Effects of online cone-beam computed tomography with active breath control in determining planning target volume during accelerated partial breast irradiation

PURPOSE

To test if active breath control during cone-beam computed tomography (CBCT) could improve planning target volume during accelerated partial breast radiotherapy for breast cancer.

METHODS

Patients who were more than 40 years old, underwent breast-conserving dissection and planned for accelerated partial breast irradiation, and with postoperative staging limited to T1-2 N0 M0, or postoperative staging T2 lesion no larger than 3cm with a negative surgical margin greater than 2mm were enrolled. Patients with lobular carcinoma or extensive ductal carcinoma in situ were excluded. CBCT images were obtained pre-correction, post-correction and post-treatment. Set-up errors were recorded at left-right, anterior-posterior and superior-inferior directions. The differences between these CBCT images, as well as calculated radiation doses, were compared between patients with active breath control or free breathing.

RESULTS

Forty patients were enrolled, among them 25 had active breath control. A total of 836 CBCT images were obtained for analysis. CBCT significantly reduced planning target volume. However, active breath control did not show significant benefit in decreasing planning target volume margin and the doses of organ-at-risk when compared to free breathing.

CONCLUSION

CBCT, but not active breath control, could reduce planning target volume during accelerated partial breast irradiation.

Surface Collective Modes in the Topological Insulators Bi_{2}Se_{3} and Bi_{0.5}Sb_{1.5}Te_{3-x}Se_{x}

We used low-energy, momentum-resolved inelastic electron scattering to study surface collective modes of the three-dimensional topological insulators Bi_{2}Se_{3} and Bi_{0.5}Sb_{1.5}Te_{3-x}Se_{x}. Our goal was to identify the "spin plasmon" predicted by Raghu and co-workers [Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary collective mode is a surface plasmon arising from the bulk, free carriers in these materials. This excitation dominates the spectral weight in the bosonic function of the surface χ^{"}(q,ω) at THz energy scales, and is the most likely origin of a quasiparticle dispersion kink observed in previous photoemission experiments. Our study suggests that the spin plasmon may mix with this other surface mode, calling for a more nuanced understanding of optical experiments in which the spin plasmon is reported to play a role.

Investigation of polymorphisms in exon7 of the NSUN7 gene among Chinese Han men with asthenospermia

Previous studies have shown that genetic polymorphisms in exon7 of the NSUN7 gene can be used as an infertility marker in Iranian men with asthenospermia. However, there have been no equivalent studies in China. In the present study, we investigated the possible association between the genetic polymorphisms in exon7 of NSUN7 and asthenospermia in a Chinese Han population. We recruited 240 asthenospermic men as a patient group and 256 normospermic men as a control group, and analyzed the semen parameters on the basis of World Health Organization (WHO) guidelines. The genetic polymorphisms in exon7 of NSUN7 were detected by DNA sequence analysis. The results were analyzed statistically and a P value < 0.05 was considered significant. There were two genetic polymorphisms, c.906C>T and c.922T>G, in exon7 of NSUN7. We found relatively similar genotypes and allele frequencies between the two groups (P = 0.928, P = 0.928, respectively). The combined genotypes of the two polymorphisms did not identify a haplotype associated with asthenospermia (P = 0.824, P = 0.824, respectively). Our findings revealed that genetic polymorphisms in exon7 of the NSUN7 gene are not associated with asthenospermia in Chinese Han men.

Rad51 in regulating the radiosensitivity of non-small cell lung cancer with different epidermal growth factor receptor mutation status

Background

Non‐small cell lung cancer (NSCLC) harboring kinase‐domain mutations in epidermal growth factor receptors (EGFR) has been observed to be sensitive to ionizing radiation (IR). We explore Rad51‐dependent homologous recombination (HR) DNA repair in regulating radiosensitivity in two NSCLC cell lines with different EGFR mutation status.

Methods

NSCLC cell lines, wild‐type EGFR A549 and mutant EGFR H820 with an in‐frame deletion in exon 19 of EGFR (ΔE746–E750), were cultured. Radiosensitivity was estimated by colony forming assay. Rad51 expression was evaluated by quantitative real time‐polymerase chain reaction and Western‐blot. Lentiviral small hairpin ribonucleic acid‐Rad51 and ΔE746–E750 deletion mutant EGFR were constructed and transfected into cells. Flowcytometry assay was used to analyze DNA double strand breaks, cell cycle alterations, and apoptosis.

Results

A549 had a higher survival factor (SF)2 (0.66 vs. 0.44) and lower α/β value (4.07 vs. 9.01). Compared with the A549 cell, the H820 cell exhibited defective arrest in the S‐phase, a higher rate of G2/M accumulation, early apoptosis, and residual γ‐H2AX. Downregulated Rad51 expression decreased SF2 (0.42 vs. 0.31) and increased the α/β ratio (7.51 vs. 10.5), G2/M accumulation, early apoptosis, and γ‐H2AX in two cell lines. H820 had a low IR‐induced Rad51 expression and nuclear translocation. Exogenous expression of the ΔE746–E750 deletion mutant EGFR caused the A549 cell to become more radiosensitive.

