In silico simulation of the effect of hypoxia on MCF-7 cell cycle kinetics under fractionated radiotherapy

The treatment outcome of a given fractionated radiotherapy scheme is affected by oxygen tension and cell cycle kinetics of the tumor population. Numerous experimental studies have supported the variability of radiosensitivity with cell cycle phase. Oxygen modulates the radiosensitivity through hypoxia-inducible factor (HIF) stabilization and oxygen fixation hypothesis (OFH) mechanism. In this study, an existing mathematical model describing cell cycle kinetics was modified to include the oxygen-dependent G1/S transition rate and radiation inactivation rate. The radiation inactivation rate used was derived from the linear-quadratic (LQ) model with dependence on oxygen enhancement ratio (OER), while the oxygen-dependent correction for the G1/S phase transition was obtained from numerically solving the ODE system of cyclin D-HIF dynamics at different oxygen tensions. The corresponding cell cycle phase fractions of aerated MCF-7 tumor population, and the resulting growth curve obtained from numerically solving the developed mathematical model were found to be comparable to experimental data. Two breast radiotherapy fractionation schemes were investigated using the mathematical model. Results show that hypoxia causes the tumor to be more predominated by the tumor subpopulation in the G1 phase and decrease the fractional contribution of the more radioresistant tumor cells in the S phase. However, the advantage provided by hypoxia in terms of cell cycle phase distribution is largely offset by the radioresistance developed through OFH. The delayed proliferation caused by severe hypoxia slightly improves the radiotherapy efficacy compared to that with mild hypoxia for a high overall treatment duration as demonstrated in the 40-Gy fractionation scheme.     

Contribution of Neuropilin-1 in Radiation-Survived Subclones of NSCLC Cell Line H1299

Non-small cell lung cancer (NSCLC) is an aggressive lung cancer accounting for approximately 85% of all lung cancer patients. For the patients with Stages IIIA, IIIB, and IIIC, the 5-year survival is low though with the combination with radiotherapy and chemotherapy. In addition, the occurrence of tumor cells (repopulated tumors) that survive irradiation remains a challenge. In our previous report, we subcloned the radiation-surviving tumor cells (IR cells) using the human NSCLC cell line, H1299, and found that the expression of neuropilin-1 (NRP-1) was upregulated in IR cells by the microarray analysis. Here, we investigated the contribution of neuropilin-1 to changes in the characteristics of IR cells. Although there were no differences in angiogenic activity in the tube formation assay between parental and IR cells, the cell motility was increased in IR cells compared to parental cells in the cell migration assay. This enhanced cell motility was suppressed by pretreatment with anti-NRP-1 antibody. Although further studies are necessary to identify other molecules associated with NRP-1, the increase in cellular motility in IR cells might be due to the contribution of NRP-1. Inhibition of NRP-1 would help control tumor malignancy in radiation-surviving NSCLC.     

The emerging role of miR‐19 in glioma

Glioma has been regarded as the most common, highly proliferative and invasive brain tumour. Advances in research of miRNAs in glioma are toward further understanding of the pathogenesis of glioma. MiR‐19, a member of miR‐17~92 cluster, was reported to play an oncogenic role in tumourigenesis. Here we review the identified data about the effect of miR‐19 on proliferation, apoptosis, migration and invasion of glioma cells, the target genes regulated by miR‐19, and correlation of miR‐19 with the sensitivity of glioma cells to chemotherapy and radiotherapy. It is concluded that miR‐19 plays an important role in the pathogenesis of glioma and can be a potential target for gene therapy of glioma.     

Frequency of whole breast irradiation (WBRT) after intraoperative radiotherapy (IORT) is strongly influenced by institutional protocol qualification criteria

Background

Accelerated partial breast irradiation (APBI) is a promising method of adjuvant radiotherapy for select patients. Intraoperative radiotherapy (IORT) is a form of APBI, and appropriate patient selection is important.

CyberKnife Stereotactic Radiosurgery in brain metastases: A report from Latin America with literature review

Background and aim

Stereotactic radiosurgery is increasingly being employed for the treatment of brain metastases, both as an adjuvant to surgical resection, and also as a primary treatment modality. The aim of this study is to evaluate overall survival and local control in patients with brain metastases treated with CyberKnife Stereotactic Radiosurgery (CKRS), due to the lack of evidence reported in Latin America.

Uncertainty in positioning ion chamber at reference depth for various water phantoms

Background

Uncertainty in the calibration of high-energy radiation sources is dependent on user and equipment type.

Bifunctional Conducting Polymer Coated CoP Core–Shell Nanowires on Carbon Paper as a Free‐Standing Anode for Sodium Ion Batteries

This study proposes a conformal surface coating of conducting polymer for protecting 1D nanostructured electrode material, thereby enabling a free‐standing electrode without binder for sodium ion batteries. Here, polypyrrole (PPy), which is one of the representative conducting polymers, encapsulated cobalt phosphide (CoP) nanowires (NWs) grown on carbon paper (CP), finally realizes 1D core–shell CoP@PPy NWs/CP. The CoP core is connected to the PPy shell via strong chemical bonding, which can maintain a Co–PPy framework during charge/discharge. It also possesses bifunctional features that enhances the charge transfer and buffers the volume expansion. Consequently, 1D core–shell CoP@PPy NWs/CP demonstrates superb electrochemical performance, delivering a high areal capacity of 0.521 mA h cm^?2 at 0.15 mA cm^?2 after 100 cycles, and 0.443 mA h cm^?2 at 1.5 mA cm^?2 even after 1000 cycles. Even at a high current density of 3 mA cm^?2, a significant areal discharge capacity reaching 0.285 mA h cm^?2 is still maintained. The outstanding performance of the CoP@PPy NWs/CP free‐standing anode provides not only a novel insight into the modulated volume expansion of anode materials but also one of the most effective strategies for binder‐free and free‐standing electrodes with decent mechanical endurance for future secondary batteries.     

多西紫杉醇与紫杉醇联合顺铂同步放化疗治疗晚期宫颈癌的疗效比较

目的:比较多西紫杉醇与紫杉醇联合顺铂同步放化疗治疗晚期宫颈癌的疗效。方法:选择2006年6月至2012年6月我院收治的宫颈癌晚期患者180例作为研究对象,依据随机数字表将患者分为紫杉醇组(n=90)和多西紫杉醇组(n=90),两组患者在放疗基础上分别接受紫杉醇135 mg/m~2,每周1次,多西紫杉醇25 mg/m~2,每周1次,4周一疗程,维持两个疗程,比较两组患者的近期疗效、生存时间和毒副作用发生情况。结果:紫杉醇和多西紫杉醇组近期治疗的总有效率分别为81.11%和87.78%,差异无统计学意义(P=0.217);且均未出现进展期的病例。紫杉醇组3年生存率为58.89%,明显低于多西紫杉醇组的75.56%,差异有统计学意义(P=0.017);紫杉醇组骨髓抑制和消化道反应的发生率分别为35.56%和37.78%,明显高于多西紫杉醇组的22.22%和26.67%,差异有统计学意义(均P0.05)。结论:多西紫杉醇联合顺铂同步放化疗治疗晚期宫颈癌能显著提高患者3年生存率,降低毒副作用发生率,且用药量更少,相对安全、合理,患者可耐受,值得进一步临床研究。