoperative positioning,intraoperative guidance and postoperative review DLP were also reduced by 88%,total milliampere second was reduced by 79%,with an average CTDIvol was reduced by 86%,in the low-dose optimized length group(P<0.001 for all).Conclusion:Optimizing the length during CT scanning can effectively reduce the intraoperative radiation dose and reduce the operation time compared with conventional plan;low-dose and optimized length CT scan can further reduce the total radiation dose compared with optimized length group with no differences on intraoperative complications,biopsy results and operation time.

INVOLVEMENT OF THE Ca^(2+) PROTEIN KINASE C AND ADENYLATE CYCLACE SIGNAL PATHWAYS IN THE ACTIVATION OF THYMOCYTES IN RESPONSE TO WHOLE BODY IRRADIATION WITH LOW DOSE X RAYS

WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with different doses of X rays were analyzed for the changes in signal molecules of the phospholipase C phosphatidylinositol biphosphate(PLC IP2) and G protein adenylate cyclase(AC) pathways. [WT5”BX]Results.[WT5”BZ]It was found that[Ca 2+ ] i increased in response to doses within 0 2 Gy which was most marked after 0 075 Gy and the increase was accentuated in the presence of Con A. The changes in CD3 and calcineurin(CN) expression of the thymocytes followed the same pattern as the alterations in [Ca 2+ ] i after LDR. The expression of α,β1 and β2 isoforms of protein kinase C(PKC) was all up regulated after 0 075 Gy with the increase in PKC β1 expression being most marked. The cAMP/cGMP ratio and PKA activity of the thymocytes was lowered after low dose radiation and increased after doses above 0 5 Gy in a dose dependent manner, thus giving rise to J shaped dose response curves. The Ca antagonist TMB 8 and cAMP stimulant cholera toxin suppressed the augmented thymocyte proliferation induced by LDR. [WT5”BX]Conclusion.[WT5”BZ]Data presented in the present paper suggest that activation of the PLC PIP2 signal pathway and suppression of the AC cAMP signal pathway are involved in the stimulation of the thymocytes following WBI with low dose X rays.

Modifications produced by selective inhibitors of cyclooxygenase and ultra low dose aspirin on platelet activity in portal hypertension

AIM: To study the mechanism involved in the potentially beneficial effect of ultra low dose aspirin (ULDA) in prehepatic portal hypertension, rats were pretreated with selective COX 1 or 2 inhibitors (SC-560 or NS-398 respectively), and subsequently injected with ULDA or placebo. METHODS: Portal hypertension was induced by portal vein ligation. Platelet activity was investigated with an in-vivo model of laser induced thrombus production in mesenteric circulation and induced hemorrhagic time (IHT). Platelet aggregation induced by ADP and dosing of prostanoid products 6-keto-PGF1α, TXB2, PGE2 and LTB4 were also performed. RESULTS: The portal hypertensive group receiving a placebo showed a decreased in vivo platelet activity with prolonged IHT, an effect that was normalized by ULDA. SC-560 induced a mild antithrombotic effect in the normal rats, and an unmodified effect of ULDA. NS-398 had a mild prothrombotic action in portal hypertensive rats, similar to ULDA, but inhibited a further effect when ULDA was added. An increased 6-keto-PGF1α was observed in portal hypertensive group that was normalised after ULDA administration. TXA2 level after ULDA, remained unchanged. CONCLUSION: These results suggest that the effect of ULDA on platelet activity in portal hypertensive rats, could act through a COX 2 pathway more than the COX 1, predominant for aspirin at higher doses.

Low Dose Hyper-radiosensitivity in Human Lung Cancer Cell Line A549 and Its Possible Mechanisms

The low dose hyper-radiosensitivity （HRS） in human lung cancer cell line A549 was investigated, the changes of ATM kinase, cell cycle and apoptosis of cells at different doses of radiation were observed, and the possible mechanisms were discussed. A549 cells in logarithmic growth phase were irradiated with ^60Co y-rays at doses of 0-2 Gy. Together with flow cytometry for precise cell sorting, cell survival fraction was measured by means of conventional colony-formation assay. The expression of ATM1981 Ser-P protein was examined by Western blot 1 h after radiation. Apoptosis was detected by Hoechst 33258 fluorescent staining, and Annexin V-FITC/PI staining flow cytometry 24 h after radiation. Cell cycle distribution was observed by flow cytometry 6, 12 and 24 h after radiation. The results showed that the expression of ATM1981Ser-P protein was observed at 0.2 Gy, followed by an increase at 〉0.2 Gy, and reached the peak at 0.5 Gy, with little further increase as the dose exceeded 0.5 Gy. Twenty-four h after radiation, partial cells presented the characteristic morphological changes of apoptosis, and the cell apoptosis curve was coincident with the survival curve. As compared with control group, the cell cycle almost had no changes after exposure to 0.1 and 0.2 Gy radiation （P〉0.05）. After exposure to 0.3, 0.4 and 0.5 Gy radiation, G2/M phase arrest occurred 6 and 12 h after radiation （P〈0.05）, and the ratio of G2/M phase cells was decreased 24 h after radiation （P〈0.05）. It was concluded that A549 cells displayed the phenomenon of HRS/IRR. The mode of cell death was mainly apoptosis. The activity of ATM and cell cycle change may take an important role in HRS/IRR.

High-dose vs low-dose proton pump inhibitors for upper gastrointestinal bleeding:A meta-analysis

AIM:To evaluate the efficacy of high-dose proton pump inhibitors(PPIs)vs low-dose PPIs for patients with upper gastrointestinal bleeding.METHODS:PubMed,Embase,the Cochrane Library,and Web of Science were searched to identify relevant randomized controlled trials(RCTs).Eligible trials were RCTs that compared high-dose PPI with low-dose PPI following endoscopic hemostasis.The primary endpoint was rebleeding;secondary endpoints were patient numbers that needed surgery,and mortality.The meta-analysis was performed with a fixed effects model or random effects model.RESULTS:Nine eligible RCTs including 1342 patients were retrieved.The results showed that high-dose intravenous PPI was not superior to low-dose intra-venous PPI in reducing rebleeding[odds ratio(OR)= 1.091,95%confidential interval(CI):0.777-1.532],need for surgery(OR=1.522,95%CI:0.643-3.605) and mortality(OR=1.022,95%CI:0.476-2.196).Subgroup analysis according to different region revealed no difference in rebleeding rate between Asian patients(OR=0.831,95%CI,0.467-1.480)and European patients(OR=1.263,95%CI:0.827-1.929).CONCLUSION:Low-dose intravenous PPI can achieve the same efficacy as high-dose PPI following endoscopic hemostasis.

Effect of Cycloheximide on the Adaptive Response Induced by Low Dose Radiation

Human lymphocytes pre-exposed to 10 mGy or 50 mGy of X-rays become less sensitive to subsequent large dose irradiation, exhibited lower rate of chromosome aberration than expected. This adaptive response could be inhibited by cycloheximide, a protein synthesis inhibitor for successive 2 h period ranging from 0.5h before to 4h after the low dose exposure, indicating that the adaptive response was directly related with the protein synthesis.