Conclusions

An EGFR mutated NSCLC cell line is sensitive to IR, which is correlated with reduced IR‐induced Rad51 expression and nuclear translocation. The signaling pathway of EGFR maintaining Rad51 protein levels maybe a novel lung cancer therapeutic target to overcome radioresistance.

DIGRE: Drug-Induced Genomic Residual Effect Model for Successful Prediction of Multidrug Effects

Multidrug regimens are a promising strategy for improving therapeutic efficacy and reducing side effects, especially for complex disorders such as cancer. However, the use of multidrug therapies is very challenging, due to a lack of understanding of the mechanisms of drug interactions. We herein present a novel computational approach-Drug-Induced Genomic Residual Effect (DIGRE) Computational Model-to predict drug combination effects by explicitly modeling drug response curves and gene expression changes after drug treatments. The prediction performance of DIGRE was evaluated using two datasets: (i) OCI-LY3 B-lymphoma cells treated with 14 different drugs and (ii) MCF breast cancer cells treated with combinations of gefitinib and docetaxel at different doses. In both datasets, the predicted drug combination effects significantly correlated with the experimental results. The results indicated the model was useful in predicting drug combination effects, which may greatly facilitate the discovery of new, effective multidrug therapies.

Whole brain radiotherapy plus simultaneous in-field boost with image guided intensity-modulated radiotherapy for brain metastases of non-small cell lung cancer

Background

Whole brain radiotherapy (WBRT) plus sequential focal radiation boost is a commonly used therapeutic strategy for patients with brain metastases. However, recent reports on WBRT plus simultaneous in-field boost (SIB) also showed promising outcomes. The objective of present study is to retrospectively evaluate the efficacy and toxicities of WBRT plus SIB with image guided intensity-modulated radiotherapy (IG-IMRT) for inoperable brain metastases of NSCLC.

Methods

Twenty-nine NSCLC patients with 87 inoperable brain metastases were included in this retrospective study. All patients received WBRT at a dose of 40 Gy/20 f, and SIB boost with IG-IMRT at a dose of 20 Gy/5 f concurrent with WBRT in the fourth week. Prior to each fraction of IG-IMRT boost, on-line positioning verification and correction were used to ensure that the set-up errors were within 2 mm by cone beam computed tomography in all patients.

Results

The one-year intracranial control rate, local brain failure rate, and distant brain failure rate were 62.9%, 13.8%, and 19.2%, respectively. The two-year intracranial control rate, local brain failure rate, and distant brain failure rate were 42.5%, 30.9%, and 36.4%, respectively. Both median intracranial progression-free survival and median survival were 10 months. Six-month, one-year, and two-year survival rates were 65.5%, 41.4%, and 13.8%, corresponding to 62.1%, 41.4%, and 10.3% of intracranial progression-free survival rates. Patients with Score Index for Radiosurgery in Brain Metastases (SIR) >5, number of intracranial lesions <3, and history of EGFR-TKI treatment had better survival. Three lesions (3.45%) demonstrated radiation necrosis after radiotherapy. Grades 2 and 3 cognitive impairment with grade 2 radiation leukoencephalopathy were observed in 4 (13.8%) and 4 (13.8%) patients. No dosimetric parameters were found to be associated with these late toxicities. Patients received EGFR-TKI treatment had higher incidence of grades 2–3 cognitive impairment with grade 2 leukoencephalopathy.

Conclusions

WBRT plus SIB with IG-IMRT is a tolerable and effective treatment for NSCLC patients with inoperable brain metastases. However, the results of present study need to be examined by the prospective investigations.

An analysis of the small RNA transcriptome of four developmental stages of the citrus red mite (Panonychus citri)

The citrus red mite (Panonychus citri) can feed on more than 112 plant species around the world. Endogenous small RNAs (sRNAs) have proved to be important components of gene regulation in many eukaryotes. Recently, many sRNAs have been shown to be involved in various biological processes, such as development in many animals, including insects; however, to date, no sRNAs have been reported in the citrus red mite. Using Illumina sequencing, several categories of sRNAs were identified, including 594 known microRNAs (miRNAs) grouped into 206 families and 31 novel miRNAs in the four developmental stages of citrus red mite. In addition, according to bioinformatics analysis and S-Poly(T) miRNA assays, the expression level of many miRNAs varied among the developmental stages. Furthermore, the prediction of miRNAs target genes and their functional annotation indicated that miRNAs are involved in the regulation of multiple pathways in the citrus red mite. As the first report of the sRNA world in citrus red mite, the present study furthers our understanding of the roles played by sRNAs in the development of citrus red mite and the data may help to develop methods of controlling the pests in the field.

[Effect of respiratory movement on cone beam computed tomography images]

To investigate the impact of respiratory movement to determine the target volume on cone beam CT (CBCT) for lung tumor, we used CIRS dynamic thorax phantom (Model-CIRS008) to simulate the sinusoidal motion of lung tumor. With a constant amplitude, the ratio of the time of near-end-expiratory and near-end-inspiratory (E/I) changed when it was scanned with CBCT. We analyzed the contrast changes of target by extracting the CT value of each pixel on the center line of the target movement direction. The targets were contoured with region growing method and compared with the motion volume generated by the tumor trajectory method. The result showed that the contrast of near-end-expiratory increased and the contrast of near-end-inspiratory decreased with increasing E/I. The contoured volume generated by region growing method decreased with increasing E/I. When E/I = 4, the amplitude A = 1 cm, diameter of 1 cm and 3 cm target volumes were reduced by 48.2% and 22.7%. The study showed that CBCT was not suitable to be used to accurately determine the range of lung tumor movement. The internal target volume (ITV) may be underestimated in CBCT images.

Implementation of single-breath-hold cone beam CT guided hypofraction radiotherapy for lung cancer

BACKGROUND

To analyze the feasibility of active breath control (ABC), the lung tumor reproducibility and the rationale for single-breath-hold cone beam CT (CBCT)-guided hypofraction radiotherapy.

METHODS

Single-breath-hold CBCT images were acquired using ABC in a cohort of 83 lung cancer patients (95 tumors) treated with hypofraction radiotherapy. For all alignments between the reference CT and CBCT images (including the pre-correction, post-correction and post-treatment CBCT images), the tumor reproducibility was evaluated via online manual alignment of the tumors, and the vertebral bone uncertainties were evaluated via offline manual alignment of the vertebral bones. The difference between the tumor reproducibility and the vertebral bone uncertainty represents the change in the tumor position relative to the vertebral bone. The relative tumor positions along the coronal, sagittal and transverse axes were measured based on the reference CT image. The correlations between the vertebral bone uncertainty, the relative tumor position, the total treatment time and the tumor reproducibility were evaluated using the Pearson correlations.

RESULTS

Pre-correction, the systematic/random errors of tumor reproducibility were 4.5/2.6 (medial-lateral, ML), 5.1/4.8 (cranial-caudal, CC) and 4.0/3.6 mm (anterior-posterior, AP). These errors were significantly decreased to within 3 mm, both post-correction and post-treatment. The corresponding PTV margins were 4.7 (ML), 7.4 (CC) and 5.4 (AP) mm. The changes in the tumor position relative to the vertebral bone displayed systematic/random errors of 2.2/2.0 (ML), 4.1/4.4 (CC) and 3.1/3.3 (AP) mm. The uncertainty of the vertebral bone significantly correlated to the reproducibility of the tumor position (P<0.05), except in the CC direction post-treatment. However, no significant correlation was detected between the relative tumor position, the total treatment time and the tumor reproducibility (P>0.05).

CONCLUSIONS

Using ABC for single-breath-hold CBCT guidance is an effective method to reduce the PTV margin of hypofraction radiotherapy for lung cancer. Using ABC, the tumor position was significantly altered relative to the vertebral position. The reproducibility of the tumor position was affected by the vertebral bone but not by the relative tumor position or the total treatment time.

Correlation between oxidative stress and L-type calcium channel expression in the ventricular myocardia of selenium-deficient mice

OBJECTIVE

Expression of the Cacna1c (calcium channel, voltage-dependent, L-type, α1C subunit) gene was studied to investigate the relationship between oxidative stress and L-type calcium channels in the myocardium of selenium-deficient mice.

METHODS

Selenium levels in liver and heart tissue samples from mice fed normal or selenium-deficient diets were evaluated by fluorometry. In the same mice, glutathione peroxidase (GPx) and Cacna1c gene expression were analysed, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were measured, oxidoreductase gene expression profiles were analysed (by DNA microarray), and myocardial structural changes were studied.

RESULTS

In selenium-deficient versus control mice, GPx expression and SOD activity were decreased, and Cacna1c expression and MDA concentration were increased. Selenoprotein oxidoreductase and nonselenoprotein oxidoreductase gene expression differed significantly between selenium-deficient and control mice. In selenium-deficient mice, myocardial fibres were separated by loose collagenous tissue; electron microscopy showed shortened sarcomeres, dilated sarcoplasmic reticulum, scattered myofibril lysis and increased mitochondria with amorphous matrix densities.

CONCLUSION

L-type calcium channels were involved in selenium deficiency-induced cardiomyocyte injury, which was positively related to oxidative stress.

[Primary study of the threatening of unfixed planning of image guided radiotherapy to the volume margin of neck tumor]

Some patients who have neck tumor but cannot tolerate the thermoplastic immobilization may be supported by simple cushions, and are marked on the neck skin during CT simulation. We therefore set 5 mm as the spinal cord-planning risk volume margin in the intensity-modulated radiotherapy plans in our Centre. Cone beam CT (CBCT) scans were acquired for three times, and matched with the simulation CT images in each radiotherapy. The mean and the standard deviation of the individual, the root mean-square and the standard deviation of the individual were calculated. The matched results of the third CBCT were used to calculate the spinal cord- planning risk volume margin. The results showed that the interfraction error was significantly reduced and the intrafraction error was stable by CBCT guiding. CBCT and 5 mm spinal cord-planning organ is feasible and safe without threatening volume margin to high dose radiotherapy for the patients with neck tumor and not able to tolerate thermoplastic immobilization.